Adnexal mass: Differential diagnosis

INTRODUCTION — An adnexal mass (mass of the ovary, fallopian tube, or surrounding connective tissues) is a common gynecologic problem. Adnexal masses may be found in females of all ages, from fetuses to older adults, and there is a wide variety of types of masses (table 1). Pathology in this area may also arise from the uterus, bowel, retroperitoneum, or metastatic disease from another site, such as the gastrointestinal tract or breast.

The different types of adnexal masses are reviewed here. Diagnosis and management of an adnexal mass and other related topics are discussed separately:

●(See "Adnexal mass: Ultrasound categorization".)

●(See "Adnexal mass: Role of serum biomarkers in diagnosing epithelial carcinoma of the ovary, fallopian tube, or peritoneum".)

●(See "Approach to the patient with an adnexal mass".)

●(See "Ovarian cysts in infants, children, and adolescents".)

ANATOMY AND HISTOLOGY

Gross anatomy — The uterine adnexa consist of the ovaries, fallopian tubes, and surrounding vascular, lymphatic, and connective tissues (figure 1).

The ovaries are suspended lateral and/or posterior to the uterus. The supporting structures of the ovaries include the utero-ovarian ligament that attaches the ovary to the uterus; the infundibulopelvic ligament (also referred to as the suspensory ligament of the ovary), through which the ovarian vessels travel, that attaches the ovary to the pelvic sidewall; and the broad ligament, which condenses to form the mesovarium. It is also attached to the broad ligament through the mesovarium.

The ovary consists of an outer cortex, where the ova and follicles are located, and a medulla, where the blood vessels and connective tissue compose a fibromuscular tissue layer (figure 2).

The fallopian tubes arise from the uterine corpus posterior and superior to the round ligaments. The broad ligaments support the tubes with a condensation of connective tissue called the mesosalpinx.

Histology — The ovary includes several different tissue types. The most common neoplasms are epithelial. These derive from the stem cells that would typically give rise to fallopian tube epithelium (most high-grade serous carcinomas), or ovarian surface epithelium and inclusions (eg, cystadenomas). Ovarian germ cell tumors are derived from primordial germ cells of the ovary (figure 3). Ovarian sex cord-stromal tumors derive from stem cells that would normally give rise to supporting epithelial cells, including ovarian stroma (eg, fibromas) and follicles (eg, granulosa cell tumors, Sertoli-Leydig cell tumors).

The fallopian tubes consist of an outer muscularis layer of the tube with longitudinal smooth muscle fibers and an inner layer with circular fibers. The fallopian tube mucosa is composed of numerous delicate papillary folds (plica) consisting of three cell types: ciliated columnar cells; nonciliated, columnar secretory cells; and intercalated cells, which may simply represent inactive secretory cells [1].

Pelvic anatomy and histology is discussed in detail separately. (See "Surgical female pelvic anatomy: Uterus and related structures".)

GYNECOLOGIC TRACT MASSES — There are many different types of adnexal masses (table 1). The likely etiology of an adnexal mass differs by age and reproductive status. This is because some masses are stimulated by reproductive hormones.

In terms of frequency, the distribution of histologic types of adnexal masses in an international cross-section study from the International Ovarian Tumor Analysis (IOTA) group of over 4848 patients is shown in the table (table 2) [2].

Fetuses, children, and adolescents — Follicular ovarian cysts are common in fetuses and increase in frequency with advancing gestational age and with some maternal complications (eg, diabetes mellitus, preeclampsia, Rh isoimmunization).

A pelvic mass in a newborn is most likely a physiologic cyst that initially arose due to maternal hormonal stimulation in utero. The differential diagnosis of an intra-abdominal mass in fetuses or neonates includes genitourinary tract disorders (eg, reproductive tract anomalies, urinary tract obstruction, urachal cyst), gastrointestinal tract disorders (eg, mesenteric or omental cyst, volvulus, colonic atresia, intestinal duplication), or miscellaneous disorders (eg, choledochal, splenic, or pancreatic cyst, lymphangioma).

Between the neonatal period and puberty, physiologic cysts are uncommon because gonadotropin ovarian stimulation decreases in infancy and early childhood and then increases during puberty. Nevertheless, most simple ovarian cysts in children are physiologic and result from enlargement of a cystic follicle.

Between menarche and age 18, ovulatory dysfunction is common due to an immature hypothalamic-pituitary-ovarian axis. Adolescent ovaries may contain multiple follicles in different stages of development and include unilocular cysts (resulting from failure of the maturing follicle to ovulate and involute) and hemorrhagic cysts. These dysfunctional follicles typically resolve spontaneously and are often clinically insignificant.

Ovarian neoplasms (benign and malignant) account for approximately 1 percent of all tumors in children and adolescents. Most ovarian masses are physiologic or benign neoplasms; fewer than 5 percent of ovarian cancers occur in this age group.

Ovarian cancer is the most common gynecologic malignancy in patients ≤25 years of age, and germ cell tumors are the most common histology [3]. Germ cell tumors compose one-half to two-thirds of ovarian neoplasms in patients up to 18 years of age compared with 20 percent of ovarian neoplasms in adult patients. In patients younger than nine years of age, approximately 80 percent of ovarian neoplasms are malignant. Epithelial neoplasms are rare in the prepubertal age group.

The etiology, diagnosis, and management of ovarian neoplasms from the fetal to adolescent age group are reviewed separately. (See "Ovarian cysts in infants, children, and adolescents".)

Premenopausal patients — There is a broad differential diagnosis of an adnexal mass in patients of reproductive age. Adnexal masses stimulated by reproductive hormones are found almost exclusively in this age group. These include physiologic cysts, endometriomas, and leiomyomas. Ovarian or tubal malignant neoplasms are uncommon in this age group, although the peak age for ovarian germ cell tumors is between ages 10 and 30 years.

Adnexal masses in the reproductive-age patients that are associated with reproductive hormones include some that result from an aspect of the menstrual cycle, including:

●Functional/physiologic cysts

●Corpus luteal cyst

●Theca lutein cyst

Other types of masses are stimulated by reproductive hormones:

●Endometrioma

●Uterine leiomyoma

Premenopausal patients may develop benign or malignant neoplastic adnexal masses. These occur most commonly in the ovary but may develop in the fallopian tube.

Common benign neoplasms include mature teratomas and cystadenomas. In general, ovarian or tubal cancers increase in incidence with increasing age and so are more common in postmenopausal patients. However, ovarian germ cell tumors (eg, teratomas) arise primarily in young patients between 10 and 30 years of age; they represent 70 percent of ovarian neoplasms in this age group [4].

Ovulatory — Some adnexal masses are associated with normal or abnormal ovulatory function.

Functional or corpus luteal cysts — In the process of normal ovulation, a follicle develops to maturity and then ruptures to release an ovum; this is followed by formation and subsequent involution of the corpus luteum (figure 4). (See "Normal menstrual cycle".)

Follicular cysts (also referred to as physiologic cysts) arise when rupture does not occur and the follicle continues to grow; corpus luteal cysts occur when the corpus luteum fails to involute and continues to enlarge after ovulation (the corpus luteum enlarges for the first six weeks of pregnancy and doubles its prepregnancy size [5]). These cysts are therefore called physiologic or functional. Either type may become hemorrhagic.

Follicular cysts appear smooth, thin walled, and unilocular on ultrasound examination (image 1), while corpus luteum cysts can look complex and grossly are yellow (image 2). Unilocular cysts <3 cm in diameter are considered to be normal follicles. Physiologic or follicular cysts can become quite large but are usually less than 10 cm in size. The Society of Radiologists in Ultrasound (RSU) Consensus Conference Statement has developed guidelines to address which cysts need to be followed and which can be ignored, this is discussed in detail separately [6]. (See "Adnexal mass: Ultrasound categorization", section on 'Step one: Is it a simple cyst?'.)

Corpus luteal cysts in the normal menstrual cycle may have a variety of appearances on ultrasound. They are unilocular and can contain internal debris (hemorrhage) and thick walls. They can also be enlarged, up to 8 cm, but typically resolve spontaneously [7].

An early intrauterine pregnancy is always associated with a corpus luteum, which is typically <2.5 cm in diameter. However, the corpus luteum may occasionally become enlarged and painful due to hemorrhage.

Functional and corpus luteal cysts are generally asymptomatic unless they rupture, they become hemorrhagic, or torsion occurs. Most spontaneously resolve within a few weeks, but some persist for several months. (See "Evaluation and management of ruptured ovarian cyst" and "Ovarian and fallopian tube torsion".)

Theca lutein cysts — Theca lutein cysts (also called lutein cysts or hyperreactio luteinalis) are luteinized follicle cysts that form as a result of overstimulation from high human chorionic gonadotropin (hCG) levels or extreme sensitivity to hCG.

Bilateral multiseptated cystic adnexal masses in a patient with gestational trophoblastic disease, multiple gestation, ovarian hyperstimulation, or a pregnancy complicated by fetal hydrops are likely to be theca lutein cysts rather than malignant neoplasms. This type of cyst can also occur in a normal pregnancy due to hypersensitivity to normal levels of hCG. (See "Adnexal mass: Evaluation and management in pregnancy", section on 'Types of adnexal masses in pregnant patients' and "Hydatidiform mole: Epidemiology, clinical features, and diagnosis", section on 'Ovarian theca lutein cysts'.)

Most theca lutein cysts are asymptomatic, but maternal virilization, hyperemesis gravidarum, preeclampsia, or thyroid dysfunction may occur. The cysts gradually resolve weeks to months after the source of hCG is eliminated. (See "Gestational hyperandrogenism".)

Polycystic ovaries — Polycystic ovary syndrome (PCOS) results in enlarged ovaries with multiple small peripheral follicles in some patients (image 3). Although the ovaries are enlarged, patients with PCOS rarely present with an adnexal mass.

The classic phenotype of PCOS is a patient who is obese, hirsute, and anovulatory. Polycystic ovarian morphology visualized on ultrasound includes an antral follicle count >20 and/or increased ovarian volume (>10 mL, calculated using the formula 0.5 x length x width x thickness) in at least one of the ovaries. Typically, multiple small follicles (2 to 9 mm) at the periphery of the ovary and increased central stroma are also seen. (See "Clinical manifestations of polycystic ovary syndrome in adults", section on 'Ultrasound appearance'.)

PCOS is treated to manage abnormal uterine bleeding, infertility, insulin resistance, obesity, and hirsutism. The polycystic ovaries themselves do not require treatment. (See "Treatment of polycystic ovary syndrome in adults".)

Pregnancy-related — Some types of adnexal mass are found only in pregnant patients.

Corpus luteum of pregnancy — An early intrauterine pregnancy is always associated with a corpus luteum cyst and is discussed in detail separately. (See 'Functional or corpus luteal cysts' above and "Adnexal mass: Evaluation and management in pregnancy", section on 'Benign neoplasms' and "Adnexal mass: Evaluation and management in pregnancy", section on 'Management of corpus luteum'.)

Luteoma — Luteoma is a non-neoplastic ovarian mass associated with pregnancy; it is essentially a corpus luteum that is solid rather than cystic. A luteoma is sometimes mistaken for a neoplasm on clinical, gross, or microscopic examination [8]. Luteomas involute spontaneously after delivery. The diagnosis should be suspected in the presence of a solid adnexal mass and maternal hirsutism or virilization. (See "Gestational hyperandrogenism".)

Decidualization of endometrioma — Endometriomas may become decidualized during pregnancy. This can raise suspicion of a malignant mass due to the presence of a solid element with flow. These changes resolve after pregnancy. (See 'Endometrioma' below.)

Ectopic pregnancy — An ectopic pregnancy may present as an adnexal mass noted on pelvic examination or ultrasound. Signs and symptoms suggestive of ectopic pregnancy include a history of a missed menstrual period, abdominopelvic pain, and vaginal bleeding. An ectopic pregnancy is potentially life-threatening, and any patient with a possible ectopic pregnancy should be evaluated immediately. (See "Ectopic pregnancy: Clinical manifestations and diagnosis" and "Ultrasonography of pregnancy of unknown location".)

Stimulated by reproductive hormones — Adnexal masses that are stimulated by reproductive hormones tend to regress and become asymptomatic after menopause.

Endometrioma — An endometrioma is a benign cause of an adnexal mass arising from the ectopic growth of endometrial tissue.

Patients with endometriosis often complain of pelvic pain, dysmenorrhea, and dyspareunia. An endometrioma, or "chocolate cyst," appears as a unilocular or multilocular cystic mass on ultrasound, typically containing homogeneous internal echoes. The ultrasound appearance of an endometrioma is often described as containing "ground glass" internal echoes (image 4). The chocolate-colored fluid, or old blood contained in the cyst, has a classic appearance. (See "Endometriosis in adults: Pathogenesis, epidemiology, and clinical impact" and "Endometriosis: Management of ovarian endometriomas".)

Leiomyoma — A leiomyoma (fibroid) is a benign neoplasm of smooth muscle origin, which usually arises from the uterus but may also be found in the broad ligament (picture 1).

Most patients with symptomatic fibroids are in their 30s or 40s. Myomas are clinically apparent in approximately 25 percent of reproductive-age patients and noted on pathologic examination in approximately 80 percent of surgically excised uteri. (See "Uterine fibroids (leiomyomas): Epidemiology, clinical features, diagnosis, and natural history".)

Depending on the size and location of the leiomyoma, patients often present with complaints of pelvic pressure, pain, heavy menstrual bleeding, and/or dysmenorrhea. Physical examination usually reveals an enlarged, irregularly shaped uterus that appears as a solid uterine tumor or tumors on ultrasound examination.

A fibroid arising from the posterior uterus and projecting into the posterior cul-de-sac (pouch of Douglas) or coming from the fundus as a pedunculated mass can be confused with an ovarian neoplasm (picture 1). Cystic degeneration of a fibroid can result in the appearance of a fluid-filled center of the fibroid on ultrasound. This, coupled with the fact that fibroids can cause an elevation in the serum cancer antigen 125 (CA 125) concentration, results in further concern that the mass may be a malignant ovarian neoplasm. Transvaginal imaging is key to differentiating between a leiomyoma in the adnexa from a solid ovarian tumor. First, the ovary must be found intact, normal, and completely separate from the leiomyoma. Also, Doppler flow can be used to see the vascular communication between the uterus and the pedunculated leiomyoma.

Infectious or inflammatory

Tubo-ovarian abscess — A tubo-ovarian abscess (TOA) is an inflammatory mass involving the fallopian tube, ovary, and, occasionally, other adjacent pelvic organs (eg, bowel, bladder). This may manifest as a tubo-ovarian complex (an agglutination of those structures) or a collection of pus (TOA). These abscesses are found most commonly in reproductive-age patients and typically result from upper genital tract infection. TOA is usually a complication of pelvic inflammatory disease (PID).

Findings of abdominopelvic pain, fever, purulent cervical discharge, and cervical motion tenderness in association with an adnexal mass suggest a diagnosis of TOA. (See "Epidemiology, clinical manifestations, and diagnosis of tubo-ovarian abscess".)

Hydrosalpinx — Untreated or undertreated cases of PID result in scarring or "clubbing" of the tubal fimbriae. This leads to a collection of either tubal secretions or pus, resulting in a hydrosalpinx or pyosalpinx, respectively.

After acute infection has resolved, a hydrosalpinx may remain. The tubal function is often compromised, and this may contribute to infertility. (See "Pelvic inflammatory disease: Long-term complications", section on 'Hydrosalpinx'.)

A hydrosalpinx should be suspected when a dilated, tubular cystic structure is seen adjacent to the ovary. Hydrosalpinges often have incomplete septations. Three-dimensional ultrasound using sectional planes is useful to visually reconstruct the hydrosalpinx (image 5). Luminal contents vary from serous (hydrosalpinx) to blood (hematosalpinx) or pus (pyosalpinx).

Benign neoplasms — Ovarian/tubal neoplasms may arise from stem cells, which typically give rise to the surface epithelium, fallopian tube epithelium, germ cells, or sex cord-stromal cells (figure 3 and image 6). The most common types of benign neoplasms in reproductive-age patients are mature cystic teratoma (dermoid cyst) followed by serous cystadenoma and then mucinous cystadenoma [2,9]. Mature cystic teratomas are a type of germ cell tumor; these ovarian neoplasms are found most commonly in patients ages 10 to 30 years [10].

Serous or mucinous cystadenoma — Serous and mucinous cystadenomas are among the most common benign ovarian neoplasms. They are thin walled, uni- or multilocular, and range in size from 5 to <20 cm.

Compared with serous cystadenomas, mucinous cystadenomas occur less frequently, are more likely to be multiloculated, are larger (they can attain an enormous size), and are less often bilateral (less than 5 versus 20 to 25 percent) (table 3). A definitive diagnosis depends on pathologic evaluation to determine the cell type lining the cysts. Serous lining is similar to fallopian tube lining, and mucinous lining cells collect mucin in their cytoplasm and resemble either endocervical or gastrointestinal epithelium.

Many of these tumors are asymptomatic and found incidentally on pelvic examination or with ultrasound. As the masses grow, they can cause pressure or pain, bloating, and urinary symptoms and can present with ovarian torsion.

The management of these masses is discussed in detail elsewhere. (See "Approach to the patient with an adnexal mass", section on 'Management'.)

Mature cystic teratoma — A mature cystic teratoma (dermoid cyst) is a benign germ cell tumor and is the most common ovarian neoplasm in the second and third decades of life [10]. Mature teratomas can contain elements differentiated to all three germ cell layers: ectodermal (eg, skin, hair follicles, sebaceous glands), mesodermal (eg, muscle, urinary), and endodermal origin (eg, lung, gastrointestinal).

Transvaginal ultrasound usually reveals a unilocular cystic mass, which can contain hyperechoic contents, hyperechoic lines or dots, fluid, and areas of acoustic shadowing. Mature teratomas may have a variety of appearances depending on their content (image 7 and image 8). The tumors are bilateral in 10 to 15 percent of patients (table 3) [11]. (See "Ovarian germ cell tumors: Pathology, epidemiology, clinical manifestations, and diagnosis", section on 'Mature teratoma (dermoid)'.)

Endosalpingiosis — Endosalpingiosis is the presence of non-neoplastic, ectopic, cystic glands outside the fallopian tube that are lined with fallopian tube-type ciliated epithelium [12]. Endosalpingiosis may occur in pelvic organs, including ovaries, fallopian tube serosa, uterine serosa, myometrium, or pelvic peritoneum. It may also occur in the bladder or in a retroperitoneal or axillary lymph node [13]. Endosalpingiosis is not well studied, and the clinical features remain uncertain. Similar müllerian inclusions occur less frequently and may be lined by mucinous or endometrioid epithelium.

Rarely, endosalpingiosis presents as large, tumor-like cystic masses involving the uterine serosa (figure 5) or bladder epithelium (picture 2) [14,15]. (See "Endosalpingiosis".)

Paraovarian/paratubal cysts and tubal and broad ligament neoplasms — Neoplasms arising from the fallopian tube or broad ligament (figure 6 and picture 3A-B) are rare, although it is now believed that most high-grade serous carcinomas in the adnexa arise in the fallopian tubes. Since the tubes and broad ligaments are not usually visualized on ultrasound examination, the source of these tumors may be erroneously attributed to the ovary or uterus, which are more common sites for neoplasms.

The most common findings in this area are unilocular, anechoic, simple cysts that originate from the remnants of paramesonephric (müllerian) or mesonephric (Wolffian) ducts that are present during urogenital embryologic development (picture 3A) [16,17]. These are not neoplastic. The histology of these lesions may also be mesothelial. Paramesonephric cysts are most common, in particular the hydatid cyst of Morgagni [18,19]. A hydatid cyst of Morgagni is attached to the tubal fimbriae and contains serous fluid surrounded by a translucent wall. These are non-neoplastic cysts lined by either mesothelium or fallopian tube-like epithelium.

Neoplasms may also present as paratubal or paraovarian masses. In a retrospective study of 59 patients who underwent surgery for cystic paraovarian lesions, 75 percent had simple cysts and 25 percent had neoplastic lesions (seven cystadenomas and eight cystadenofibromas); there were no malignant neoplasms [20]. A primary malignancy deriving from the paratubal or paraovarian lesions is rare; a literature review found 14 reports of malignant or borderline paraovarian epithelial neoplasms [21]; however, metastatic malignancies often involve the paraovarian or paratubal tissues.

These cysts are usually discovered incidentally during pelvic sonography or surgery. There are no data regarding whether these cysts, either benign or malignant, are more common in pre- or postmenopausal patients. The key to diagnosis is a unilocular, anechoic cyst seen adjacent to a normal ovary.

When a paratubal or paraovarian cyst is symptomatic, it most commonly presents as dull unilateral pelvic pain [17]. As with larger ovarian cysts, a paratubal cyst may result in torsion of the adnexa and acute severe pain requiring emergency surgical intervention (picture 3B) (see "Ovarian and fallopian tube torsion"). A simple, asymptomatic paratubal or paraovarian cyst can be managed expectantly. (See "Approach to the patient with an adnexal mass", section on 'Management according to mass type'.)

It is often difficult to distinguish between a paratubal cyst and an exophytic simple ovarian cyst as they can look similar on ultrasound. It is not clinically relevant to distinguish them as both are benign cysts and can be managed similarly.

Rarely, a leiomyoma may arise in the fallopian tube or broad ligament. An adenomatoid "tumor" may arise in the fallopian tube. It is unclear whether such a tumor is neoplastic. It is a benign mesothelial proliferation that grossly resembles a leiomyoma and histologically may be confused with a carcinoma [22].

Malignant neoplasms — The incidence of ovarian malignant neoplasms in patients of this age group with an adnexal mass ranges from 6 to 11 percent [23]. Most primary ovarian neoplasms are partially cystic and derive from epithelial cells, although they can also arise from other cell types, such as germ cell, sex cord-stromal, and mixed cell types. Germ cell tumors are the second most common type of ovarian neoplasm in females younger than 30 years old, but they become rare after this age. (See "Epithelial carcinoma of the ovary, fallopian tube, and peritoneum: Clinical features and diagnosis" and "Ovarian germ cell tumors: Pathology, epidemiology, clinical manifestations, and diagnosis" and "Sex cord-stromal tumors of the ovary: Epidemiology, clinical features, and diagnosis in adults" and "Ovarian cysts in infants, children, and adolescents".)

The ovary can also be involved by metastatic malignant neoplasms forming in the gynecologic tract or nongynecologic primary sites ("Krukenberg tumor"), especially from endometrial carcinoma or gastrointestinal tract or breast cancer. (See 'Metastatic disease' below.)

Postmenopausal patients — Most adnexal cysts in postmenopausal patients are benign, but the incidence of ovarian cancer increases with advancing age; at least 30 percent of ovarian masses in patients over age 50 are malignant neoplasms [23]. Malignant adnexal masses include those of primary ovarian or tubal origin or metastatic lesions from other primary malignant neoplasms (eg, endometrial, breast, or gastrointestinal tract).

Nonmalignant etiologies of an adnexal mass in postmenopausal patients include many of those also seen in patients of reproductive age, such as cystadenoma, paraovarian cyst, or hydrosalpinx. Leiomyomas or endometriomas are stimulated by estrogen, serum levels of which decrease significantly after menopause. Thus, these lesions typically decrease in size in postmenopausal patients but may remain as smaller masses.

Simple cysts are common in this age group. They most commonly represent either persistent physiologic/functional cysts from the premenopausal period, benign cystadenomas, or paraovarian or paratubal cysts/hydrosalpinx [24-26].

Neoplastic

Epithelial neoplasms — Benign or borderline ovarian epithelial neoplasms may also occur in postmenopausal patients. These include serous or mucinous cystadenomas or serous, mucinous, or endometrioid borderline neoplasms. (See 'Serous or mucinous cystadenoma' above and "Epithelial carcinoma of the ovary, fallopian tube, and peritoneum: Histopathology", section on 'Overview of borderline neoplasms'.)

Epithelial carcinoma is the most common histologic type of cancer of the ovary, fallopian tube, and peritoneum, accounting for 90 percent of all cancers at these sites [27,28]. Ovarian carcinoma is traditionally referred to as a single entity, but it consists of a heterogeneous group of neoplasms with multiple histologic subtypes [29].

Based on histopathology, immunohistochemistry, and molecular genetic analysis, the five main subtypes of epithelial ovarian, fallopian tube, and peritoneal carcinomas and their relative proportions are [29]:

●High-grade serous carcinoma (HGSC; 70 to 80 percent)

●Endometrioid carcinoma (10 percent)

●Clear cell carcinomas (10 percent)

●Mucinous carcinoma (3 percent)

●Low-grade serous carcinoma (LGSC; <5 percent)

The different subtypes also differ in risk factors and clinical behavior. It has been proposed that what had been diagnosed as ovarian or peritoneal serous carcinomas (HGSC and LGSC) may originate from fallopian tube precursors, serous tubal intraepithelial neoplasia/carcinoma in the case of HGSC, and endosalpingiosis/müllerian rests in the case of LGSC [30-37]. The histopathology, risk factors, and diagnosis of serous ovarian, fallopian tube, and peritoneal carcinomas are discussed separately. (See "Epithelial carcinoma of the ovary, fallopian tube, and peritoneum: Histopathology" and "Epithelial carcinoma of the ovary, fallopian tube, and peritoneum: Incidence and risk factors".)

High-grade tubal intraepithelial neoplasia/carcinoma is typically seen either associated with an ovarian or tubal mass or as a pathology result after risk-reducing salpingo-oophorectomy in a patient with a BRCA mutation. These are microscopic lesions and do not present as a mass.

The average age at diagnosis of ovarian, tubal, or peritoneal carcinoma is approximately 60-years old. Patients often present with vague gastrointestinal symptoms including dyspepsia, early satiety, anorexia, constipation, and bloating; these nonspecific complaints are associated with advanced disease. Physical findings may include an adnexal or abdominopelvic mass, abdominal distention with ascites, and/or pleural effusion. (See "Epithelial carcinoma of the ovary, fallopian tube, and peritoneum: Clinical features and diagnosis", section on 'Clinical presentation'.)

Pelvic ultrasound findings in patients with epithelial ovarian cancer usually include an adnexal mass with findings suspicious for malignancy (eg, large solid component, irregular papillary projections, increased blood flow), either unilateral or bilateral, often accompanied by ascites (image 9) [38]. (See "Adnexal mass: Ultrasound categorization".)

Germ cell tumors — Ovarian germ cell tumors are derived from primordial germ cells of the ovary (figure 3). They may be benign or malignant. In our experience, the most common germ cell tumor in postmenopausal patients is malignant degeneration of a teratoma. These neoplasms comprise approximately 20 to 25 percent of ovarian neoplasms overall but account for only approximately 5 percent of all malignant ovarian neoplasms [39-41]. Ovarian germ cell tumors arise primarily in young patients between 10 and 30 years of age and represent 70 percent of ovarian neoplasms in this age group [4]. Mature teratomas are sometimes seen in postmenopausal patients, but malignant germ cell tumors are exceedingly rare in the postmenopausal age group. (See "Ovarian germ cell tumors: Pathology, epidemiology, clinical manifestations, and diagnosis".)

Sex cord-stromal tumors — Ovarian sex cord-stromal tumors are a heterogeneous group of benign or malignant neoplasms that develop from the dividing cell population that would normally give rise to cells surrounding the oocytes (the nongerm cell and nonepithelial components of the gonads) (figure 3) [42]. These neoplasms are rare, comprising only 1.2 percent of all primary ovarian cancers (malignant neoplasms) [43]. The average age at diagnosis is approximately 50 years.

The histologic types of sex cord-stromal tumors include granulosa-stromal cell (eg, granulosa cell tumor, fibroma, thecoma), Sertoli-stromal (eg, Sertoli-Leydig cell tumor), and granulosa and Sertoli-Leydig elements (eg, gynandroblastoma).

Sex cord-stromal tumors are often comprised of cells that produce ovarian hormones, including estrogen and androgens. These may result in symptoms of estrogen excess or other effects, and measurement of these and other tumor markers may play a role in diagnosis (table 4). They rarely may be associated with Meigs syndrome. Meigs syndrome includes findings of an adnexal mass, ascites, and pleural effusions [44].

Ovarian sex cord-stromal tumors are discussed in detail separately. (See "Sex cord-stromal tumors of the ovary: Epidemiology, clinical features, and diagnosis in adults".)

Simple ovarian cysts — Simple, unilocular, anechoic ovarian cysts are common in postmenopausal patients.

Simple cysts that develop during menopause probably represent either persistent physiologic/functional cysts from the premenopausal period, nonovulatory ovarian activity, benign cystadenomas, paratubal cysts, or hydrosalpinges [24-26]. High levels of gonadotropins or androgens may cause small, epithelial-lined structures in the ovary to secrete fluid into their inner cavity and enlarge to become cysts. This is not uncommon, especially in the first few years after menopause [24-26,45].

The prevalence of a simple unilocular cyst in postmenopausal patients ranges from 2.5 to 18 percent, depending on the population and criteria used (eg, <5 or <10 cm) [45,46]. The risk of ovarian cancer in a patient with a simple cyst on a high-quality sonogram is low and discussed in detail separately. (See "Approach to the patient with an adnexal mass", section on 'Management according to mass type'.)

Other gynecologic etiologies — Leiomyomata may persist into the menopausal years, but new myomas typically do not develop. Similarly, endometriomas that developed prior to menopause may remain on/in the ovary. Previous imaging should be reviewed to determine whether an adnexal mass is a new mass that developed after menopause. (See 'Leiomyoma' above and 'Endometrioma' above and "Uterine fibroids (leiomyomas): Epidemiology, clinical features, diagnosis, and natural history", section on 'Postmenopausal patients' and "Endometriosis: Management of ovarian endometriomas".)

NONGYNECOLOGIC MASSES

Metastatic disease — The ovaries and fallopian tubes are common sites of metastases of endometrial, breast, and some gastrointestinal malignant neoplasms. In studies of 50 or more cases of metastatic neoplasms to the ovary, the sites of primary tumors included colon cancer (15 to 32 percent), breast (8 to 28 percent), gastric (6 to 22 percent), and appendix (2 to 20 percent) [47-49]. Rarely, lymphoma or sarcomas may metastasize to the ovary and present as ovarian masses. (See "Epithelial carcinoma of the ovary, fallopian tube, and peritoneum: Clinical features and diagnosis", section on 'Surveilling for other cancers'.)

Abdominopelvic abscess — Infectious or inflammatory causes of an adnexal mass that are not derived from the gynecologic tract include lesions of the gastrointestinal tract (especially diverticulitis and, less often, appendicitis) or any other type of pelvic abscess. (See "Posthysterectomy pelvic abscess" and "Clinical manifestations and diagnosis of acute colonic diverticulitis in adults" and "Acute appendicitis in adults: Clinical manifestations and differential diagnosis".)

The prevalence of diverticular disease in the general population is age dependent, increasing from less than 5 percent at age 40, to 30 percent by age 60, and 65 percent by age 85. During an episode of diverticulitis, a tender mass is palpable in approximately 20 percent, and abdominal distention is common. Symptoms include fever, abdominal pain (usually left lower quadrant), nausea and vomiting, constipation, diarrhea, and urinary symptoms. Diverticular disease should be considered in the older patient who presents with fever, left-sided pelvic pain, and a pelvic mass on pelvic or ultrasound examination.

In a patient with constipation, a somewhat firm, usually mobile adnexal mass may be palpated on pelvic examination. However, this resolves if the constipation is treated.

Examples of other bowel masses that may present as an adnexal mass include: appendiceal tumor or inflammatory mass, a tumor arising from a Meckel's diverticulum, and gastrointestinal stromal tumors of the small and large intestine.

Urinary tract masses — Urinary tract masses that may present as an adnexal mass on pelvic examination or imaging include bladder diverticulum, ureteral diverticulum, and pelvic kidney. (See "Renal ectopic and fusion anomalies".)

Other masses — Other types of abdominopelvic masses that may present as an adnexal mass on pelvic examination or imaging include peritoneal and omental cysts, intraligamentous masses, and various retroperitoneal lesions.

A peritoneal inclusion cyst may occur as a result of pelvic adhesions. The typical presentation is a patient with prior surgery (especially hysterectomy) or history of inflammation (pelvic inflammatory disease) with a cystic mass seen on transvaginal ultrasound that is not clearly palpable. The ultrasound appearance includes pockets of fluid in the pelvis separated by filmy adhesions that can move ("flapping sails" sign). Often the ovary, if present, is contained within the loculated fluid, which conforms to surrounding pelvic structures and sidewalls. There is generally an irregular-shaped exterior border rather than a round cyst [6]. Resolution of the loculated fluid or reduction of the volume may be seen over time as this is peritoneal fluid trapped within filmy adhesions. (See "Adnexal mass: Ultrasound categorization", section on 'Peritoneal inclusion cyst'.)

Malignant peritoneal mesothelioma is a rare neoplasm of the serosal membranes of the pleura, peritoneum, pericardium, or tunica vaginalis testes. The disease distribution is typically diffuse, but localized disease may occur and could potentially be detected as an adnexal mass. There are no signs or symptoms that are specific for malignant peritoneal mesothelioma. The most frequent symptoms are abdominal distention/pain, weight loss, dyspnea, and chest pain. (See "Malignant peritoneal mesothelioma: Epidemiology, risk factors, clinical presentation, diagnosis, and staging".)

ADNEXAL MASS COMPLICATIONS — In addition to the presence of an adnexal mass, complications may occur that have characteristic symptoms, patterns, or findings on pelvic imaging.

Hemorrhagic ovarian cyst — An ovarian cyst may become hemorrhagic (ie, there may be bleeding within the cyst). Patients with a hemorrhagic cyst may be asymptomatic or may present with mild to severe pelvic pain. Ultrasound features typically include a cystic mass with internal echoes, which vary depending on the evolution of a blood clot. There may be a fluid level if there has been fresh bleeding or a blood clot that appears as an avascular solid internal mass. Or there can be "cobweb" internal echoes as the blood clot resolves. Hemorrhagic cysts or hemorrhagic corpus luteum cysts usually occur with ovulatory dysfunction. Patients who are on anticoagulation are at increased risk. (See "Adnexal mass: Ultrasound categorization", section on 'Step two: Are findings consistent with another physiologic process?' and "Evaluation and management of ruptured ovarian cyst".)

Ruptured ovarian cyst — An ovarian cyst may rupture. This is typically accompanied by the sudden onset of moderate to severe pelvic pain. Ruptured ovarian cysts may cause bleeding. Most may be managed expectantly, but surgical management is required in some cases. (See "Evaluation and management of ruptured ovarian cyst".)

Adnexal torsion — Ovarian torsion refers to the complete or partial rotation of the ovary on its ligamentous supports, often resulting in ischemia. The fallopian tube often twists along with the ovary; when this occurs, it is referred to as adnexal torsion. The primary risk factor for ovarian torsion is an ovarian mass and is most common if the ovary is 5 cm or larger.

Pelvic ultrasound is the first-line imaging study for patients with suspected ovarian torsion and will identify a mass or cyst that is usually 5 to 10 cm. Power Doppler can be used to evaluate blood flow to the ovary, but the diagnosis and decision for surgery is a clinical one. Blood flow will be seen unless the torsion involves complete obstruction of the supplying vessels, so observing blood flow to the ovary does not rule out adnexal torsion. The "whirlpool sign" represents the twisted vascular pedicle as seen with color Doppler. A definitive diagnosis of ovarian torsion is made by direct visualization of a rotated ovary at the time of surgical evaluation. (See "Ovarian and fallopian tube torsion".)

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Ovarian and fallopian tube disease".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topic (see "Patient education: Ovarian cysts (The Basics)")

●Beyond the Basics topic (see "Patient education: Ovarian cysts (Beyond the Basics)")

SUMMARY AND RECOMMENDATIONS

●Clinical significance – An adnexal mass (mass of the ovary, fallopian tube, or surrounding connective tissues) is a common gynecologic problem and may be found in females of all ages. While there are many different types of adnexal masses (table 1), the likely etiology differs by age and reproductive status. (See 'Introduction' above.)

●Histology – Ovarian neoplasms derive from the three different ovarian cell types. The most common ovarian neoplasms are epithelial. These derive from the stem cells that would typically give rise to fallopian tube epithelium (most high-grade serous carcinomas), or ovarian surface epithelium and inclusions (eg, cystadenomas). Ovarian germ cell tumors are derived from primordial germ cells of the ovary (figure 3). Ovarian sex cord-stromal tumors derive from stem cells that would normally give rise to supporting epithelial cells, including ovarian stroma (eg, fibromas) and follicles (eg, granulosa cell tumors, Sertoli-Leydig cell tumors). (See 'Histology' above.)

●Gynecologic tract masses

•Fetus, children, and adolescents – Ovarian neoplasms (benign and malignant) account for approximately 1 percent of all tumors in children and adolescents. In this age group, most ovarian masses are physiologic or benign neoplasms; fewer than 5 percent of ovarian masses in such patients are ovarian cancers. Germ cell tumors are the most common histologic type of ovarian cancer in children and adolescents. (See 'Fetuses, children, and adolescents' above.)

•Premenopausal patients – There is a broad differential diagnosis of an adnexal mass in patients of reproductive age. Adnexal masses stimulated by reproductive hormones are found almost exclusively in this age group. These include physiologic cysts (eg, follicular cyst, corpus luteal cyst), endometriomas, and leiomyomas. Ovarian or tubal malignant neoplasms are uncommon in this age group, although the peak age for ovarian germ cell tumors is between ages 10 and 30 years. (See 'Premenopausal patients' above.)

•Postmenopausal patients – There is a high index of suspicion for ovarian cancer in postmenopausal patients with an adnexal mass. At least 30 percent of ovarian masses in patients over age 50 are malignant neoplasms. Nonmalignant etiologies of an adnexal mass in postmenopausal patients include many of those also seen in patients of reproductive age. Simple cysts are common in this age group and are rarely malignant. (See 'Postmenopausal patients' above.)

●Nongynecologic masses – Nongynecologic sources of adnexal masses include metastatic disease from nongynecologic primary sites (eg, gastrointestinal, breast), pelvic abscess, and other pelvic or retroperitoneal masses (eg, peritoneal inclusion cyst, nerve sheath tumor, bladder diverticulum). (See 'Nongynecologic masses' above.)