Approach to the patient with an intertriginous skin disorder

INTRODUCTION — Intertriginous skin disorders are a diverse group of diseases that may occur as a manifestation of a variety of cutaneous and systemic diseases. The differential diagnosis includes a broad list of inflammatory, infectious, genetic, and other disorders, which often can be differentiated based upon clinical features. Diagnostic techniques, such as a potassium hydroxide preparation, Wood's lamp examination, culture, or skin biopsy, may also be useful.

The evaluation of intertriginous skin eruptions will be reviewed here. Intertrigo, one of the most common intertriginous skin disorders, is reviewed in detail separately. (See "Intertrigo".)

DEFINITION — Intertriginous skin, also known as skin folds, are sites in which opposing skin surfaces come into contact while at rest, resulting in chronic skin occlusion. The primary intertriginous skin areas include the groin folds, axillae, and gluteal cleft. Body habitus may contribute to additional intertriginous sites, such as inframammary skin and abdominal folds.  

PATIENT ASSESSMENT — The diagnosis of an intertriginous skin disorder begins with review of the patient history and a physical examination.

Helpful historical information may include:

●Patient age

●Associated symptoms

●Duration

●Clinical course (eg, chronic, episodic)

●Family history

●Medication exposure

●Comorbidities

●Response to prior therapies

The physical examination provides the foundation for the differential diagnosis. A complete skin examination should be performed, including careful examination of all intertriginous sites, the remaining skin, and nails.

Important features to assess include:

●Distribution

●Lesion morphology (papules, pustules, plaques, erosions, scale, etc) (see 'Morphology' below)

●Concomitant abnormalities of nonintertriginous skin and nails that suggest specific diseases (see 'Associated physical findings' below)

Additional testing is indicated when the diagnosis remains uncertain based upon the history and physical examination or testing is necessary to confirm a presumed diagnosis. Examples of commonly performed tests include:

●Potassium hydroxide preparation of disorders with scale to detect superficial fungal infections (see "Office-based dermatologic diagnostic procedures", section on 'Potassium hydroxide preparation')

●Wood's lamp examination of red to brown patches with fine or absent scale to detect erythrasma (see "Office-based dermatologic diagnostic procedures", section on 'Wood's lamp examination (black light)')

●Bacterial culture of pustular or blistering eruptions to detect infections and determine the causative organism

●Tzanck preparation and/or polymerase chain reaction (PCR) testing of grouped pustules or vesicles suspicious for herpes simplex virus infection or herpes zoster (see "Office-based dermatologic diagnostic procedures", section on 'Tzanck smear' and "Epidemiology, clinical manifestations, and diagnosis of genital herpes simplex virus infection" and "Epidemiology, clinical manifestations, and diagnosis of herpes zoster")

Skin biopsies are not usually necessary and are generally reserved for patients with an uncertain diagnosis or for whom pathologic examination is required to confirm the suspected diagnosis. The preferred type of biopsy to perform depends upon the differential diagnosis. A shave biopsy is adequate for evaluation of disorders with pathology primarily involving the epidermis and the superficial dermis; punch biopsies allow for examination of the epidermis and full thickness of the dermis. Direct immunofluorescence is indicated if the differential diagnosis includes an autoimmune blistering disorder, such as pemphigus vegetans. (See "Approach to the patient with cutaneous blisters", section on 'Skin biopsy' and "Skin biopsy techniques", section on 'Biopsy techniques'.)

MORPHOLOGY — Careful evaluation of the morphology of intertriginous skin disorders helps to narrow the differential diagnosis. Disorders characterized by erythematous patches or plaques, hyperpigmentation, pustules, blisters, erosions, ulceration, papules, verrucous or hyperkeratotic features, and nodules are reviewed below.

Erythematous patches or plaques — A wide variety of disorders may result in inflamed patches or plaques on intertriginous skin. Of note, erythema may be subtle in individuals with highly pigmented skin.

Common disorders — Careful examination for the presence of scale can facilitate diagnosis. Erythrasma, pityriasis rosea, seborrheic dermatitis, and tinea cruris may have associated scale, though scale generally is less prominent on intertriginous skin and may be absent. Scale is typically absent in intertrigo and inverse psoriasis.

Scale sometimes present

●Erythrasma – Erythrasma is a superficial corynebacterial infection that can present with erythematous to brown, well-defined patches or thin plaques in the skin folds (picture 1A-B). Fine scale and wrinkling often gives the skin a "cigarette paper" appearance. Affected areas may be asymptomatic or associated with mild pruritus. Examination with a Wood's lamp demonstrating coral red fluorescence or a Gram stain demonstrating gram-positive filaments and rods confirms the diagnosis (picture 2). (See "Erythrasma" and "Office-based dermatologic diagnostic procedures", section on 'Wood's lamp examination (black light)'.)

●Pityriasis rosea – Occasionally, pityriasis rosea can present as well-defined, dull pink to brown papules and plaques in the groin and axillae rather than the classic presentation (picture 3A-B). Onset is sudden, often beginning with an initial, larger herald patch. The fine, peripheral scale seen in classic pityriasis rosea plaques may be present or absent. Lesions are asymptomatic or minimally pruritic. Spontaneous resolution usually occurs within several weeks [1]. (See "Pityriasis rosea".)

●Seborrheic dermatitis – Involvement of the groin, axillae, and inframammary creases may occur in seborrheic dermatitis in infants and adults, manifesting as well-demarcated, moist, erythematous patches or plaques, often with associated greasy scale (picture 4A-C). Involvement of the scalp, facial creases, or postauricular creases usually accompanies intertriginous involvement, assisting with diagnosis [2]. (See "Seborrheic dermatitis in adolescents and adults" and "Cradle cap and seborrheic dermatitis in infants".)

●Tinea cruris – Tinea cruris is a superficial dermatophyte fungal infection of the groin skin folds and may extend to the lower abdomen, proximal thighs, and buttocks. Erythematous patches or plaques with peripheral scale are characteristic, but scale may also be minimal or absent (picture 5A-B). Tan or reddish-brown hyperpigmentation may also be seen centrally. Mild pruritus is common, and there is often concomitant tinea pedis or onychomycosis. The diagnosis can be confirmed with a potassium hydroxide preparation of scale that reveals large, branching hyphae (picture 6). (See "Dermatophyte (tinea) infections".)

Scale typically absent

●Intertrigo – Intertrigo is a common intertriginous dermatitis that usually results from friction and moisture within skin folds. Intertrigo appears as moist, dull red to red-brown patches or thin plaques (picture 7A-B). Pruritus is common and pain may occur if fissuring or erosion is present. Debilitation, infancy, and obesity are risk factors for intertrigo [3]. The diagnosis is made based upon the distribution limited to sites of friction and moisture and the exclusion of other disorders. (See "Intertrigo".)

Candidal or bacterial infections may be inciting or exacerbating factors. Features suggestive of candidal intertrigo are beefy red plaques with satellite papules and pustules (picture 8) (see 'Pustules' below). Often, satellite lesions demonstrate a collarette of scale. A potassium hydroxide preparation from the scale or pustule can be used to confirm candidal infection. Streptococcal intertrigo due to beta-hemolytic streptococcus usually presents with brightly erythematous patches and intense itching or burning (picture 9A-B) [4,5]. A bacterial culture confirms the diagnosis. (See 'Pustules' below and "Intertrigo".)

●Psoriasis – Inverse psoriasis presents as well-demarcated, erythematous plaques in the groin, the axillae, or inframammary creases (picture 10A-B). Unlike many other areas involved with psoriasis, thick scaling in inverse psoriasis is uncommon. Often, the surface of intertriginous lesions of psoriasis have a shiny appearance due to maceration. The presence of psoriatic involvement in other skin areas, such elbows and knees, or psoriatic nail abnormalities (eg, nail pits, oil spots, and distal onycholysis) can help distinguish inverse psoriasis. In addition, patients may have a family history of psoriasis. (See "Treatment of psoriasis in adults", section on 'Intertriginous psoriasis' and "Psoriasis: Epidemiology, clinical manifestations, and diagnosis", section on 'Inverse (intertriginous) psoriasis' and "Nail psoriasis".)

Less common disorders — Examples of less common disorders that may manifest with erythematous patches or plaques include extramammary Paget disease, Langerhans cell histiocytosis, lichen planus, symmetric drug-related intertriginous and flexural exanthema, and unilateral laterothoracic exanthem:

●Extramammary Paget disease – Extramammary Paget disease may present as well-demarcated, erythematous plaques on genital or perianal skin or the perineum. The plaques may exhibit crusting, erosions, lichenification, or a verrucous surface (picture 11A-B). Pruritus is common. The diagnosis should be suspected when patients fail to respond to treatment for a presumed diagnosis as expected. A biopsy is necessary to confirm the diagnosis. (See "Vulvar cancer: Epidemiology, diagnosis, histopathology, and treatment", section on 'Paget disease of the vulva'.)

●Langerhans cell histiocytosis – Langerhans cell histiocytosis is a potentially life-threatening disorder that can present in infancy or early childhood with red-orange or yellow-brown papules, plaques, erosions, and petechiae on the scalp, groin, or intertriginous regions (picture 12). A skin biopsy is necessary to confirm the diagnosis. (See "Clinical manifestations, pathologic features, and diagnosis of Langerhans cell histiocytosis".)

●Lichen planus – Inverse lichen planus, also referred to as lichen planus pigmentosus inversus, is a rare, pruritic dermatosis that affects the axillae and groin. Affected patients develop asymptomatic or mildly pruritic, discrete, erythematous to violaceous patches and plaques that follow skin cleavage lines (picture 13). Hyperpigmentation is a striking feature. Middle-aged adults are most commonly affected. Classic lichen planus on areas such as the shins and wrists may also be present. Mucosal involvement is generally absent [6]. A skin biopsy reveals a band-like infiltrate of lymphocytes at the base of an atrophic epidermis. Pigment incontinence is a prominent histologic feature. (See "Lichen planus".)

●Symmetric drug-related intertriginous and flexural exanthema – Symmetric drug-related intertriginous and flexural exanthema is a medication reaction that presents as well-demarcated, erythematous patches affecting at least one flexural area. The onset is acute, and there is history of recent exposure to one of a wide variety of potential inciting medications. The diagnosis is made based on history, clinical suspicion, and improvement upon stopping the offending medication. (See "Drug eruptions", section on 'Symmetrical drug-related intertriginous and flexural exanthema'.)

●Unilateral laterothoracic exanthem – Unilateral laterothoracic exanthem is a viral exanthema that typically occurs in young children. It generally begins as a unilateral, morbilliform exanthema in or adjacent to one axilla and may also begin in the groin (picture 14). Mild pruritus is common. Progression to the other side of the body often occurs. The diagnosis is made based upon the clinical appearance. Complete resolution within five weeks is expected [7]. (See "Atypical exanthems in children", section on 'Unilateral laterothoracic exanthem'.)

Hyperpigmentation — Examples of disorders of intertriginous sites with hyperpigmentation as a primary feature include acanthosis nigricans, confluent and reticulated papillomatosis, and Dowling-Degos disease. Hyperpigmentation may also occur as a secondary effect of any cutaneous inflammatory disorder (postinflammatory hyperpigmentation), particularly in individuals with moderately to highly pigmented skin (see 'Erythematous patches or plaques' above):

●Acanthosis nigricans – Acanthosis nigricans is a common disorder that usually presents as velvety, brownish, asymptomatic plaques on the neck and/or intertriginous skin (picture 15A-B). The disorder is associated with obesity and insulin resistance [8]. Rarely, acanthosis nigricans is associated with malignancy. The physical examination is usually sufficient for diagnosis. (See "Acanthosis nigricans".)

●Confluent and reticulated papillomatosis – Confluent and reticulated papillomatosis (CARP) presents as erythematous to dark brown, net-like patches involving the trunk, neck, and axillae (picture 16A-B). CARP typically occurs in young adults and is asymptomatic in most patients. The diagnosis usually can be made based upon the physical findings and the exclusion of tinea versicolor with a potassium hydroxide preparation. (See "Confluent and reticulated papillomatosis".)

●Dowling-Degos disease – Dowling-Degos disease (reticulate pigmented anomaly of flexures) is a rare autosomal dominant disease that typically presents in adulthood as reticular hyperpigmentation involving the intertriginous skin, neck, and inner aspects of the arms and thighs (picture 17). Pruritus is common. The diagnosis is made based upon the clinical appearance and a skin biopsy demonstrating increased pigment in the basal layer of the epidermis and finger-like rete ridges with thinning of the suprapapillary epithelium. Galli-Galli disease is an autosomal dominant disorder that is considered an allelic variant of Dowling-Degos disease that has similar clinical and histologic features but also exhibits suprabasal acantholysis. (See "Congenital and inherited hyperpigmentation disorders", section on 'Dowling-Degos disease'.)

Pustules — Cutaneous disorders with intertriginous pustules as a common feature include amicrobial pustulosis of the folds, folliculitis, candidal intertrigo, pemphigus vegetans, and subcorneal pustular dermatosis:

●Amicrobial pustulosis of the folds – Amicrobial pustulosis of the folds is rare and occurs most often in young women and in association with autoimmune diseases. Patients develop recurrent eruptions of follicular and nonfollicular sterile pustules that exhibit a predilection for intertriginous skin, scalp, and periorificial areas on the head (mouth, nostrils, ear canals). The diagnosis is based upon the clinical findings as well as the exclusion of infection and other disorders. (See "Neutrophilic dermatoses", section on 'Amicrobial pustulosis of the folds'.)

●Bacterial folliculitis – Bacterial folliculitis presents with multiple follicular pustules and erythematous papules. Pruritus is common. Staphylococcus aureus is a frequent causative organism. The diagnosis usually can be made based upon the physical examination. (See "Infectious folliculitis", section on 'Bacterial folliculitis'.)

●Candidal intertrigo – Candidal intertrigo is an intertriginous fungal skin infection caused primarily by Candida albicans [9]. The typical manifestations consist of beefy red plaques with delicate, peripheral pustules (picture 8). The pustules may present as superficial erosions due to their fragile nature. Itching and burning are frequent symptoms. A potassium hydroxide preparation demonstrating yeast, hyphae, and pseudohyphae confirms the diagnosis (picture 18). (See "Intertrigo" and "Office-based dermatologic diagnostic procedures", section on 'Potassium hydroxide preparation'.)

●Pemphigus vegetans – Pemphigus vegetans is a variant of pemphigus that may present with vegetative plaques on intertriginous skin (picture 19). Pustules may precede the development of the vegetative plaques (picture 20). Pemphigus vegetans is reviewed below. (See 'Verrucous or hyperkeratotic papules or plaques' below.)

●Subcorneal pustular dermatosis – Subcorneal pustular dermatosis is a rare disorder that presents as an extensive eruption of fragile, sterile pustules favoring intertriginous areas, such as the groin and axillae (picture 21). An annular or serpiginous distribution is common. There is significant clinical overlap between subcorneal pustular dermatosis and variants of immunoglobulin A (IgA) pemphigus [10]. IgA pemphigus is less likely to involve intertriginous skin, and a skin biopsy with direct immunofluorescence helps to distinguish between these diagnoses. (See "Subcorneal pustular dermatosis" and "Pathogenesis, clinical manifestations, and diagnosis of pemphigus", section on 'IgA pemphigus'.)

Blisters, erosions, or ulcers — Intertriginous erosions can be prominent in bullous impetigo and Hailey-Hailey disease and may also occur as secondary lesions in other disorders, such as Langerhans cell histiocytosis and pustular diseases. Ulcers may occur in the setting of metastatic Crohn disease or sexually transmitted diseases:

●Herpetic infections – Herpes zoster and herpes simplex virus infection can present as grouped vesicles, erosions, or pustules. Sites of involvement are typically unilateral and may be painful or itchy. Polymerase chain reaction (PCR) testing for varicella zoster virus and herpes simplex virus is useful for distinguishing between these disorders and confirming the diagnosis. (See "Epidemiology, clinical manifestations, and diagnosis of genital herpes simplex virus infection" and "Epidemiology, clinical manifestations, and diagnosis of herpes zoster".)

●Bullous impetigo – Bullous impetigo is a cutaneous infection caused by S. aureus strains that produce an exfoliative toxin, resulting in superficial blisters. Intact blisters are rare, as they are often denuded by friction. The more common findings are superficial erosions associated with background erythema and golden or "honey" crusts (picture 22A-B). The face, extremities, groin, axillae, and neck are common sites [11]. The diagnosis can be made based upon the clinical appearance and confirmed with Gram stain and culture. (See "Impetigo".)

●Hailey-Hailey disease – Hailey-Hailey disease (benign familial pemphigus) is a rare autosomal dominant, intraepidermal blistering disorder that presents as painful blisters, erosions, and maceration in intertriginous areas (picture 23A-B) [12]. Onset usually occurs after puberty. Skin biopsy confirms the diagnosis and demonstrates acantholysis of the epidermis. (See "Hailey-Hailey disease (benign familial pemphigus)".)

●Metastatic Crohn disease – Metastatic Crohn disease may present as deep, jagged ulcerations in the inguinal creases, often with associated genital swelling (picture 24) [13]. Skin lesions may occur before or after development of gastrointestinal disease. A punch biopsy reveals noncaseating granulomas in the dermis.

Various sexually transmitted infectious diseases may cause ulcers in the genital region or groin. This differential diagnosis is reviewed separately. (See "Approach to the patient with genital ulcers".)

Discrete papules — Discrete papules on intertriginous skin occur in patients with acrochordons, Fox-Fordyce disease, and pseudoxanthoma elasticum:

●Acrochordons – Acrochordons, also known as skin tags, are benign skin growths that appear as soft, pedunculated papules and most often occur on the axillae, neck, groin, and inframammary regions (picture 25A-B). The diagnosis typically can be made based upon the clinical appearance. (See "Overview of benign lesions of the skin", section on 'Acrochordon (skin tag)'.)

●Fox-Fordyce disease – Fox-Fordyce disease (apocrine miliaria) is an inflammatory disease that predominantly occurs in young adult women. It typically presents as pruritic papules in the axillary vaults, although it has been reported on other areas rich in apocrine glands, such as the areola and the vulva. Occlusion of the apoeccrine sweat ducts is thought to cause the eruption (picture 26A-B) [14]. The diagnosis can usually be made based upon the clinical appearance. (See "Fox-Fordyce disease (apocrine miliaria)".)

●Pseudoxanthoma elasticum – Pseudoxanthoma elasticum is an autosomal recessive disease that results in abnormal elastic tissue [15-17]. The classic cutaneous findings are collections of yellow papules in flexural areas, such as the sides of the neck, antecubital fossae, axillae, and groin (picture 27) [18]. The papules are asymptomatic and may be detected incidentally. Skin biopsy confirms the diagnosis. Patients with pseudoxanthoma elasticum are at risk for cardiovascular and ocular complications. (See "Pseudoxanthoma elasticum".)

Verrucous or hyperkeratotic papules or plaques — Verrucous or hyperkeratotic papules or plaques on intertriginous skin may be indicative of condylomata acuminata, condylomata lata, granular parakeratosis, or pemphigus vegetans:

●Condylomata acuminata – Condylomata acuminata, caused by human papilloma virus infection, may present as soft, verrucous plaques on the external genitalia, perianal skin, perineum, groin, or lower abdomen (picture 28A-C). The physical examination is usually sufficient for diagnosis. A skin biopsy can confirm the diagnosis when the diagnosis is uncertain. (See "Condylomata acuminata (anogenital warts) in adults: Epidemiology, pathogenesis, clinical features, and diagnosis".)

●Condylomata lata – Condylomata lata are a manifestation of secondary syphilis characterized by the development of moist, warty plaques on perianal, perivaginal, or inguinal skin (picture 29). Condylomata lata contain large numbers of spirochetes and are highly infectious. The diagnosis is usually made through serologic testing for syphilis. A skin biopsy can be useful for differentiating condylomata lata from other skin lesions. Dark field microscopy and PCR diagnostic tests may be available in specialized centers. (See "Syphilis: Epidemiology, pathophysiology, and clinical manifestations in patients without HIV".)

●Granular parakeratosis – Granular parakeratosis presents as pink to brown, hyperkeratotic papules that coalesce into plaques (picture 30A-B). The disorder most commonly affects the axillae of women but may also occur in other intertriginous areas and in men or children [19,20]. Pruritus is common. A biopsy can confirm the diagnosis. The name of this disorder reflects the histologic pattern observed on skin biopsy [21]. (See "Granular parakeratosis".)

●Pemphigus vegetans – Pemphigus vegetans is an immunobullous disease and a variant of pemphigus vulgaris. It can present as macerated, warty plaques involving intertriginous areas (picture 19) [22]. Blisters and erosions may not be evident. A skin biopsy with direct immunofluorescence can confirm the diagnosis. (See "Pathogenesis, clinical manifestations, and diagnosis of pemphigus".)

●Seborrheic keratoses – Seborrheic keratoses are common, benign epidermal tumors that typically arise during adulthood. Characteristic clinical features are well-demarcated, hyperpigmented, round or oval papules or plaques with a verrucous surface and stuck-on appearance (picture 31A-B). In addition, seborrheic keratoses have visible keratin plugs. Common intertriginous locations for seborrheic keratoses are the inframammary skin and abdominal folds. (See "Overview of benign lesions of the skin", section on 'Seborrheic keratosis'.)

Nodules — Cutaneous nodules on intertriginous skin may occur in patients with furunculosis or hidradenitis suppurativa:

●Furunculosis – Furuncles, also known as boils, are perifollicular, cutaneous abscesses that occur in sites of hair follicles. S. aureus infection is the most common cause. Furuncles appear as painful, inflamed nodules that may be fluctuant and may drain purulent material. (See "Cellulitis and skin abscess: Epidemiology, microbiology, clinical manifestations, and diagnosis", section on 'Skin abscess'.)

●Hidradenitis suppurativa – Hidradenitis suppurativa is a chronic inflammatory disorder that is characterized by recurrent, inflamed nodules, abscesses, and comedones on intertriginous skin (picture 32). The disease may progress to sinus tract formation and severe, rope-like scarring. The axillae, groin, and inframammary areas are among the most common sites of involvement. The patient history and physical findings support the diagnosis. (See "Hidradenitis suppurativa: Pathogenesis, clinical features, and diagnosis".)

AGE — Review of the typical age distribution of specific disorders may help to narrow the differential diagnosis. The disorders often responsible for intertriginous eruptions in infants and children are listed below. These disorders are not exclusive to children and may also occur in adolescents and adults.

Infants — Intertriginous disorders often in the differential diagnosis for infants include:

●Bullous impetigo

●Intertrigo

●Langerhans cell histiocytosis

●Seborrheic dermatitis

●Psoriasis

Prepubertal children — Intertriginous disorders often in the differential diagnosis for prepubertal children include:

●Acanthosis nigricans

●Bullous impetigo

●Condylomata acuminata

●Pityriasis rosea

●Psoriasis

●Unilateral thoracic exanthem

SYMPTOMS — Associated symptoms, such as pruritus and pain, may help to narrow the differential diagnosis.

Pruritus — Prominent pruritus may occur in association with:

●Bacterial folliculitis

●Dowling-Degos disease

●Extramammary Paget disease

●Fox-Fordyce disease

●Granular parakeratosis

●Intertrigo

●Tinea cruris

Pain — Pain is a common symptom in patients with:

●Metastatic Crohn disease

●Furunculosis

●Hailey-Hailey disease

●Hidradenitis suppurativa

●Intertrigo with fissuring

●Pemphigus vegetans

FAMILY HISTORY — Patients with psoriasis and autosomal dominant disorders, such as Dowling-Degos disease and Hailey-Hailey disease, may report similar symptoms in family members, assisting with diagnosis.

OTHER HISTORY — Information regarding the clinical course, medication exposure, and response to previous treatments may facilitate diagnosis. For example, an acute onset is typical of bacterial folliculitis, bullous impetigo, furunculosis, and symmetric drug-related intertriginous and flexural exanthemata, in contrast to the chronic and relapsing course that characterizes hidradenitis suppurativa, subcorneal pustular dermatosis, amicrobial pustulosis of the folds, and other disorders. The medication exposure history may indicate susceptibility to intertriginous infections due to immunosuppression or exposure to drugs associated with symmetric drug-related intertriginous and flexural exanthemata. Failure to respond to topical corticosteroids or other therapies as expected may result in a shift in the presumed diagnosis, such as from psoriasis to extramammary Paget disease.

ASSOCIATED PHYSICAL FINDINGS — An examination for additional physical findings can help to support a diagnosis.

Skin abnormalities — Knowledge of current or prior characteristic nonintertriginous skin lesions may be helpful. Examples include:

●Lichen planus – Violaceous, polygonal, intensely pruritic papules or plaques on the extremities, particularly wrists and ankles

●Pityriasis rosea – Numerous oval, erythematous plaques with peripheral collarettes of scale, often following the initial appearance of a larger, similar "herald patch"

●Psoriasis – Erythematous plaques with thick, silvery scale on the scalp, trunk, or extremities

●Seborrheic dermatitis – Greasy scale involving the scalp, nasolabial folds, eyebrows, or postauricular skin

●Syphilis – History of painless chancre, diffuse macular or papular eruption including palms and soles, or alopecia

Nail abnormalities — Nail abnormalities may occur in association with certain intertriginous skin disorders. Examples include:

●Hailey-Hailey disease – Longitudinal white bands

●Lichen planus – Longitudinal ridging, nail plate thinning, longitudinal fissuring, trachyonychia, erythema of the lunula, hyperpigmentation, onycholysis (see "Overview of nail disorders", section on 'Lichen planus')

●Psoriasis – Pitting, oil drop discoloration, onycholysis, subungual hyperkeratosis, nail plate crumbling, other findings (see "Nail psoriasis")

SUMMARY AND RECOMMENDATIONS

●Definition of intertriginous areas – Intertriginous skin areas are sites in which opposing skin areas come into contact while at rest leading to chronic skin occlusion. Examples include the axillae, groin folds, and gluteal cleft. The presence of additional intertriginous areas, such as inframammary skin and abdominal folds, is dependent on body habitus. (See 'Definition' above.)

●Intertriginous skin disorders – Intertriginous skin disorders are a diverse group of inflammatory, infectious, genetic, and other disorders and exhibit a wide variety of clinical features.

●Patient assessment – Many intertriginous disorders can be diagnosed based upon the patient history and physical examination (see 'Patient assessment' above):

•History – Important diagnostic information may include the patient age, associated symptoms, and family history. (See 'Age' above and 'Symptoms' above and 'Family history' above and 'Other history' above.)

•Physical examination – The physical examination should include an assessment of the distribution and morphology of the intertriginous skin disorder. In addition, examination of the entire skin surface and nails should be performed to identify other findings suggestive of specific diseases. (See 'Morphology' above and 'Associated physical findings' above.)

•Additional tests – When the history and physical examination are insufficient for diagnosis, tests such as potassium hydroxide preparation, Wood's lamp examination, culture, and skin biopsy may help with diagnosis. (See 'Patient assessment' above.)