Porcelain gallbladder

INTRODUCTION AND TERMINOLOGY — 

Porcelain gallbladder is calcification of the gallbladder wall [1]. The term porcelain gallbladder has been used to describe the bluish discoloration and brittle consistency of the gallbladder wall associated with this condition [2]. It is associated with chronic gallbladder inflammation, and approximately 95 percent of patients have associated gallstones. Patients with a porcelain gallbladder are often asymptomatic. The diagnosis is usually made incidentally on abdominal imaging. Porcelain gallbladder is associated with an increased risk for gallbladder cancer, but the magnitude of risk appears to be small.

This topic will review the epidemiology, clinical presentation, diagnosis, and management of porcelain gallbladder. Gallbladder cancer, uncomplicated gallstone disease, acalculous cholecystitis, and acute cholecystitis are discussed separately. (See "Epidemiology, risk factors, clinical features, and diagnosis of gallbladder cancer" and "Clinical manifestations and evaluation of gallstone disease in adults" and "Choledocholithiasis: Clinical manifestations, diagnosis, and management" and "Acalculous cholecystitis".)

SUBTYPES

Porcelain gallbladder is classified based upon the extent of calcification [3]:

●Complete intramural calcification – A continuous band of calcium infiltrates and replaces the muscular layer of the gallbladder wall. It is accompanied by sloughing of the mucosal epithelium and dense fibrosis of the entire gallbladder wall. This appears radiologically as large plaque-like areas.

●Selective mucosal calcification – Calcification of the gallbladder wall is less extensive or segmental with flecks of calcium in the glandular spaces of the mucosa. This pattern results in the radiographic appearance of granular calcification (picture 1).

EPIDEMIOLOGY

Incidence — Porcelain gallbladder is rare and is detected in 0.06 to 0.2 percent of cholecystectomy specimens [4,5]. It has a female preponderance (5:1) and is usually diagnosed in the sixth decade of life [6].

Risk of malignancy

●Prevalence – The prevalence of gallbladder carcinoma in patients with porcelain gallbladder is approximately 2 to 6 percent according to a number of systematic reviews [5,7-9]. Most of these studies reported only the presence of carcinoma at the time of diagnosis. In one study of 90 patients, 6 percent had gallbladder cancer at the time of diagnosis [9]. None were known to develop malignancy during the follow-up period (6.6 ± 4.6 years), however, it is not clear that patients were systematically evaluated for malignancy during follow-up.

●Differential risk by subtype – Patients with selective mucosal calcification of the gallbladder wall appeared to be at higher risk for gallbladder cancer compared with those in whom the gallbladder wall is completely calcified (complete type) [2-5,10-12]. In a series of 44 patients with gallbladder calcification who underwent cholecystectomy, 17 had complete intramural calcification, and 27 had selective (incomplete) mucosal calcification [11]. Gallbladder cancer was present in two of the patients with selective mucosal calcification (7 percent) and in none of the patients with complete calcification. A 2013 systematic review showed no difference in cancer risk between those with mucosal calcification and those with intramural calcification, but did show a higher risk of cancer in those with focal (rather than diffuse) calcification [7].

A potential explanation for the difference in the risk of gallbladder cancer is that gallbladder cancer is mucosal in origin and patients with the complete type of porcelain gallbladder have a low risk due to loss of mucosal epithelium. (See 'Subtypes' above and 'Ultrasound' below.)  

●Cancer type – The most common type of malignancy associated with porcelain gallbladder is adenocarcinoma, which is seen in nearly 80 percent of patients with porcelain gallbladder who develop gallbladder cancer [13]. Squamous cell carcinoma and adenosquamous carcinoma have also been reported. (See "Epidemiology, risk factors, clinical features, and diagnosis of gallbladder cancer".)

PATHOGENESIS — 

The pathogenesis of gallbladder wall calcification is uncertain. More than 95 percent of patients with porcelain gallbladder have gallstones [10]. It has been suggested that the chronic inflammation due to gallstones results in scarring, hyalinization, and calcification [6]. An alternative hypothesis is that cystic duct obstruction leads to bile stagnation within the gallbladder followed by mucosal precipitation of calcium carbonate salts [10].  

CLINICAL PRESENTATION

Incidental imaging finding — In most cases, porcelain gallbladder is asymptomatic and is found incidentally on abdominal imaging (abdominal radiographs, ultrasound, or abdominal computed tomography [CT] scan). Occasionally patients present with symptoms of the associated gallstones.

Abdominal radiographs — Plain abdominal radiographs may reveal curvilinear or rim-like calcifications in the gallbladder wall (image 1) [4]. However, similar findings can also be seen if the gallbladder is full of bile that is supersaturated with calcium salts (milk of calcium bile) or due to calcifications in gallstones, and degenerative cystic lesions of the pancreas. Hence, radiographs are not diagnostic for porcelain gallbladder due to their low sensitivity and specificity.

Ultrasound — The sonographic appearance of porcelain gallbladder depends on the extent of calcification:

●When the gallbladder wall is heavily calcified and the wall is diffusely involved, calcification appears as an echogenic arc with clean posterior acoustic shadowing.

●Less extensive calcification results in partial shadowing such that the posterior wall of the gallbladder remains visible. In early cases, only segments of the gallbladder wall may be affected.

Three distinct sonographic patterns have been described in patients with porcelain gallbladder [4]:

●Type I – A hyperechoic semilunar appearance with posterior acoustic shadowing (image 2).

●Type II – A biconvex curvilinear echogenic appearance with variable acoustic shadowing.

●Type III – Irregular clumps of echoes with posterior acoustic shadowing.

Type I corresponds to the complete intramural calcification. Type II and III correspond to selective mucosal calcification. (See 'Subtypes' above.)

Computed tomography — On abdominal CT scan in patients with porcelain gallbladder, the gallbladder wall appears as a calcified rim with a dark central bile-filled region (image 3).

Symptomatic presentation — A minority of patients (30 percent or less ) present with symptoms due to complications of the associated gallstone/gallbladder disease [14,15]. These include right upper quadrant/epigastric abdominal pain, jaundice, or fever due to common duct obstruction, cholangitis, or pancreatitis. (See "Clinical manifestations and evaluation of gallstone disease in adults".)

Rarely, the gallbladder may be palpable as a firm, nontender mass in the right upper quadrant [16].

DIAGNOSTIC IMAGING — 

Diagnostic imaging, usually CT scan, is performed in patients with suspected porcelain gallbladder to confirm the diagnosis and to exclude gallbladder cancer. Radiographs may suggest the diagnosis but are not diagnostic for porcelain gallbladder due to their low sensitivity and specificity. The diagnosis of porcelain gallbladder can be made based on ultrasound, but cross-sectional imaging (CT or magnetic resonance [MR]) is needed to rule out gallbladder cancer. (See 'Exclude cancer' below.)

The accuracy of CT scan in diagnosing porcelain gallbladder was evaluated in a study that evaluated 133 cases that were initially reported as porcelain gallbladder [9]. Radiology was reviewed by two independent radiologists and the diagnosis was confirmed by surgery/pathology or follow-up imaging. The diagnosis of porcelain gallbladder was confirmed in 90 of 133 cases (68 percent); thirty-two percent were false-positive. Misleading causes included stones filling the whole gallbladder lumen (91 percent), sludge (7 percent), and mucosal enhancement (5 percent). Six percent of cases had concurrent gallbladder cancer at the outset. (See "Epidemiology, risk factors, clinical features, and diagnosis of gallbladder cancer", section on 'Computed tomography and magnetic resonance imaging'.)

Specific findings seen on imaging studies are described above. (See 'Incidental imaging finding' above.)

DIFFERENTIAL DIAGNOSIS — 

The differential diagnosis of porcelain gallbladder on imaging includes cholelithiasis and emphysematous cholecystitis. These entities can be distinguished based on abdominal ultrasound. However, in some cases, abdominal CT may be required.

●Cholelithiasis – A stone-filled gallbladder is another cause of shadowing in the gallbladder fossa. However, in patients with cholelithiasis there is a thin hypoechoic bile space between the gallbladder wall and the gallstone echo. The presence of a wall echo shadow complex is suggestive of a stone-filled collapsed gallbladder. (See "Clinical manifestations and evaluation of gallstone disease in adults", section on 'Clinical manifestations'.)

●Emphysematous cholecystitis – Patients with emphysematous cholecystitis may also have an echogenic crescent in the gallbladder fossa. Ring-down shadows from gas within the gallbladder wall on ultrasound can mimic calcification in patients with porcelain gallbladder. However, emphysematous cholecystitis produces dirty acoustic shadowing.

MANAGEMENT — 

The management of porcelain gallbladder is controversial. Historically, porcelain gallbladder has generally been seen as an indication for cholecystectomy, even in asymptomatic patients. However, given that the risk appears to be lower than previously thought, some experts suggest that patients with porcelain gallbladder be observed, with surgery being reserved for those with conventional indications for cholecystectomy [5,17]. Others experts have challenged this recommendation, noting that the rate of gallbladder cancer seen in more recent studies (2 to 6 percent) is high enough to justify prophylactic cholecystectomy [18]. (See "Epidemiology, risk factors, clinical features, and diagnosis of gallbladder cancer" and 'Epidemiology' above and "Laparoscopic cholecystectomy", section on 'Indications'.)

Exclude cancer — For patients in whom porcelain gallbladder is suspected based on an radiograph or diagnosed on ultrasound, we perform an abdominal CT because it has a high sensitivity for calcification and gallbladder cancer [4]. Findings suggestive of gallbladder cancer that may be visualized on abdominal CT include a polypoid mass protruding into the lumen or completely filling it, focal or diffuse thickening of the gallbladder wall, or a mass in the gallbladder fossa with the gallbladder itself being indiscernible; liver invasion, suspected nodal involvement, or distant metastases may be seen [4].

While MRI is less sensitive for calcifications, it is an alternative for ruling out gallbladder cancer in patients in whom porcelain gallbladder is diagnosed on ultrasound. (See "Epidemiology, risk factors, clinical features, and diagnosis of gallbladder cancer", section on 'Computed tomography and magnetic resonance imaging'.)  

Further evaluation and management of patients with gallbladder cancer is discussed separately. (See "Epidemiology, risk factors, clinical features, and diagnosis of gallbladder cancer" and "Surgical management of gallbladder cancer".)

Indications for surgery

Symptomatic patients — We refer patients for cholecystectomy if they are symptomatic. Symptoms or complications of gallstone/gallbladder disease include biliary-type pain, common duct obstruction, cholangitis, or recurrent pancreatitis. (See "Clinical manifestations and evaluation of gallstone disease in adults".)

Asymptomatic patients — We suggest cholecystectomy for asymptomatic patients with porcelain gallbladder given their increased risk for gallbladder cancer. Limited data suggest that selective mucosal calcification is associated with a higher risk of malignancy compared to complete mural calcification. While the incidence of future cancer is uncertain, the prognosis for gallbladder cancer is poor. (See "Adjuvant therapy for localized resected gallbladder cancer", section on 'Prognosis and patterns of spread'.)

Surgical technique — Laparoscopic cholecystectomy is feasible in patients with porcelain gallbladder despite the presence of a fibrotic gallbladder wall, especially in patients with a long cystic duct and well-defined biliary anatomy [19,20]. Dissection can initially be performed laparoscopically with the plan to convert to an open procedure if necessary [21].

The surgeon should maintain a high index of suspicion for gallbladder cancer. A frozen section should be performed of any suspicious areas of the gallbladder to help the surgeon determine if an extended (radical) cholecystectomy should be done. The management of gallbladder cancer is discussed in detail, separately. (See "Surgical management of gallbladder cancer".)

Nonsurgical management — Patients with porcelain gallbladder who do not undergo cholecystectomy (due to either patient preference or patient's age and comorbid medical conditions) should be educated about the symptoms of gallstone/gallbladder disease and its complications and instructed to seek medical attention if the symptoms occur. If imaging of the gallbladder is indicated, we perform contrast-enhanced CT. Abdominal ultrasound is limited by gallbladder wall calcifications, which obscure the gallbladder contents. (See 'Symptomatic presentation' above.)

We do not routinely screen for gallbladder cancer [22]. In our experience, patients who do not undergo cholecystectomy are generally those with limited life expectancy due to comorbidities and advanced age, and therefore screening would not be of benefit.

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: Cholecystitis and other gallbladder disorders".)

SUMMARY AND RECOMMENDATIONS

●Definition and subtypes – Porcelain gallbladder is calcification of the gallbladder wall. Calcification may be limited to the mucosa or extend through the muscular layer. (See 'Subtypes' above.)

●Risk of malignancy – Porcelain gallbladder is associated with an approximately 2 to 6 percent risk of gallbladder cancer at the time of diagnosis. Cancer is more commonly found in patients with incomplete or selective calcification compared to those with complete calcification.

The incidence of cancer after diagnosis is uncertain. (See 'Risk of malignancy' above.)

●Clinical presentation – Porcelain gallbladder is usually asymptomatic and found incidentally on imaging.

In about one-third of cases, patients present with symptoms of gallbladder disease, such as right upper quadrant abdominal pain. (See 'Clinical presentation' above.)

●Diagnosis – Diagnostic imaging is performed in patients with suspected porcelain gallbladder to confirm the diagnosis and to exclude gallbladder cancer. The diagnosis of porcelain gallbladder can be made based on ultrasound, but cross-sectional imaging (CT or MR) is needed to rule out gallbladder cancer. (See 'Diagnostic imaging' above.)

●Management

•Excluding cancer – Upon diagnosis of porcelain gallbladder, cross-sectional imaging (CT with contrast or MRI with contrast) should be performed to rule out gallbladder carcinoma. (See 'Exclude cancer' above.)

•Symptomatic patients – Patients with biliary-type pain or complications of gallstones should undergo cholecystectomy. (See 'Symptomatic patients' above.)

•Asymptomatic patients – We suggest cholecystectomy for patients with porcelain gallbladder (Grade 2C) in order to reduce the risk of cancer. While the incidence of future cancer is uncertain, the prognosis for gallbladder cancer is poor. It is reasonable to defer surgery in patients who are not good surgical candidates. (See 'Asymptomatic patients' above.)