Cholecystocutaneous Fistula

Etiology

Cholecysto-cutaneous fistulas present as an uncommon complication of neglected calculous cholecystitis. This condition has also been associated with acalculous cholecystitis or carcinoma of the gall bladder. A significant proportion of patients with this condition present with nonspecific symptoms and rarely disclose a history of previous gallbladder disease.[5] Once the gallbladder wall becomes inflamed, it can begin to necrotize if left untreated. Complete wall necrosis results in bile leakage into adjacent tissue. One potential site of leakage is the abdominal wall and, eventually, the overlying skin, resulting in a cholecysto-cutaneous fistula. 

Epidemiology

Due to the rarity of the condition, the available information is limited. The affected patients are usually older females. When questioned, patients may mention previous episodes of right upper quadrant pain. This pain hints at gallstone disease. The most common site of the fistulous opening is the right upper quadrant of the abdomen.

Painless, draining fistulas associated with this condition have been reported in many locations on the abdominal wall, including the right upper quadrant, right iliac fossa, umbilicus, right lumbar region, left lower quadrant, and even the gluteal region. Gallbladder fistulas have been known to occur following percutaneous treatment for acute cholecystitis and reoccurrence of cholecystitis, with the fistula forming along the previous track of the cholecystostomy drain.[6][7]

Pathophysiology

Obstruction of the biliary outflow by a gallstone is thought to play a significant role in the pathophysiology of the development of this condition. Obstruction of the cystic duct increases intra-gallbladder pressure. Unrelieved obstruction of bile outflow compromises blood circulation in the gallbladder wall and lymphatic drainage, eventually resulting in necrosis of the gallbladder wall. An open perforation of the gallbladder leads to a pericholecystic abscess. Once perforated, the gallbladder may drain into the peritoneal cavity, causing a localized peritoneal abscess.

This abscess can then develop into an external fistula due to its adherence to the abdominal wall. It expels its contents through an area of least resistance or the shortest route. Conditions such as polyarteritis nodosa, typhoid, trauma, or drug treatments such as steroids may be predisposing factors. Carcinoma of the gallbladder is known to present with an external fistula. Cutaneous gallbladder fistula is usually a late sequela of chronic biliary tract disease. It has also been reported after inadequate treatment of acute cholecystitis. 

History and Physical

The clinical presentation may vary depending on the underlying pathology, the patient's age, and the presence or absence of an associated abdominal wall abscess. The typical clinical presentation is a patient with a sinus persistently discharging bile. There is usually a history of chronic biliary tract disease, even though patients may not report it as a primary complaint. At times, the patient may report expulsion of gallstones through the fistula. The site of the external opening of the fistula is variable and depends on the anatomical course.

The most common site of the outer opening is the right upper quadrant of the abdominal wall. However, the opening of the fistula tract may be present in the left costal margin, right iliac fossa, right groin, or right gluteal region. Patients may be toxic with an acute infection or an associated abscess. The character of the discharge from the fistula may vary according to the underlying pathology. A lump may be palpable deep to the fistula due to the underlying inflamed or malignant gallbladder.

Evaluation

Ultrasonography is the first modality of imaging in the background of gallstone disease, but it has not been found to be of significant use in gallbladder fistula, even though it demonstrates the presence of gallstones reliably. A computed tomography (CT) scan is the most useful imaging modality for diagnosing this complication. CT imaging will reveal evidence of gallstones and communication to the gallbladder. A CT fistulogram can demonstrate the fistula connecting to the gallbladder and biliary tract, which is contributory to the establishment of this diagnosis. A CT fistulogram can be obtained by injecting diluted contrast through the fistulous tract during CT.

A CT fistulogram helps delineate the course of the tract accurately and establish its anatomical relationship. This imaging modality also helps exclude any internal fistula and other associated pathology. A clear delineation of the fistulous tract helps plan the surgical approach and extent. Routine blood tests may not be helpful unless there is an abscess collection. MRI with cholangiopancreatography has also proven useful in establishing the diagnosis.[8][9]

Treatment / Management

The management of cholecyst-cutaneous fistula requires initial drainage of any associated abscess and administration of appropriate antibiotics. If there is an associated mass, it is expedient to obtain a cytologic diagnosis by fine-needle aspiration cytology (FNAC) to exclude an underlying malignancy. If the cytology is negative or there is no suspicion of malignancy, the next step to follow is an elective cholecystectomy once the patient is stable and his or her general condition is optimized. An open cholecystectomy with excision of the fistulous tract is the definitive treatment. Laparoscopic cholecystectomy can be considered to reduce the morbidity since many of these patients will be older with multiple associated comorbidities.

Percutaneous treatment with removal of the gallstones only is reserved for the elderly with multiple comorbidities, or for those who are too debilitated to withstand surgery. Before the definitive surgery is performed, an effort must be made to ensure that there is no associated bile duct obstruction or stones. An indication of an unresectable disease is if a gallbladder fistula occurs in the setting of cancer with an associated dated mass. In this case, the overall outcome is dismal because gallbladder cancer has a predilection for seeding and spreading to the adjoining anatomical structures.[10][11](B3)

Differential Diagnosis

The differential diagnosis includes the following:

• Chronic osteomyelitis of the ribs
• Discharging tuberculoma
• Infected epidermal inclusion cyst
• Metastatic carcinoma
• Pyogenic granuloma

Prognosis

The prognosis of cholecystocutaneous fistula is generally good. Complications may occur in the elderly with underlying comorbid conditions. Malignant change of the fistulous tract is rare. 

Complications

Complications can include the following:

• Necrotizing fasciitis
• Skin irritation
• Malignant changes