Gallbladder Mucocele 

Mucocele, or hydrops, of the gallbladder describes an overdistended gallbladder filled with mucoid or clear and watery content, as shown in the image below. The condition can result from gallstone disease, the most common affliction of the biliary system. Gallstone disease affects 15-20% of the US population, with nearly 1 million new cases reported annually.^{[1, 2, 3]}

The gallbladder mucocele distension, which is usually noninflammatory, results from an outlet obstruction of the gallbladder and is commonly caused by an impacted stone in the neck of the gallbladder or in the cystic duct, as illustrated in the images below.^{[1, 2, 4, 5]}

Frequency

About 3% of all pathologic gallbladders in adults are mucoceles. The true prevalence may be higher because of the varying criteria used by different authors to define the condition.^{[1, 2, 6]}

Reports indicate that an association could exist between mucoceles and solitary stones of the gallbladder.^[7]

Causes of gallbladder mucocele include the following:

• Impacted stone in the gallbladder neck or cystic duct
• Spontaneously resolved acute cholecystitis
• Tumors - Polyps or malignancy of the gallbladder
• Extrinsic compression of the neck or cystic duct by lymph nodes or inflammatory fibrosis or by adjacent malignancies in the liver, duodenum, or colon
• Prolonged total parenteral nutrition or ceftriaxone therapy
• Congenital narrowing of the cystic duct
• Parasites, such as Ascaris (occasionally)

In infants and children, acute, acalculous, noninflammatory hydrops of the gallbladder may be associated with the following:

• Kawasaki syndrome (mucocutaneous lymph node syndrome)^[8]
• Streptococcal pharyngitis
• Mesenteric adenitis
• Typhoid
• Leptospirosis
• Hepatitis
• Familial Mediterranean fever
• Nephrotic syndrome
• Fibrocystic disease

Other problems to be considered include the following:

• Hepatomegaly, choledochal cyst
• Courvoisier gallbladder due to simultaneous obstruction of the gallbladder and common bile duct
• Pseudocyst of the pancreas
• Renal mass
• Right suprarenal gland mass
• Mesenteric cysts
• Parasitic cysts - Hydatid cyst
• Ascending colon mass

Long-standing obstruction to the gallbladder's outflow results in overdistension of the gallbladder; occasionally, the gallbladder assumes massive proportions, and the volume may be as much as 1.5 liters. The bile or bile pigment is slowly resorbed, and continuing secretion from the mucosa of the gallbladder results in clear and watery or mucoid content (white bile). The gallbladder wall may be of normal thickness, although in long-standing cases, the mucosa atrophies and the wall becomes thin, sometimes even transparent. Wall thickening can occur with recurrent attacks of cholecystitis. The contents are usually sterile, and any bacterial contamination ends in empyema of the gallbladder. Gross overdistension may result in gangrene and/or perforation of the gallbladder, with ensuing pericholecystic collection or peritonitis. The severity of the inflammatory episode dictates the clinical presentation, as illustrated in the images below.

Microscopic examination reveals a flattened mucosa lined by low columnar or cuboidal cells; the increased intraluminal pressure results in plentiful Rokitansky-Aschoff sinuses. Inflammatory cells may be present either in small numbers or in abundance.^{[1, 2, 4]}

Symptomatology of a gallbladder mucocele includes right upper quadrant (RUQ) pain or epigastric pain and discomfort, nausea, and vomiting. Continuance of pain or persistence of tenderness longer than 6 hours indicates possible acute cholecystitis. Fever and chills suggest infected bile, with a possible empyema of the gallbladder. Jaundice is unusual except in coexisting obstruction of the common bile duct, either by stones or by extrinsic compression (Mirizzi syndrome). A palpable, somewhat tender mass is usual; the gallbladder at times may even be felt down in the pelvis.^{[1, 2, 3, 7, 9]}

Diagnostic criteria

The diagnosis of a mucocele should be considered in the following:

• Minimal acute inflammatory signs are present.
• A large, palpable, minimally tender gallbladder is found on clinical examination.
• Laboratory test results are normal or just within the upper limit of reference range values.
• Plain radiograph of the abdomen shows a soft-tissue–density, globular shadow in the subhepatic region.
• Ultrasonography of the RUQ shows evidence of minimal wall thickening, an impacted stone in the neck, or infundibulum of an enlarged gallbladder and clear content.
• Intraoperatively, the aspirate from the gallbladder is clear and watery or mucoid (white bile).
• The gallbladder on opening shows a white wall, clear and watery or mucoid content, a stone or stones impacted in the neck or cystic duct, a narrowed cystic duct, or a tumor and/or polyp causing obstruction of the neck of the gallbladder.

See Surgical Therapy.

See Pathophysiology.

The contraindications to surgical treatment of mucocele of the gallbladder would obviously include any associated medical conditions or illnesses that preclude surgery. No absolute contraindication exists.

Laboratory research has indicated that chemical ablation of the gallbladder mucosa might be an alternative in patients who are medically unfit, elderly, or critically ill. A combination of ethanol, sodium tetradecyl sulfate, and mucosal exfoliant has been successfully tried in rats.^{[1, 2, 3, 10]}