Subcutaneous gallstone: a case report

Cholecystocutaneous fistula (CCF) is a rare presentation of gallbladder pathology, wherein an abnormal connection forms between the gallbladder and the skin, often with an associated abscess.^1–3

Case report

A comorbid, frail 93-year-old woman presented with a 6-week history of a red lump in her right upper quadrant. She had no previously reported cholecystitis, biliary symptoms or right upper quadrant incisions.

Initially presumed to be a simple skin infection, she was treated with oral antibiotics. However, due to minimal improvement, she was referred for an ultrasound; this found an area of increased vascularity around mineralisation deep to the dermis, with an unclear relationship to the peritoneum. The gallbladder and distal common bile duct were not well visualised, and there was suspicion for a porcelain gallbladder.

Her liver function tests (LFTs) were normal, except for a bilirubin of 32—this appeared to be her baseline level. She previously had mildly raised LFTs—6 months earlier—thought secondary to fluid overload, which had improved with treatment.

Her computed tomography (CT) scan showed findings consistent with a subcutaneous calcified gallbladder containing a 1cm calculus, with a cystic duct traversing the anterior abdominal wall which could be traced back to the common bile duct; it was postulated this was secondary to previous cholecystitis with associated cholecystocutaneous fistulation. A previous CT scan 18 months prior had shown an intra-abdominal contracted gallbladder with wall calcification and a calculus.

View Figure 1–3.

After discussion with a hepatobiliary surgeon, the decision was made to treat with a simple incision and drainage procedure under local anaesthetic and sedation, given her age and comorbidities. A 4cm gallstone was removed, with minimal pus, no bile, no calcifications or obvious gallbladder wall tissue, and no appreciable fistula or duct.

After washing out with saline, an Aquacel® wick was placed and was removed after 24 hours. No bile was ever noted coming from the wound. She received a further 24 hours of intravenous antibiotics and was discharged home to complete a 5-day oral antibiotic course.

Discussion

This was an unusual presentation of CCF—an already rare presentation with fewer than 25 cases reported in the last 50 years, with a significant reduction in cases since the increased availability of antibiotics and cholecystectomies.^1–3 Most presentations tend to be associated with recurrent episodes of cholecystitis or chronic biliary tract disease, or complications of cholecystostomies, though there are also suggestions that steroids, trauma, typhoid, and bacterial dissemination may predispose towards CCF formation.^2–4 CCF tends to present in women older than 50, like our patient, though her lack of previous abdominal pain was very unusual, despite her prior CT scan suggesting biliary pathology.^3,4 Although her stone was in the subcutaneous tissue, no fistula was identified—an exceedingly rare occurrence.

Due to its rarity, there is not a clear consensus on the most appropriate management of CCF.^1,2 Generally, immediate drainage of the abscess and treatment with antibiotics seems to be standard practice, though often there is either an immediate open cholecystectomy and excision of fistula tract or an interval laparoscopic cholecystectomy; in the case of our comorbid patient, this definitive treatment was not indicated.^1,2

Conclusion

This case highlights the importance of considering a cholecystocutaneous fistula in right upper quadrant abscesses, with or without previous biliary pathology, and therefore ensuring appropriate imaging prior to operative management.