Hepatobiliary and Pancreatic: Traumatic bile duct neuroma

Abstract

A man, aged 76, was recovering after surgery for a perforated rectosigmoid cancer. His past history included a cholecystectomy for gallstones, 17 years previously. A computed tomography scan of the abdomen showed a small enhancing nodule in the mid-bile duct. Liver function tests were normal but the serum carbohydrate antigen, 19.9 (CA19.9) level was elevated at 302 U/mL (reference <37 U/mL). A magnetic resonance cholangiogram showed eccentric wall thickening of the mid-bile duct (arrow) consistent with a bile duct neoplasm (Figure 1). At surgery, he had a hard mass, 1 cm in diameter, in the mid-bile duct and had a segmental resection with a Roux-en-Y hepaticojejunostomy. Histological examination revealed hyperplastic and disorganised nerve fibers surrounded by fibrous connective tissue (H&E x200, Figure 2). Immunohistochemical stains were positive for S100 (inset Figure 2). The diagnosis was that of a post-operative (traumatic) neuroma of the bile duct. A neuroma or traumatic neuroma is an exuberant but non-neoplastic proliferation of a nerve that occurs after injury or surgery. After biliary surgery, neuromas can occur in the cystic duct stump but neuromas involving the bile duct are rare. Macroscopically, they are small white-gray nodules that develop at the proximal end of the injured or transected nerve. Histologically, there is a haphazard proliferation of nerve tissue that includes axons, Schwann cells and fibroblasts surrounded by a fibrous capsule. Cystic duct neuromas may be a cause of biliary-type pain after cholecystectomy and, historically, one surgical option was shortening of the cystic duct stump. The results of this procedure remains unclear. More recently, an interesting case report described three patients with pain after cholecystectomy whose symptoms were aggravated by pushing on cystic duct clips with a needle guided by endoscopic ultrasound. Symptoms improved after an injection of local anesthetic and steroid into the region and 2 of 3 patients had resection of the cystic duct stump (Am J Gastroenterol, 2005; 100: 491). Whether neuromas of the bile duct cause pain remains unclear but these nodules can result in extra-hepatic obstruction. In the latter setting, the differential diagnosis can include post-operative strictures, retained stones, benign tumors and bile duct cancer. A pre-operative diagnosis of bile duct neuroma is likely to be difficult and most patients have been treated by surgery, usually with an hepaticojejunostomy. Contributed by