Neurofibroma of the Gallbladder Not Associated with Neurofibromatosis

An 82-year-old woman had visited her local clinic with a history of abdominal discomfort and dyspepsia related to meals over a period of several months. Esophagogastroduodenoscopy revealed a superficial spreading tumor that, on biopsy, was proven to be an adenocarcinoma, and colonoscopy revealed an ascending mass that was found to be an adenocarcinoma on biopsy, so the patient was referred to our hospital. Abdominal computed tomography revealed a mass in the ascending colon with regional lymph node swelling and a gallbladder stone measuring 1.5 cm in diameter. The patient underwent laparoscopy-assisted distal gastrectomy with cholecystectomy and right colectomy with regional lymph node dissection, resulting in a diagnosis of poorly differentiated adenocarcinoma invading the gastric submucosal layer and moderately differentiated tubular adenocarcinoma invading the colonic serosa with lymph node metastasis. Macroscopic examination of the gallbladder revealed a well-circumscribed, solid tumor measuring 0.3 x 0.3 cm with a firm consistency in the neck portion associated with lithiasis. Microscopic examination of the gallbladder tumor revealed infiltration of spindle-shaped neoplastic cells that were arranged in a fasciculated and woven pattern in abundant intersecting bundles. Immunohistochemical analyses were positive for S-100 protein and neurofilament. Although neurofibromas commonly occur in the superficial skin or subcutaneous region, isolated neurofibroma of the gallbladder is quite rare. To the best of our knowledge, this is only the 11th case of a neurofibroma of the gallbladder to be reported in English literature. In the present case, as in most previously reported cases, the tumor was found incidentally in the resected gallbladder following cholecystectomy for cholecystolithiasis.