Giant Cell Tumor of Soft Tissue Involving the Common Hepatic Duct: A Case Report and Review of the Literature.

Giant cell tumor of soft tissue is a low-malignant behavior neoplasm, with histopathological features and immunophenotype similar to its bone counterpart. Primary giant cell tumor of soft tissue in the biliary tract is an exceedingly rare entity. Here, we describe the first patient of giant cell tumor of soft tissue involving the common hepatic duct in a 66-year-old man who developed a biliary obstruction. Imaging revealed an ill-defined 34 × 21 mm intraluminal mass at the liver hilum, initially suggestive of a Klatskin tumor. A right hepatectomy with excision of the common hepatic duct and gallbladder was performed, followed by a Roux-en-Y cholangiojejunostomy. Histological examination revealed that the entire tumor was not associated with any other form of carcinoma but was morphologically similar to giant cell tumors of soft tissue. The lesion consisted of 2 distinct cell populations: mononuclear cells and multinucleated osteoclast-like giant cells. The mononuclear cells displayed no atypical features, and their nuclear characteristics were similar to those observed in the multinucleated giant cells. Tumor cells were negative for keratin AE1/AE3, keratin 7, keratin 19, and keratin 20, but positive for CD68. The patient remained well, without local recurrence or metastasis during 6 years of follow-up. The present tumor highlights the rarity of the location, and the diagnostic challenges encountered prior to surgery.