Granular cell tumor of the intrapancreatic common bile duct: one case report and review of the literature.

A granular cell tumor (GCT) in a 39-year-old white man is reported. It was localized in the intrapancreatic part of the common bile duct and caused obstruction of the bile downflow. The patient underwent radical surgical procedures because a malignant tumor was clinically suspected. Macroscopically, the tumor appeared as a duct stricture caused by diffuse infiltration of neoplastic cells in the walls. In the cytoplasm smaller and larger PAS-positive granules were present and constantly reactive to S-100 and NSE antibodies. Ultrastructurally, cytoplasmic granules appeared as membrane-bound vacuoles of variable size and shape containing debris, disrupted mitochondria, and myelin figures. No basal lamina around cell cytoplasm was observed. GCTs are relatively uncommon soft tissue tumors usually presenting in the skin and subcutaneous tissues or tongue. The prognosis in any location is quite good, but very rare malignant GCTs (1-2%) are documented. Complete excision reduces the risk of recurrence. Accurate operative diagnosis seems to be critical when the tumors are located in the intrapancreatic common bile duct as in this reported case. Gastro-pancreatico-duodenectomy is too radical a procedure for such a benign lesion and additional assessments and investigations are recommanded before such an extensive radical surgery.