PAT7 Multicentric granular cell tumor with unusual mammary, gastric and pancreatic involvement: A case presentation.

PAT7 MULTICENTRIC GRANULAR CELL TUMOR WITH UNUSUAL MAMMARY, GASTRIC AND PANCREATIC INVOLVEMENT: A CASE PRESENTATION. Zohreh Zaki, MD, Nizar Habal, MD, and Cristian Robiou, MD. East Carolina University, Brody School of Medicine, Pitt County Memorial Hospital, Greenville, NC.

Granular cell tumor (GCT) is a usually benign neoplasm of controversial Schwann cell origin. It is commonly solitary but can be multicentric. Skin, subcutaneous tissue and oral mucosa are common sites but GCT has been described in many organs. Only one previous case of pancreatic GCT has been reported in the English literature. We present a 55-year-old female with history of sarcoidosis and hypertension who presented with a 4 month history of an unexplained 35 pounds weight loss and a mass in right breast. On mammography, a benign appearing well-defined 1.2 cm nodule was identified. This mass was excised. Grossly, the tumor was well defined with solid tan surfaces. Microscopically, a diagnosis of benign GCT was made. During work up for the unexplained weight loss, an abdominal CT scan showed a mass in the body of pancreas. She underwent a distal pancreatectomy and splenectomy. During surgery, another mass was found in the stomach wall. This mass was also resected. Perigastric and periportal lymph node biopsie s as well as omental biopsy were performed. Gross examination of the pancreas showed a well-defined 1.8 cm mass with solid homogenous white-tan surfaces. The pancreatic margins were unremarkable. Spleen was unremarkable. The gastric mass measured 1.5 cm with the same features as the pancreatic mass and was covered by intact mucosa and serosa. Microscopic examination of both masses showed a neoplasm composed of nests and cords of round to oval cells with abundant pink granular cytoplasm embedded in a fibrous stroma. There were foci of nuclear pleomorphism with occasional prominent nucleoli. No vesicular nuclei, mitotic activity, necrosis or vascular invasion was seen. At the periphery of the pancreatic mass nerve bundles surrounded by tumor cells were seen. Frequent PAS positive eosinophilic droplets as well as diffuse cytoplasmic reactivity for S100 protein were noted. Multiple sarcoid-type granulomas were found within both tumors, pancreatic tissue, gastric mucosa and lymph nodes. DNA analysis of the pancrea tic mass revealed a 42% aneuploid population and DNA index of 1.3. Based on the histologic findings a diagnosis of atypical GCT was rendered. The patient has had an unremarkable 3-month post-surgery follow-up with no further treatment. Atypical and malignant GCTs are uncommon. Reliable histologic criteria for malignancy has not been established since tumors with benign histologic appearance can metastasize. In evaluating malignant potential the adverse prognostic factors include vesicular nuclei, large nucleoli, spindle tumor cells, increased mitotic activity, necrosis, older patients age, tumor size, local recurrence and metastasis.