Malignant granular cell tumor of the esophagus. A case report with light and electron microscopic, histochemical, and immunohistochemical study

Malignant granular cell tumor of the esophagus found in a 70-year-old female was reported. Microscopically, the tumor showed a variety of the histology from compact proliferation of polygonal granular cells in pseudo-epitheliomatous pattern to plexiform proliferation of elongated granular and fibroblastic cells in neurofibromatous pattern, and the tumor cells frequently contained eosinophilic globules in the cytoplasm. Histochemically, argyrophilic neurofibrils in the stroma and argyrophilic cytoplasmic processes or grains were seen. Immunohistochemically, the tumor cells showed positive reaction with S-100 protein (S-100), but all reactions with myoglobin (MG), desmin (DM), fibronectin (FN), creatinine phosphokinase-mm (CPK), factor 8th-related antigen (F8RA), alpha-1-antitrypsin (A1AT), alpha-1-antichymotrypsin (A1ACT), keratin (KN), and carcinoembryonic antigen (CEA) were negative. Electron microscopy revealed that the tumor cells had typical lysosomal granules filled with proteinaceous electron dense materials and fine membrane-bound particles sized 15 to 45 nm resembling virus or neurosecretory granule.