Two cases of granular cell tumor of the tongue.

Granular cell tumor is a rare lesion of unknown origin. The oral cavity, particularly the tongue, appears to be the most common site of the lesion. We experienced two cases of granular cell tumor in the tongue.Case 1: A 12-year-old female visited our clinic complaining of a mass in the left lateral margin of the tongue. The lesion occurred about 4 years ago and had not caused any pain and discomfort. It was excised under local anesthesia on July 27, 1984.Light microscopically, the lesion was composed of a diffuse proliferation of large cells with eosinophilic granules. They contained diastase-resistant PAS-positive granules. Electron microscopical examination showed the basement membrane surrounding each tumor cell and, in cytoplasm many lysosome-like vacuoles contained electron dense particles or myelin figures. No relapse of the tumor was seen 18 months after the operation.Case 2: A 39-year-old female visited our clinic, complaining of a mass in median dorsum of the tongue. The tumor was resected under local anesthesia on October 6, 1985. The patient was relieved of her complaint without any recurrence at 6 months after the operation. Under light microscopy, the tumor showed a marked proliferation of the tumor cells with abundant eosinophilic granular cytoplasm. In the covering epithelium, pseudoepitheliomatous hyperplasia was found. Under electron microscopy, the tumor cells were surrounded by the basement membrane. In cytoplasm, there were numberous granules with a limiting membrane.Our investigation by light and electron microscopic examination showed the basement membrane surrounding each tumor cell and in cytoplasm, and many lysosome-like vacuoles containing electron dense particles or myelin figures. But myofibrils were not found. These findings suggest that the histogenesis of the granular cell tumor is a neurogenic origin.