Clinical and histopathological studies of granular cell tumor of the tongue]

We studied the clinical and histopathological characteristics of granular cell tumor (GCT) of the tongue in 5 cases (2 males and 3 females) over a period of 25 years. The patients ranged in age from 8 to 44 years old. In 4 cases, the site of origin in the tongue was the anterior two thirds of the lateral border (UICC). In the remaining case, the tumor originated on the dorsal surface of the tongue (UICC). The tumor was 3-10 mm long and had an average diameter of 6mm. The lesions were painless. The cellular granules in all the tumors reacted positively to PAS regent and S-100 protein using immunohistological methods. Other immunohistological staining using anti-actin antibody showed cellular granules beneath the epithelium. In one case, these findings were especially marked in the portion that exhibited pseudo-epitheliomatous hyperplasia. There was a mixture of both positive and negative cells in the deep layer of the epithelium. Not all tumor cells stained with anti-desmin antibody, however, there appeared to be a direct transitions from stained striated muscle fibers to the tumor cells. Staining with anti-vimentin antibody was positive at the boundaries between cells and the positive granules in cells appeared in the dots. Two of the five, tumors were unencapsulated, and the other 3 were partially encapsulated. The constituent fibers of the capsule consisted of collagen fibers alone. Thus, the former 2 cases should be regarded as proliferative in nature, and the latter 3 as benign. These tumor cells were potentially very active beneath the epithelium. From the results of our immunohistological stainings, we concluded that myoepithelial cells might also be the source of GCT cells, although GCT cells have generally been reported to originate from muscle and nerve cells. We maintain that care must be taken when removing GCTs because there may be proliferative growth along the epithelium.