Congenital granular cell tumor with systemic involvement. Immunohistochemical and ultrastructural study.

We present an autopsy case of a 29-week-old male fetus with a very unusual set of congenital granular cell tumors, including gingival epulis and granular cell lesions of the kidneys, lung, heart, esophagus, small and large intestine, thyroid, adrenals, spleen, urinary bladder, testis, pituitary, and leptomeninges. The granular cells were distributed mainly through the stroma of the organs, but they also involved the epithelial lining of the seminiferous and renal tubules. Ultrastructurally, the gingival, pulmonary, and renal tumors were basically the same in appearance as membrane-bound heterogeneous bodies. Immunohistochemical studies were negative for S100 protein, lysozyme, alpha 1-antitrypsin, cytokeratin, and vimentin in the gingival mass as well as in other systemic lesions. The immunohistochemical reaction pattern of the granular cells in our case was more like the cells of the congenital granular cell epulis rather than adult granular cell tumor because of its negative reaction to S100 protein. However, the involvement pattern was that of the adult form of granular cell tumor. Several developmentally different cells, such as renal tubular epithelial cells, seminiferous tubular cells, gingival stromal cells, and parenchymal cells of many organs, were involved in this granular cell process. The myofibroblastlike cells seen in the region of segmental dysplasia of the kidney showed the same cytoplasmic material as in typical granular cells. Based on these findings, it is suggested that a histogenesis of multiple cell origin of the granular cell tumor could be strongly supported.