Histological and fine structural studies on pigmented neuroectodermal tumor of infancy

Pigmented neuroectodermal tumor of infancy originating from the anterior maxilla in a two-month-old male has been studied by light and electron microscopy. The tumor is characterized histologically by two types of neoplastic cells embedded in considerable amounts of fibrous stromal tissue. The first type of cell is cuboidal to columnar in shape with an epithelial appearance having abundant cytoplasm; either scanty or a heavy accumulation of melanin pigment is observed in the cytoplasm. These cells are aligned along the cleft-like space or arranged in small ductal structures. Electron microscopy shows the characteristic features of melanocytic cells having a varying degree of asynchronous maturation of melanosomes. The second type of cells is small and round in shape and has a hyperchromatic nucleus and scanty cytoplasm, resembling neuroblastic cells or lymphocytes. Electron microscopy reveals cytoplasmic processes resembling immature neuritis which protrude into the intracellular space; a small number of secretory granules having a central core surrounded by a single limiting membrane are observed in the cytoplasm and cytoplasmic processes.