Occult hepatic sinusoid tumor of infancy simulating neuroblastoma.

Two infants with hepatosplenomegaly and an occult tumor of hepatic sinusoids are reported. Although secretion of biogenic amines of neuroblastoma was not elevated, infrequent neurosecretory granules were observed by electron microscopy in the cytoplasmic processes of the tumor cells. The infants responded to vincristine and prednisone therapy and are tumor free 8 and 2 years later, respectively. The clinical, radiographic, biochemical, and microscopic findings of these cases are presented. The distinction from other infantile hepatic sinusoid small round cell tumors is based on the light and electron microscopic findings. This neuroepithelial tumor is either an unusual form of neuroblastoma or a neoplasm of APUD cell origin. If chemotherapy is utilized, it should be selective and limited.