The surgical plane between the VIIth nerve and acoustic tumor is often elusive. This histological relationship was reviewed in three patients who underwent VII-VII neuroanastomosis at tumor removal disclosing an inseparable surgical plane in two. In the third patient, tissue sections did not accurately show the relationship. In all three, surgical planes were not apparent at tumor removal. Another patient had a second, isolated tumor in the same VIIIth nerve proximally at the brain stem root entry zone. This was seen only on permanent section. In considering "total" tumor removal by microsurgical standards, these histological findings should be kept in mind. We advocate removal of the entire VIIIth nerve to the brain stem root entry zone along with smaller tumors.

A 20-year-old white male was initially suspected clinically and pathologically of having an acute lymphoblastic leukemic process because of fatigue, severe anemia, thrombocytopenia, a leuko-erythroblastic peripheral blood picture, and a diffusely infiltrated bone marrow. Subsequent review of the bone marrow material indicated cytologic features consistent with either an embryonal, undifferentiated small cell mesenchymal malignancy or reticulo-endothelial malignancy. Ultimately, the electron microscopic (EM) study of the tumor proved to be diagnostic of rhabdomyosarcoma. An extensive search for a primary site of rhabdomyosarcoma did not show any lesion, although the genitourinary region was clinically suspected. The clinical course was a rapidly downhill one with extensive bone and CNS involvement. The patient died 5 months later. An autopsy permit was not obtained. This case emphasizes the occasional tendency of rhabdomyosarcoma to masquerade as a hematopoietic malignancy at the time of presentation and the usefulness of EM study in confirming a diagnosis.