Isolated CNS involvement in Ewing's sarcoma.

Ewing's sarcoma, an uncommon malignant neoplasm of bone, represents about 10% of all the malignant primary bone tumors. The assumption that subclinical metastases are already present in patients with apparently localized tumor indicates the need for systemic therapy as an integral part of primary treatment. The usual sites of metastases are the lungs and skeletal system. Central nervous system (CNS) involvement is rare and is usually seen only in disseminated and fairly advanced disease. We report two patients in whom, after aggressive adjuvant chemotherapy, disease developed in the CNS without local recurrence. In one patient, meningeal involvement with malignant cells was identifiable in the cerebrospinal fluid; in the second patient, who presented with a space-occupying lesion, a diagnosis of arachnoid involvement was made histologically.