Cytopathology of nonlymphoreticular neoplasms metastatic to the central nervous system.

During a period of two years (1977 to 1978), 5,185 cerebrospinal fluid (CSF) specimens were examined in the Cytology Laboratory of Memorial Sloan-Kettering Cancer Center. Malignant cells were identified in 853 specimens. Of the positive specimens, 524 were obtained from 118 patients with nonlymphoreticular metastatic neoplasms. The most common tumors were mammary carcinoma (37%), pulmonary carcinoma (27%) and malignant melanoma (18%). The majority of epithelial tumors (77%) were adenocarcinomas. The interval between the primary diagnosis of malignancy and the time of first positive cytology varied significantly according to the type of neoplasm. The interval was approximately five times longer in patients with breast carcinoma and malignant melanoma (52 months) than in cases of lung carcinoma and bladder carcinoma (11 and 9 months, respectively). The prognosis, however, was invariably grave. Seventy-five percent of patients with follow-up died within 100 days of the first positive CSF. The tumor cells were often relatively small, with slight anisocytosis and pleomorphism as compared to their counterparts in other cytologic material. Cytology of the various neoplasms is presented, with attention to the morphologic changes during the follow-up period.