Cytopathology of neoplastic meningitis: A series of 66 cases from a tertiary care center

BACKGROUND: Neoplastic meningitis (NM) is a condition characterized by leptomeningeal involvement by metastatic carcinoma. Detection of exfoliated malignant cells in cerebrospinal fluid (CSF) due to meningeal metastasis is frequently associated with diverse neurologic presentations. MATERIALS AND METHODS: In this retrospective study of all cases of NM diagnosed in CSF samples over a 20-year period at a tertiary care referral center, the cytomorphologic features were reviewed. RESULTS: Sixty six cases of NM were identified of which 36 already had an established diagnosis of malignancy while in 30 patients, there was no previously known tumor. The most common known primary in the former group was breast followed by ovary. Single cell pattern, cellular cannibalism, moderate cytoplasm and rounded nuclei were seen in breast and lung tumors. Papillary architecture and cytoplasmic vacuolation were seen in the ovarian primaries. Melanin pigment was seen in malignant melanoma. CONCLUSION: CSF cytology is an important tool for diagnosis of NM. Cytomorphologic features helped in diagnosis and for prediction of the primary site. Correct identification of this condition is important as it has therapeutic and prognostic implications.