Leptomeningeal carcinomatosis in small cell carcinoma of the lung

Among 137 patients with small cell carcinoma of the lung (SCCL) treated on two consecutive protocols, leptomeningeal metastases were documented in 12 patients (9%), 10 antemortem by cerebrospinal fluid (CSF) cytology, one by myelogram, and one only at necropsy. Signs and symptoms included confusion in seven, limb weakness in six, paresthesias in three, headache in two, urinary incontinence in two, and nausea and vomiting, diplopia and neck pain in one patient each. Nine of the 12 patients had evidence of other metastases while three patients relapsed first in the CSF and one had disease only in the leptomeninges. Treatment for this complication including irradiation, intrathecal chemotherapy, or systemic chemotherapy was generally ineffective with a median duration of survival of 50 days (range 5 to 130) after diagnosis of leptomeningeal. Necropsies showed thick tumor deposits along cord, distal nerve roots, cauda equina, and in Virchow--Robbins spaces with deep invasion into adjacent neural substance in six of the seven. Leptomeningeal involvement appears to have become manifest as median survival has increased. CSF cytology should therefore be examined in patients who develop unusual neurological findings during the course of this disease and methods of prevention may need to be considered in future studies.