SDPS-43 OUTCOMES OF SUPRATENTORIAL FOCAL ENHANCING LESIONS CONCERNING FOR LEPTOMENINGEAL METASTASES

Leptomeningeal metastasis (LM) is an aggressive cancer complication with poor prognosis. Prompt diagnosis based on clinical findings, neuroaxis imaging, and cerebrospinal fluid (CSF) cytology- critical for appropriate, timely management. However, diagnosis is often challenging- as imaging lacks specificity and CSF cytology lacks sensitivity. Classic LM imaging findings include cerebellar folia, cranial nerve, and cauda equina enhancement. Of 103 patients with solid tumor brain metastasis referred to Neuro-Oncology at MD Anderson Cancer Center from 2016-2022 for evaluation of suspected LM on stereotactic radiosurgery (SRS) planning MRI, 15 had limited (≤5) nodular or linear focal enhancement in supratentorial sulci, without classic LM imaging. Upon initial workup, none had symptoms, neurologic deficits, or spine imaging consistent with LM; 10 underwent ≥1 lumbar puncture (median 1; range, 0-4) of which 2 (13%) had CSF cytology-confirmed disseminated LM. Majority were female (n=10); median age 60 years (range, 29-87). Most had lung (n=6) or breast (n=5) cancer. Five (33%) had history of craniotomy and resection of metastasis, with 1 resection cavity near supratentorial findings subsequently confirmed as LM. Both patients with confirmed LM received whole-brain radiation (WBRT)- instead of planned SRS- and intrathecal chemotherapy. One died 10.5m following diagnosis; the other continues therapy 11.6m later. In the remaining 13, the suspicious LM findings were determined to represent parenchymal/dural metastasis, treatment effect, or vascularity. Six were dispositioned to SRS, 3 to WBRT. One was ultimately diagnosed with LM (cytology-confirmed) 10m following WBRT. Nine subsequently received systemic therapy for intracranial and/or systemic disease. Median OS was 11 months (range, 4-37) from LM suspicion; 6 remain alive. In this small series, a minority of patients with supratentorial focal enhancing lesions without classic imaging findings were diagnosed with disseminated LM. Further study is needed to better stratify patients by LM risk and thus appropriateness of workup and intervention.