LMD-22. Clinicopathological spectrum of leptomeningeal metastases: A 3 year retrospective study

Abstract

Objectives Cytological examination of cerebrospinal fluid is a widely used cost effective, simple procedure and a reliable routine diagnostic test. CSF cytology helps in detection of inflammatory diseases of the CNS, diagnosis of subarachnoid haemorrhage and the identification of malignant cells in metastatic or rarely primary CNS malignancies.Leptomeningeal metastases (LM) is estimated to occur in 5% of all patients with cancer. It has a higher propensity to occur in solid tumours compared to haematological malignancies.In view of poor prognosis, early diagnosis may aid in appropriate tumour staging and aggressive therapeutic intervention. Methods All the samples of CSF received in the Department of Laboratory for cytological examination and reported as ‘positive for malignant cells’ during the year January 2018 to December 2020were included in the study. All the cases were routinely evaluated on Neubauer’s chamber, direct smear and a cytospin preparation stained using MGG stain. The clinical records and any further ancillary testing performed were retrospectively analysed. Results 87cases with LM were identified over 3 year duration. Mean age of presentation was 43 years. Metastatic solid malignancies (56%) had a higher incidence of leptomeningeal metastases compared to haematolymphoid malignancies (40%) and CNS medulloblastomas(2%). Most common solid tumour with involvement of CSF was adenocarcinoma lung (51%) followed by breast carcinoma (37%). Of all the cases of adenocarcinoma lung with LM, EGFR mutant NSCLC were 40% while 8% showed ALK gene rearrangement. Amongst the haematological malignancies, acute leukaemia’s constituted 67% of cases while systemic NHLs were 34%. Most of the cases (97%) presented with neurological symptoms during the course of treatment while 3 cases (3%) showed LM at the time of first presentation. Conclusions With appropriate clinicoradiological correlation, CSF cytology remains the gold standard for identification of malignant cells in cases with already known primary tumour (leptomeningeal dissemination of the disease). In this study, clinical features of both solid and haematolymphoid malignancies were evaluated. The group of solid malignancies included adenocarcinomas lung, breast, gastrointestinal tract and renal cell carcinoma. With the availability of EGFR TKIs and ALK inhibitors, overall survival of the patients may be prolonged with therapeutic interventions despite limited CSF and CNS penetration of these drugs.