RESUMO
BACKGROUND: Primary central nervous system (CNS) anaplastic large cell lymphoma (ALCL) is an uncommon type of brain tumor, usually treated with a regimen that includes high-dose methotrexate (MTX). Only a few cases of primary CNS anaplastic lymphoma kinase (ALK)-positive ALCL have been reported so far, with no reported cases of a small cell variant. CASE DESCRIPTION: A 26-year-old man presenting with headache and visual field impairment was found to have a supratentorial mass mimicking meningioma. Craniotomy was performed for tumor resection, and postoperative histologic examination revealed atypical cells that were nonenlarged lymphocytes with irregularly shaped and enlarged nuclei; these cells were cluster of differentiation 30 and ALK-positive, leading to the diagnosis of a small cell variant of ALK-positive ALCL. In this case, the tumor exhibited an aggressive behavior with MTX resistance with metastases in the pelvis but responded well to cytarabine and etoposide (CYVE). CONCLUSIONS: In general, CNS ALK-positive ALCL responds well to MTX, but small cell variants show aggressive behavior and may be resistant to MTX. For small cell variants of ALCL that are resistant to MTX therapy, as in this case, CYVE therapy may be an effective treatment.