Durable remission with Bruton's tyrosine kinase inhibitor therapy in a patient with leptomeningeal disease secondary to relapsed mantle cell lymphoma.

Mantle cell lymphoma (MCL) is an incurable B cell non-Hodgkin's lymphoma with a variable clinical course. Central nervous system (CNS) involvement is a rare and dreaded complication in MCL. We report a case of leptomeningeal relapse of MCL that was successfully treated with a single-agent Bruton's tyrosine kinase inhibitor. A man in his 50s with MCL was treated with six cycles of bendamustine-rituximab, achieving a complete remission (CR) and was subsequently placed on rituximab maintenance for 2 years. Four years later, he was hospitalised with symptoms of organic brain syndrome. Brain MRI and cerebrospinal fluid analysis confirmed CNS relapse of MCL. He was treated with dexamethasone, ibrutinib 560 mg/day and intrathecal cytarabine with improvement in neurological symptoms, and a follow-up MRI showed CR. The patient was later switched to acalabrutinib due to intolerance to ibrutinib. The patient is tolerating this regimen well, remaining in CR 3 years later.