Efficacy of thiotepa-conditioned autologous stem-cell transplantation as consolidation therapy for primary leptomeningeal malignant lymphoma: a case report and review of literature.

Primary leptomeningeal malignant lymphoma (PLML) is a rare subtype of primary central nervous system lymphoma (PCNSL). Treatment is often based on PCNSL, but currently there is no established treatment strategy due to its rarity. We report a case of a 46-year-old male diagnosed with PLML through cerebrospinal fluid cytology and flow cytometry, presenting with multiple cranial nerve palsies and L5 radiculopathy. The patient achieved complete remission (CR) with R-MPV (rituximab, methotrexate, procarbazine, and vincristine) combined with intrathecal chemotherapy (methotrexate, cytarabine, and prednisolone). This was followed by autologous stem-cell transplantation (ASCT) using a thiotepa-based conditioning regimen, resulting in sustained CR. A literature review on the use of ASCT for PLML revealed three reported cases, including ours, all achieving CR with ASCT and minimal adverse events. These findings suggest that ASCT can be a promising consolidation therapy for PLML. Further studies are needed to establish standardized treatment protocols for this rare condition.