Papers of the Week

Primary central nervous system lymphoma (PCNSL) occurs frequently in a deep intraparenchymal location. It rarely occurs in the meninges, and bone invasion is uncommon. A 12-year-old boy was admitted to our hospital with a history of headache and seizures. Magnetic resonance imaging showed a 4 cm-sized dural-based mass with osteolytic bone change. Craniotomy and tumor removal were performed. Operative findings showed a dural-based hard tumor including necrosis and hemorrhage, and the skull was focally destroyed by tumor cells. The tumor was completely removed. Pathologically, large atypical cells with pleomorphic nuclei and frequent mitoses were found. The tumor cells were immune-positive for CD30, epithelial cell antigen, and anaplastic lymphoma kinase (ALK). The final diagnosis was ALK-positive anaplastic large cell lymphoma (ALCL). There was no evidence of systemic cancer. The boy underwent chemotherapy following the Non-Hodgkin Lymphoma-Berlin-Frankfurt-Münster protocol. There was no recurrence after a 16-month chemotherapy-off period. ALCL is not a common type of PCNSL, and CNS ALCL frequently involves the dura and meninges compared to PCNSL in general. However, osteolytic bone lesions are rarely seen in ALCL. This case thus represents a rare case of dural based ALCL with bone invasion.