Primary plasmacytoma in the cerebellum: A case report and literature review

Background Most plasmacytomas arise in the bone marrow (intramedullary), as part of multiple myeloma (MM). In contrast, extramedullary plasmacytoma without MM is rare, and plasmacytoma primarily occurring in the brain parenchyma is extremely rare. Clinical behaviors of primary plasmacytoma in the brain have remained unclear. We report a case of primary plasmacytoma in the cerebellum and review the literature. Case Description The patient was a 33-year-old woman, displaying vertigo and peripheral facial nerve palsy. A tumor was identified in the subcortical white matter of the middle-upper cerebellum. Magnetic resonance imaging showed no specific findings for this lesion. Tumor was surgically resected because of aggressive tumor growth. Pathologic diagnosis of the tumor was plasmacytoma. The patient was treated with irradiation to the tumor bed after surgery. Although histology of the bone marrow showed a few atypical plasma cells (1%–2%), below the threshold of the diagnostic criterion for MM, we started chemotherapy to prevent occurrence of MM. Neither tumor recurrence nor development of MM was found for 16 months after surgery. Conclusions Histology is essential for diagnosis of primary plasmacytoma in the brain because of the lack of specific findings on neuroimaging. A finding of a few atypical plasma cells in the bone marrow might support the assumption that extramedullary plasmacytoma represents a harbinger of subsequent development of MM. In addition to appropriate therapies combining maximum tumor removal and radiotherapy to the brain, rigorous hematological management might have contributed to favorable outcomes.