Objective:

To describe radiologic, pathologic, and clinical findings in a patient diagnosed with an isolated intracranial plasmacytoma. 

Background:

Plasmacytomas are cancers arising from plasma cells.¹ They can occur as solitary lesions or in association with multiple myeloma. Rarely solitary plasmacytomas can occur intracranially. These tumors can be durably based or originate from bone, displacing adjacent structures with a radiographic appearance that can resemble meningioma.²

Design/Methods:

Case Report

Results:

A 68-year-old male presented with eight months of horizontal binocular diplopia and right eye proptosis. Computed tomography (CT) head identified a right sphenoid bone lesion with cortical erosion of the sphenoid and right frontal bones with associated mass effect and displacement of the right frontal lobe and extending into the orbit. Magnetic resonance imaging (MRI) of the brain further demonstrated effacement of the right frontal lobe and lateral rectus muscle. Differential diagnoses of this lesion included meningioma with bone infiltration, chondrosarcoma, and metastatic disease. The patient underwent a near-total resection. Pathology was consistent with plasmacytoma, kappa light chain restricted (M-spike 0.357 g/dL, IgG Kappa; Free light chains, mg/dL: Kappa: 5.97; Lambda 1.69; Kappa: Lambda ratio 3.53). [¹⁸F]Fluorodeoxyglucose positron emission tomography did not identify other lesions. Bone marrow biopsy myeloma minimal residual disease analysis by flow cytometry did not identify any monotypic plasma cells. The patient underwent radiation therapy (4005 cGy, 15 fractions) for intracranial residual disease. Diplopia and right eye proptosis resolved, and the patient continues radiographic and serologic surveillance.

Conclusions:

The differential diagnosis of an intraparenchymal intracranial lesion resulting in bone erosion is broad and includes plasmacytoma, meningioma, and chondrosarcoma. Intracranial plasmacytomas can occur in isolation without systemic multiple myeloma. Management of intracranial plasmacytoma involves maximal safe resection followed by radiation therapy for any residual disease. This approach can be curative, but long-term multidisciplinary surveillance is required as progression to multiple myeloma can occur.