A 72-year-old woman with right frontal extra-axial mass

Area of Science:

• Neuropathology
• Oncology
• Cell Biology

Background:

• Meningiomas are common primary brain tumors arising from meningeal cells.
• Lymphoplasmacyte-rich meningiomas are a recognized subtype, characterized by a significant presence of lymphocytes and plasma cells.
• Plasma cell inclusions are typically associated with reactive inflammatory conditions or plasma cell neoplasms.

Observation:

• A 72-year-old woman presented with memory disturbance and a right frontal extra-axial mass on MRI.
• Histopathological examination revealed a benign meningioma with numerous plasma cells containing lamellar inclusions and bipyramidal crystals.
• Immunohistochemistry confirmed CD79a and PGM1 positivity in crystal-containing cells, with polyclonal kappa light chain expression.

Findings:

• The study identified a novel finding of crystalline inclusions within plasma cells in a lymphoplasmacyte-rich meningioma.
• Electron microscopy characterized these inclusions as needle or rectangular shaped crystals within the plasma cells.
• These crystalline deposits represent a previously unreported feature in meningioma pathology.

Implications:

• This case expands the spectrum of histological variations observed in meningiomas.
• The presence of crystalline inclusions may warrant further investigation into their composition and potential clinical significance.
• This finding contributes to the understanding of plasma cell morphology and potential intracellular inclusions in neoplastic and non-neoplastic central nervous system lesions.