Solitary Plasmacytoma with Amyloid - An Unusual Dural-Based Lesion.

Solitary plasmacytoma of the dura without systemic involvement are extremely rare lesions, with <15 cases reported in the literature. Among these, ours is the second case to show the presence of amyloid. Fifty-year-old male had presented with headache, sudden onset right-sided weakness, and vomiting. Magnetic resonance imaging revealed an extra-axial mass in the left fronto-parietal region measuring 10 cm × 8.7 cm × 3.9 cm, suggestive of meningioma. The left fronto-parietal craniotomy was performed and multiple tissue bits aggregating to 10 cm × 8.5 cm × 2 cm along with thinned out membrane-like bit of calvarium was sent for pathologic examination. H and E stained sections showed sheets of plasmacytoid cells along with amyloid, which showed apple-green birefringence on Congo red staining. On immunohistochemistry, tumor cells were positive for CD38, CD138, showed kappa light chain restriction and were negative for CD45, CD34. Hence, it was diagnosed as a plasma cell neoplasm. Further work-up with whole-body positron-emission tomography scan revealed no systemic involvement. Dural-based lesions can mimic meningioma radiographically as well as intraoperatively. Histopathological examination unveils the diagnosis, to guide appropriate therapeutic regimens.