Extraosseous (extramedullary) plasmacytoma of the adrenal gland.

Plasmacytomas are clonal proliferations of atypical plasma cells that manifest a localized osseous or extraosseous growth pattern. Although many represent solitary lesions of bone, fewer arise in extraosseous (extramedullary) tissues. We report a case of a primary extraosseous plasmacytoma of the adrenal gland. Magnetic resonance imaging (MRI) with contrast revealed a 3.5-cm, right adrenal mass with heterogeneous enhancement. Although the mass was small and nonfunctioning, concern for malignancy based on MRI findings prompted laparoscopic resection. Histologic and immunohistochemical findings were consistent with a plasmacytoma. This is the third reported case, to our knowledge, of a primary plasmacytoma of the adrenal gland. The present case is unique in that a contrast MRI was performed, which showed heterogeneous enhancement of the mass, providing further evidence beyond heterogeneous hyperintensity on T2-weighted images for a possible malignant process. Another unique feature is that a biopsy specimen of the lesion was taken, although it was nondiagnostic.