A 52 year old female presented with an asymptomatic lesion of the left mandible. The lesion was excised and underwent gross and microscopic examination.
The specimen was examined on two H&E stained slides after decalcification procedure and revealed soft tissue and bone with diffuse sheets of plasmacytoid cells with minimal fibrous stoma and few small capillaries. The plasmacytoid cells showed eccentrically placed nuclei and peripheral chromatin beading, resembling plasma cells. The bony tissue showed focal osteomyelitis. Mitotic figures nor prominent nuclear atypia were not seen. Immunohistochemical staining was performed and showed the cells to be positive for CD138, CD117, and EMA. Testing via ISH for kappa and lambda showed a polyclonal population of plasma cells.
Plasma Cell Granuloma, or Inflammatory Pseudotumor
Plasma cell granuloma, can also be known as an inflammatory pseudotumor. It is a rare benign process considered to be the result of an inflammatory condition. Plasma cell granulomas are extremely rare in the oral cavity. The affect both males and females equally and have no definite age of presentation. Other names for this process are: Inflammatory myofibroblastic tumor, Inflammatory pseudotumor, Inflammatory myofibrohistiocytic proliferation, and Xanthomatous pseudotumor.
The exact incidence of plasma cell granuloma is unknown. The lesion’s pathogenesis, biological behavior, and appropriate treatments are unclear, and little is known about the prognosis. It may arise due to periodontitis, periradicular inflammation due to the presence of a foreign body or may be due to an idiopathic antigenic cue. The most commonly considered treatment for plasma cell granuloma is a complete resection; however, in some cases, total surgical excision is not possible.
The immunohistochemistry determines the clonality of the lesion, where, in a reactive lesion, the kappa to lambda light chain ratio is 2:1, and in the case of malignancy the ratio may be greater than 10:1 or 1:10.
Cases such as these reinforce the existence of plasma cell granuloma in the oral cavity and the need for submitting all the excised tissue for microscopic examination, irrespective of the clinical features and clinical diagnosis.
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Karthikeyan BV, Pradeep AR. Plasma cell granuloma of gingiva. Indian J Dent Res. 2004;15:114–6.