Plasma cell granuloma is a lesional pattern of inflammatory pseudotumour, different from the "inflammatory myofibroblastic tumor" pattern.
Contents
It is linked to IgG4-related disease.
Pathology
Histologically, the lesions consisted of a proliferation of mature plasma cells and reticulo-endothelial cells supported by a stroma of granulation tissue, with varying degrees of myxoid change or collagenization. Angioinvasion within the lesion is observed in 50% of cases.
Immunohistochemical staining reveals the IgG-predominant polyclonal nature of the plasma cells, indicating a reactive inflammatory process rather than a neoplastic one.
Electron microscopy confirms the benign nature of the plasma cells with fibroblast and myofibroblast proliferation admixed with that of other inflammatory cells.