for further confirmation. Common results associated with kappa/lambda in-situ hybridization studies of PCGs are an abundant population of CD138 positive polyclonal plasma cells. If instead, results show monoclonality of plasma cells it is indicative of plasmacytoma. Determining Plasma Cell Clonality The clonality of plasma cells is most accurately determined by two different methods. One method is flow cytometry and the other is kappa/lambda in-situ hybridization and/or immunohistochemical staining (IHC). To obtain the most precise results of clonality it is recommended that both methods be used. Flow cytometry is generally carried out with plasma cell granulomas to obtain the ratio of kappa light chains to lambda light chains. Immunohistochemical staining of plasma cell granulomas is an important diagnostic method to show PCG lesions are also an entity within the IgG4-related diseases. IHC staining is especially helpful because it allows for the assessment of the quantitative number of IgG4 positive plasma cells. Immunohistochemical staining will also provide the overall ratio of IgG4 secreting plasma cells to the total number of IgG secreting plasma cells within a given mass. Plasma cell granulomas have been characterized showing a ratio of IgG4:IgG of greater than 40 percent. A ratio above 40 percent indicates abnormal elevated levels of IgG4 positive plasma cells. Even though IgG levels can be measured in serum, histopathological analysis has been concluded to be the most accurate characterization method of PCG lesions. Using serum IgG4 levels can be a misleading diagnostic, considering that up to 40 percent of patients diagnosed with plasma cell granuloma have IgG4 serum levels within normal reference ranges. Treatment for PCG The typical treatment for plasma cell granuloma is a complete surgical excision of the lesional mass. Generally when the mass is removed, patients will display an absolute reversal of symptoms. When surgical removal of the granuloma is not applicable due to size or location, the lesions have been found to respond well to radiation therapy as well as glucocorticoids or steroids. While recurrence rate for plasma cell granulomas is very low, they have been reported; therefore, it is recommended that patients come back for yearly follow up visits. Localization Oral gingiva, lungs, vagina, larynx, orbit, spinal cord meninges, breast, pelvic soft tissue, bladder, mesentery, retroperitoneum, kidney, lymph nodes, spleen, pancreas, liver, stomach, heart, thyroid, and trachea. See also Pulmonary hyalinizing granuloma References Medical signs Lesion IgG4-related disease