Plasma cell granuloma

PCGs were first discovered and described in 1973 by Bahadori and Liebow. PCGs are characterized by the proliferation and infiltration of different inflammatory cells with the main cell observed in highest concentrations being plasma cells. Microscopically, plasma cell granulomas, demonstrate a lesional pattern of inflammatory pseudotumor. == Etiology ==

The etiology of plasma cell granulomas is widely unknown, however, there are a few ideas on what causes the condition to develop. Studies suggest that one possible causative factor is the presence of a foreign body. A foreign body is likely to give off an antigenic cue causing the accumulation of polyclonal IgG4 positive plasma cells. Others suggest that plasma cell granulomas have an autoimmune origin. PCGs have also been found to be drug and/or hormone induced. == Pathology ==

Diagnosis/Differentiation Since plasma cell granulomas have the ability to occur at any site, even though they are uncommon, it should be included in differential diagnostics in regard to plasma cell neoplasms. Determining Plasma Cell Clonality The clonality of plasma cells is most accurately determined by two different methods. 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 ==