Plasma cells are terminally differentiated B lymphocytes which are typically found in the red pulp of the spleen, medulla of the lymph nodes, tonsils, lamina propria of the entire gastrointestinal tract, mucosa of the nose and upper airway, and sites of inflammation. They are characterised by basophilic cytoplasm with an eccentrically placed nucleus. They range in size from 14 to 20 µm. A plasma cell's main function is to produce immunoglobulins or antibodies. Plasma cell granuloma is a plasma cell lesion which merits discussion because it is typically found in the oral cavity. This lesion is not a neoplastic process, nor is it associated with a monoclonal expansion of a single plasma cell; instead, this is a reactive, inflammatory lesion which usually involves the gingival tissue.