Extramedullary plasmacytoma of the gingiva.

To cite: Trivedi S, Dixit J, Goel MM. BMJ Case Rep Published online: [please include Day Month Year] doi:10.1136/bcr-2015211606 DESCRIPTION Extraosseous plasmacytoma, also referred to as extramedullary plasmacytoma (EMP), is defined by ICD-10 as a localised plasma cell neoplasm that arises in tissues other than bone. It is considered one of the three variants of plasma cell neoplasms, the other two being multiple myeloma (MM) and solitary bone plasmacytoma (SBP) (also known as medullary plasmacytoma). EMP is a relatively rare lesion, constituting 3% of all plasma cell neoplasms. About 1% of head and neck tumours are EMPs. It is found most commonly in the head and neck region, with 80% of cases occurring in the nasopharynx, paranasal sinuses and tonsils. EMPs occur less commonly in the gingiva. The first case was documented by Martinelli and Rulli in 1968 as a sessile neoplasm in the gingiva from the lower left to right canine, which could be confused with chronic gingivitis. Peison et al reported another case extending from the maxillary right to left canine which was a polypoid growth. The present case report discusses a rarely described extramedullary plasmacytoma of the gingiva. A 45-year-old female patient reported to the Periodontology Department with the chief complaint of swelling of the gingiva in the upper anterior region. The patient complained of difficulty in practicing oral hygiene and a poor aesthetic appearance. The gingival mass was painless, not associated with bleeding and of 6 months’ duration. The patient’s medical history was non-contributory. On intra-oral examination, the gingival mass was oval in shape, with a lobulated appearance and measured 3×1.5 cm. The lesion was reddish, sessile, firm and non-tender, involved the labial gingiva and alveolar mucosa, and extended from the distal surface of the right upper canine to the mesial surface of the left upper central incisor. The surface was smooth with no ulceration or pus discharge (figure 1). There was no associated tooth mobility. A panoramic radiograph and intra-oral periapical radiographs did not show bone loss. Routine blood investigations were within normal limits. A differential diagnosis of chronic inflammatory enlargement, pyogenic granuloma and peripheral giant cell granuloma was considered. An incisional biopsy was performed and the tissue was sent for histopathological examination. The section showed epidermis lined with stratified squamous epithelia. The subepithelial stroma showed diffuse sheets of plasma cells. The plasma cells were mainly mature and variable in size, with an eccentric nucleus and perinuclear halo surrounded by abundant eosinophilic cytoplasm. Quite a few binucleate and multinucleate plasma cells were also seen (figures 2 and 3). Immunohistochemistry for CD 138 showed diffuse membranous and cytoplasmic positivity (figure 4). Immunohistochemistry for cytokeratin, synaptophysin and CD 20 was negative. The laboratory investigations did not show any signs of anaemia, hypercalcaemia or renal failure. Serum protein electrophoresis demonstrated normal levels of IgG and IgA, and Bence-Jones protein was not detected in the urine. A skeletal survey did not show any abnormalities. Thus, MM