口腔原発髄外性形質細胞腫の3例の免疫組織学的検討

Immunohistological Examination of Three Cases with Extramedullary Plasmacytoma originated in Oral Cavity

　はじめに

　形質細胞腫の診断は，骨髄原発の場合即ち多発性骨髄腫の時は比較的容易であるが，骨髄外原発の髄外性形質細胞腫の場合は種々の悪性小円形細胞腫瘍との鑑別が必要であるうえ，免疫組織学的にEpithelial Membrane Antigen （以下EMA）やビメンチンが陽性所見を呈する場合には更に慎重に鑑別されねばならない^1,2）。今回われわれは，EMAやビメンチンが陽性の口腔原発髄外性形質細胞腫の3例を経験したので，免疫組織学的検討を加え報告する。

Extramedullary plasmacytomas originated in the oral cavity in 3 patients; a 20-year-old female, the left tonsil, a 55-year-old female, the epipharynx, a 84-year-old female, the hard palate, were examined immunohistologically. Epithelial mem-brane antigen (EMA) was positive in 2/3 cases, Vimentin in 1/3 and Leukocyte common antigen (LCA) in 0/3.

EMA and Vimentin were positive in plas-macytoma with high frequency, but LCA-positivity became negative when B lymphocytes differentiate to plasmacytoid cells.

These facts indicated that the erronous diagnosis of carcinoma or sarcoma could be made in cases of extramedullary plasmacytomas.