Context:Multiple myeloma is a malignant neoplasm of plasma cells involving the bone marrow. Before entering into aggressive phase, there is a frequent occurrence of extramedullary manifestations. The sites of predilection for extramedullary plasmacytoma are nasopharynx, larynx and upper respiratory tract. Aims: The aim of this present study is to highlight the importance to have high index of suspicion to consider a diagnosis of plasmacytoma based on histomorphological features even in the absence of classical clinical findings. Settings and Design: This study was done as a retrospective study in Coimbatore Medical College Hospital, Coimbatore over a period of 6 months from November 2017 to April 2018 in cases diagnosed as plasma cell lesions. Methods and Materials: 14 Cases of incidentally diagnosed plasma cell myeloma in a period of 6 months were taken. Out of these, 6 cases presented as soft tissue lesions,
3 cases as viscera - organ involvement and 5 cases as lytic lesios of bone. Immunohistochemical confirmation was done with CD 138, kappa and lambda. Results: Fine Needle Aspiration was done for all soft tissue lesions and was reported as plasmacytoma. Subsequently biopsies also proved the same. CD 138 was positive in all cases, kappa in 3 cases and lambda in 11 cases. Two cases were non secretory myeloma with negative serum M protein and urine Bence Jones protein. Conclusions: Soft tissue lesions in patients over the age of 50years should always include a diagnosis of plasmcytoma when sheets of plasma cells are seen. CD 138 showed 100% sensitivity,
with lambda expression in plasma cell myeloma with multiple bony and subcutaneous lesions. Kappa was positive in cases with visceral involvement.