ABSTRACT
Anaplastic myeloma has various synonyms such as dysplastic myeloma, aggressitve phase myeloma, or immunoblastic sarcoma. This is known to be an extremely aggressive subentity of plasma cell myeloma, and the diagnosis can usually be delayed because of the lack of the typical morphologic characteristics of myeloma. We describe here a 45-year-old man with anaplastic myeloma, whom we had difficulties with in initial diagnostic workup. The patient was admitted to the hospital due to gum bleeding for 2 weeks. A few abnormal cells were found in the peripheral blood. In bone marrow aspiration smears, the normal hematopoietic cells were replaced by numerous anaplastic cells. An immunophenotype study showed only a dim expression of CD56 antigen, while other routine surface antigens as well as CD45 were all negative. Additional studies showed a moderate positivity of CD38 and cytoplasmic lambda light chain. Serum immunoelectrophoresis confirmed monoclonal lamda light chain production, which led to the diagnosis of anaplastic myeloma. Because the morphologic feature is confused with other lymphoproliferative disorders, the diagnosis of anaplastic myeloma could be delayed unless a high degree of suspicion is made. Cytoplasmic light chains as well as CD56 will be helpful in initial immunophenotyping workup when the neoplastic cells show anaplastic features.