Multiple myeloma with CD138 changed from positive to negative: A case report

Background Multiple myeloma (MM) is a common malignant disease of the blood system, caused by the neoplastic proliferation of plasma cells that accumulate in bone marrow (BM). Here, we report a case of MM patient with CD138 marker changed from positive to negative. Methods BM and peripheral blood samples from a 48-year-old patient with MM were examined and analyzed by conventional morphology, flow cytometry, and immunodetection. Results Imaging examination and clinical manifestations fulfilled criteria for MM. On the first hospitalization, flow cytometry showed that the cells were CD138(+)/CD38(+)/CD19(-)/CD56(+). However, on the fifth hospitalization, flow cytometry revealed that the cells were CD138(-)/CD38(+)/CD19(-)/CD56(+). Conclusions MM is diagnosed on imaging and clinical manifestations, immunophenotype of flow cytometry is also an important method of diagnosing MM. However, the discovery of atypical immunophenotypes cannot prevent the diagnosis of MM, even provide a clue of disease progression.