RESUMO
A 66-year-old man with a swollen right inguinal lymph node (LN) had pain on the lower side of the back. Computed tomography revealed bone disease in the back and swollen right inguinal LNs. Laboratory studies showed anemia and serum immunoglobulin G-lambda (IgG-λ) type monoclonal protein. The bone marrow contained 39.6% plasma cells. He was diagnosed with IgG-λ type multiple myeloma (MM). However, the pathological findings of the right inguinal LN were mixed cellular classical Hodgkin lymphoma (HL). The administration of melphalan, prednisone, and bortezomib (MPB) was started for MM; however, swelling in the right inguinal LN increased. After three cycles of MPB, the administration of doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD) was started for HL. However, HL was refractory to ABVD. Pancytopenia subsequently progressed and rapid swelling occurred in his LNs. He died 7 months after diagnosis. Multiple myeloma was diagnosed, based on the typical symptoms, although the pathological findings of the LN indicated a diagnosis of HL. We analyzed the molecular relationship between MM and HL cells using a direct sequencing method. The sequencing results demonstrated that the variable-diversity-joining (VDJ) region of the IgH gene was identified with 94.4% of IGLV3-32*01 in the bone marrow sample at diagnosis. Furthermore, clonotypic IgH sequence was identified in CD30-positive cells from the LN. These results suggested that the clonal HL cells were derived from the same source as the clonal MM cells and demonstrated that MM and HL in this patient may have originated from the same B cell progenitor.