Testicular Plasmacytoma Masking as Epididymo-orchitis in a Known Multiple Myeloma Patient

Extramedullary plasmacytoma (EMP) is defined as a localized plasma cell neoplasm that arises in tissues other than the bone. The most common sites of involvement of EMP are the upper airways followed by lymph nodes, gastrointestinal tract, thyroid gland, skin, brain, liver, and lungs. Testicular plasmacytoma has a very rare occurrence with about 70 cases reported in literature to date.

We describe a 52-year-old-male with a diagnosis of multiple myeloma presenting with lytic lesions of the axial skeleton. He had lambda light chain restricted, R-ISS stage II with high risk cytogenetics as he tested positive for t(4;14). He underwent four cycles of cyclophosphamide, bortezomib and dexamethasone followed by auto-peripheral stem cell transplantation. He was kept on ixazomib, lenalidomide and dexamethasone maintenance therapy, but relapsed soon after and was diagnosed with plasmacytoma of the left lung. Therapy was switched to daratumumab, carfilzomib and dexamethasone and the patient received radiation of his left lung. He then developed left painless testicular mass which was treated with six weeks course of antibiotics. However due to persistence of concerning features on scrotal ultrasound post-treatment, the patient underwent radical orchiectomy with pathology coming back positive for plasma cells.

The testes serve as a sanctuary site for hematological malignancies due to the presence of the testicular-blood barrier. Hence, it is imperative to keep a high index of suspicion for testicular plasmacytoma in the right clinical context when evaluating a patient with known multiple myeloma.