Radiation Therapy for Secondary Cutaneous Plasmacytomas

We are reporting a case of a 75-year-old man with multiply recurrent IgA-lambda multiple myeloma status post multiple rounds of chemotherapy, autologous stem cell transplantation, and palliative radiation therapy for diffuse bone lesions. Approximately 15 years after original diagnosis, he developed secondary cutaneous plasmacytomas of the right arm, right chest wall, and right upper back over the course of several months. He underwent palliative involved field 3D conformal photon or en face electron therapy concurrently with various chemotherapy regimens and achieved good to complete response with palliation of pain at the irradiated sites. He died of complications related to his disease approximately 7 months after developing skin lesions. The case presented is unique for dermal involvement of myeloma treated with palliative involved field radiation. 1. Introduction Multiple myeloma (MM) is a plasma cell malignancy with clonal proliferation of neoplastic plasma cells in bone marrow with monoclonal immunoglobulin production leading to skeletal destruction. Cutaneous involvement from these tumors is usually in the setting of direct extension from underlying plasmacytomas. Skin plasmacytomas not associated with underlying lesions, also known as secondary cutaneous plasmacytomas (SCP), are rare with less than 100 reported cases [1–17]. Development of these lesions is often a reflection of high systemic tumor burden in the late stages of disease and is a poor prognosticator with most patients dying within 12 months [1, 2]. Few cases are reported in the literature documenting use of radiation therapy to treat SCPs [1, 2, 11, 14]. Appropriate management of these cases, in regards to use of radiation therapy, is not established. This report presents a case of SCPs treated with involved field radiation therapy. 2. A Case Report In September 1996, a 58-year-old white man presented with left scapular discomfort and subsequent workup suspicious for plasmacytoma. The original bone marrow biopsy revealed plasmacytosis of 30%, and immunofixation demonstrated high IgA and free lambda light chain. Original laboratory tests revealed 1.2？g/dL M protein with normal albumin, hemoglobin, renal function, calcium, and LDH. He was without Bence-Jones proteinuria. Imaging demonstrated left scapular, right clavicular, sternal, and bilateral humeral lytic bony lesions. He was diagnosed with Durie-Salmon Stage IIIA, International staging I, and IgA-lambda MM. He underwent 3 cycles of bortezomib, doxorubicin, and dexamethasone (VAD) chemotherapy with excellent response. Labs and