Relapsing Cutaneous Multiple Myeloma Responding to Immunochemotherapy: A Rare Case Report.

Multiple myeloma (MM) is characterized by the neoplastic proliferation of plasma cells. The diagnosis of this disease is often suspected through a constellation of clinical signs and symptoms of hypercalcemia, renal failure, anemia, and M-spike proteins. It is the second most common hematological malignancy after non-Hodgkin lymphomas. However, cutaneous MM is an extremely rare entity, and it is associated with poor prognosis. It presents as diffuse erythematous rash or violaceous nodules on the skin. Most common sites of involvement are chest, lower extremities and back. It can be triggered by a local extension of the tumor which is the most common way, surgical procedures and hematogenous spread. An 82-year-old African American male was diagnosed with MM since 2008. He underwent autologous peripheral stem cell transplantation (ASCT) twice in 2010 and 2014; and he had a history of multiple chemotherapy regimens in the past. He had violaceus chest nodules, and the biopsy confirmed the diagnosis of cutaneous MM in 2013. The patient was treated with pomalidomide, panobinostat and dexamethasone with a complete response (CR) to treatment. One year later, the patient developed new skin nodules. Repeat biopsy confirmed the diagnosis of MM again. Patient was treated with daratumumab and had CR to treatment without any new M-spike. Cutaneous lesion is an exceedingly rare presentation of MM. It either present as reddish rash or violaceous nodules involving chest, lower extremities and back. It has a poor prognosis and can be rapidly fatal. Our case is unique because our patient responded to the newer chemotherapy, and lesions resolved despite poor prognosis of this condition.