Necrobiotic xanthogranuloma –⁠ a rare cutaneous complication in a patient with multiple myeloma

Overview

Necrobiotic xanthogranuloma is a rare chronic destructive granulomatous disease of the skin, the incidence of which is being associated with concurrent presence of monoclonal gammopathy. The presence of a lesion might be linked to subjective symptoms such as burning, feeling of tension or pain. Because of its rare incidence, optimum treatment is not known. Despite partial treatment success, the disease tends to recur. The present paper describes a case of an 87 years old patient with this rare cutaneous complication. The patient was followed up from the age of 76 for long-term stable monoclonal gammopathy of unknown significance. In March 2008, painless swelling occurred on the left forearm; histological examination suggested granulomatous changes of uncertain aetiology. A new health complaint occurred in January 2009 in a form of pain in the area of the right Achilles tendon. Subsequently, painful indurations have developed over a period of several months in the crura of both legs, with a maximum in the area of both Achilles tendons. Histological examination of biopsy specimens identified an extensive necrobiotic xanthogranuloma, the finding was the same as that for the formation found in the forearm. Considering this finding and the proposed treatment, trephine biopsy was performed, where 10–15% of plasma cells were detected; the diagnosis was, therefore, reviewed and changed to multiple myeloma. As part of the disease re-evaluation, PET/CT was performed that showed multiple cutaneous and subcutaneous infiltrates with a maximum in both crura with SUV up to 10. Considering the age and co-morbidities, we selected oral combination treatment with cyclophosphamide and prednisone and, considering the high level of pathologically active tissue, analgesic radiotherapy was performed at painful foci in the area of Achilles tendons. This resulted in regression of the foci and, importantly, pain relieve. Unfortunately, soreness of the foci had worsened 1–2 months after radiotherapy completion. Laboratory results showed the minimum response evaluated according to a reduction of monoclonal immunoglobulin. However, no further reduction was observed after 6 cycles and thus the treatment was terminated. Further treatment of the patient is difficult because of his age and co-morbidities; at present, he is on symptomatic treatment only.

Key words:
multiple myeloma –⁠ necrobiotic xanthogranuloma –⁠ cutaneous foci –⁠ granulomatous disease