Clinical Features and Treatment Outcomes of Patients With Necrobiotic Xanthogranuloma Associated With Monoclonal Gammopathies.

Introduction: Necrobiotic xanthogranuloma (NXG) is a rare chronic granulomatous disorder of the skin associated with a monoclonal gammopathy.

Patients And Methods: The present report describes the findings from a single tertiary medical center retrospective study, including the clinical features of 35 patients with NXG and monoclonal gammopathy from 2000 to 2015 and their subsequent disease course and treatment response. The median age at diagnosis was 56 years (range, 26-88 years).

Results: Most patients had a plasma cell dyscrasia consisting of monoclonal gammopathy of undetermined significance in 28 patients and smoldering multiple myeloma in 5 patients; the remaining 2 patients had chronic lymphocytic leukemia. An IgG isotype of monoclonal gammopathy was present in almost all the patients (97%). The most common site of cutaneous involvement of NXG was periorbital (66%). The treatments were heterogeneous and included excision, intralesional injection, radiotherapy, and systemic chemotherapy. The median follow-up period was 46 months (range, 4 to 234 months). The median overall survival had not been reached at the analysis, and 80% of the patients were still alive. Eight patients (23%) had disease progression to multiple myeloma at a median of 67 months (range, 21 to 107 months), demonstrating that although the clinical course is generally indolent, malignant transformation is not uncommon. At the last follow-up visit, 80% had signs of either clinical improvement or stable skin disease.

Conclusion: Cutaneous objective responses can be achieved with treatment of lymphoplasmacytic malignancies.