Melanoma mimicking Rosai-Dorfman disease

Despite well-defined clinical and histopathological features of melanoma, atypical presentations mimicking other skin disorders can result in a delayed diagnosis or misdiagnosis and subsequent inappropriate treatment. Rosai-Dorfman disease (RDD) is a rare histiocytic disorder with unique clinical and histopathological features. We report a case of melanoma treated with cryotherapy that mimicked RDD both clinically and histopathologically. We compare this RDD-like melanoma to classic RDD, outlining the importance of clinicopathological correlation prior to treatment, as well as the potential pitfalls in diagnosis after cryotherapy of pigmented lesions.