Clinical and Dermoscopic Features of Vulvar Melanosis over the Last 20 Years

Importance: Vulvar melanosis is a common pigmentary change that accounts for most pigmented vulvar lesions. It presents as single or multiple asymptomatic macules or patches of varying size and color that may be asymmetric with poorly defined borders. The differential diagnosis of melanocytic lesions includes melanoma, which creates anxiety for patients and the physicians who diagnose the condition and treat the patients. Objective: To evaluate the clinical and dermoscopic features of vulvar melanosis and their changes over time. Design, Setting, and Participants: In this cohort study, patients with vulvar melanosis were recruited and followed up in the Department of Dermatology, University of Florence, Florence, Italy, between January 1, 1998, and June 30, 2019. Data on patient characteristics and on both the clinical and dermoscopic features of the vulvar lesions were collected. Each lesion was photographed clinically and dermoscopically at initial evaluation and at annual follow-up visits. Main Outcomes and Measures: The clinical, dermoscopic, and histopathologic features of vulvar melanosis and their changes over time. Results: This cohort study included 129 women (mean age at diagnosis, 46 years [range, 19-83 years]) with vulvar melanosis. A total of 87 patients (67%) with vulvar melanotic lesions were premenopausal, and 84 patients (65%) had received some type of hormone therapy. The most frequent location for vulvar melanosis was the labia minora (55 [43%]), followed by the labia majora (33 [26%]). In 39 of 129 cases (30%), the lesions increased in size and changed color after initial evaluation but ultimately stabilized. No malignant evolution was documented in any patient during a median follow-up of 13 years (range, 5-20 years). Conclusions and Relevance: This study suggests that vulvar melanosis was a benign entity, and changes in lesions over time did not signify malignant transformation. An association between hormonal status and vulvar melanosis may be hypothesized.