Acquired blue nevi in older individuals: retrospective case series from a Veterans Affairs population, 1991 to 2013.

IMPORTANCE Apart from the atypical mole phenotype, development of new melanocytic nevi in older individuals is uncommon and considered worrisome for melanoma. We performed a retrospective case series in a Veterans Affairs population from 1991 to 2013 to characterize blue nevi (BN) by patient age at biopsy, location, self-reported duration, and relation to prior or subsequent development of cutaneous melanoma. OBSERVATIONS A total of 204 BN were identified in 194 predominantly male patients (90.7%) who had a mean (SD) age of 62.8 (14.4) years. Clinical duration of 10 years or less was reported by 90.3% of patients with available data (32.0%). Histopathologic examination classified 74.0% of BN as common, 1.5% as cellular, and 24.5% as combined type. No malignant BN were identified; however, 18 primary melanomas were diagnosed, most (72.2%) prior to blue nevus biopsy, including 38.9% in situ and 61.1% with mean (SD) Breslow thickness of 1.02 (0.99) mm. CONCLUSIONS AND RELEVANCE The later patient-reported onset of BN suggests a potential alternative mechanism of nevogenesis compared with common acquired nevi and differs from prior reports of BN development in younger adults. The lack of association with melanoma in older individuals suggests that most benign-appearing BN may be safely observed, even in a cohort at higher risk for skin cancer.