Microcystic Adnexal Carcinoma: A Rare, Commonly Misdiagnosed Malignancy.

Microcystic adnexal carcinoma (MAC) is a rare, malignant cutaneous neoplasm that often presents as an inconspicuous, benign appearing lesion. Patients most commonly are asymptomatic and present for improved cosmesis, however perineural invasion may result in local numbness, paresthesia or pruritus. Although distant metastasis is rare, MAC has an increased propensity for local invasion, often resulting in significant morbidity as late presentation and misdiagnosis are common. A high index of suspicion is imperative, and deep tissue biopsy with defining histologic characteristics is required for diagnosis. Mohs micrographic surgery is currently the standard of care, providing the highest possibility for long-term cure. We present a case report of a 43-year-old male Air Force U-2 pilot with a benign presentation and initial clinical misdiagnoses of MAC, who underwent Mohs micrographic surgery followed by cervicofacial flap reconstruction of a 5.5 × 3.5 cm defect. We also identify increased radiation exposure of U-2 pilots as a potential risk factor for the early development of MAC, emphasizing the importance of exploring patient risk factors while having a high index of suspicion to aid in early diagnosis. Published by Oxford University Press on behalf of the Association of Military Surgeons of the United States 2019. This work is written by (a) US Government employee(s) and is in the public domain in the US.