Background: Microcystic adnexal carcinoma (MAC) is a very rare cancer of the skin. It has only been described previously in case reports and small retrospective series.
Objective: To analyze and summarize data from the National Cancer Institute, Surveillance, Epidemiology, and End Results (SEER) database regarding MAC.
Methods: The SEER 1973 to 2004 database was investigated, and patients with MAC were identified. A statistical analysis was performed.
Results: Two hundred twenty-three patients were identified. Predominant site of disease was the head and neck skin (74%). There was only 1 case of recorded metastatic disease. Lymph nodes were pathologically involved in 1%. The 10-year overall survival was 86.4% (Standard Error [SE]: 3.3%). US census population-matched relative survival was 97.7% at 10 years (SE: 5.2%).
Limitations: This study is limited by the retrospective nature of the SEER database.
Conclusions: MAC is locally invasive, and rarely metastasizes to lymph nodes. Overall and population-matched relative survival is excellent.