Surveillance, Epidemiology, and End Results (SEER) database analysis of microcystic adnexal carcinoma (sclerosing sweat duct carcinoma) of the skin

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. To analyze and summarize data from the National Cancer Institute, Surveillance, Epidemiology, and End Results (SEER) database regarding MAC. The SEER 1973 to 2004 database was investigated, and patients with MAC were identified. A statistical analysis was performed. 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%). This study is limited by the retrospective nature of the SEER database. MAC is locally invasive, and rarely metastasizes to lymph nodes. Overall and population-matched relative survival is excellent.