Primary mucinous carcinoma of the skin: a population-based study.

Background: Primary mucinous carcinoma of the skin (PMCS) is a rare malignant tumor deriving from the sweat glands. It is typically located on the head and is often mistaken for a metastasis from a more common primary tumor of the breast or gastrointestinal tract. We present the first population-based study of PMCS.

Materials And Methods: Data on PMCS was obtained from the Danish Cancer Registry, which has recorded incident cases of cancer on a nationwide basis since 1943. We extracted all patients diagnosed 1978-2003 with PMCS.

Results: Fifteen cases of PMCS have been registered during the study period of 26 years, seven in men and eight in women. The patient was typically in his or her 60th or 70th decennium. Seven cases were found on the scalp or neck, five on the eyelids, two on the face, and one on the trunk. Only one recurred, and apart from one regional metastasis, no distant spread or PMCS related deaths were reported.

Conclusion: PMCS is a rare, slow-growing tumor which rarely metastasizes and is associated with low mortality. The age-standardized incidence rate, based on data from a population-based cancer registry of high quality and validity, is less than 0.1 per million. However, the precise number may be higher, since PMCS is an indolent tumor, which may be mistaken for a benign tumor and thus not always examined histologically.