Microcystic adnexal carcinoma: management options based on long-term follow-up.

Microcystic adnexal carcinoma (MAC), a recently described neoplasm that frequently affects the head and neck, presents a confusing problem for the clinician due to its unusual behavior. The individual cells have a bland microscopic appearance, and there is a predilection for neural invasion. Four cases of MAC are reported. All four cases demonstrate the difficulty with pathologic diagnosis. Follow-up of as long as 33 years begins to delineate the protracted nature of MAC. In addition, this paper includes the first report of a case of lymph node metastasis. Although resection may result in a significant defect, negative margins may not be achieved. Despite this, the defect can heal, as demonstrated by the cases described. In addition, MAC may recur many years later, irrespective of the status of the margins at the time of surgery. Given these unusual characteristics and the slowly progressive nature of MAC, strong consideration must be given to less radical surgical procedures, with close follow-up for grossly recurrent disease.