Rapid development of an axillary mass in an adult: a case of cystic hygroma.

Cystic hygroma is a congenital anomaly of lymphatic origin, which mainly develops during childhood. Its development in adulthood, however, has been proposed to be related to several predisposing factors such as trauma, infection, tumor growth or iatrogenic stimuli. The development of cystic hygroma in the extremities of adults is extremely rare and moreover, its development in the axillary region has, to our knowledge, been reported only once in the literature. We describe an unusual case of a cystic hygroma which developed rapidly in the axillary region of a female patient in the absence of any predisposing factor. The diagnostic workup and the need for surgical excision of the mass to obtain an accurate, histologic diagnosis is presented.