THE ETIOLOGY OF LATERAL CERVICAL (BRANCHIAL) CYSTS - PAST AND PRESENTTHEORIES

Four theories have been suggested to explain the aetiology of lateral cervical cysts. Ascherson (1832) suggested that the cysts arose due to incomplete obliteration of branchial cleft mucosa, which remained dor mant until stimulated to grow later in life. His (1886) suggested thes e cysts were vestiges of the precervical sinus. Wenglowski (1912) beli eved lateral cervical cysts developed from the third pharyngeal pouch (thymopharyngeal duct). A number of investigators during the 19th cent ury noted the close relationship between lateral cervical cysts and ly mphoid tissue (Lucke, 1861). Luschka (1848) suggested that cystic dege neration of cervical lymph nodes was the mechanism by which lateral ce rvical cysts were formed. This theory received little support until Ki ng (1949) studied the histology of a large number of lateral cervical cysts and concluded that these cysts resulted from cystic transformati on of cervical lymph nodes. The evidence for and against these theorie s of aetiology is discussed. The debate is centred on a study of 20 pa tients with lateral cervical cysts operated on in the Department of Ot olaryngology, Bedford Hospital, between January 1986 and December 1991 . In all twenty cases the wall of the cyst was found to be composed of lymphoid tissue, histologically identical to that present in lymph no des. The mean age of presentation was 31 years, and in no case was a t ract or cord found which connected the cyst to the skin or pharynx. Th e evidence strongly suggests that lateral cervical cysts develop from the cystic transformation of cervical lymph nodes. Mechanisms by which this may occur are discussed.