Cysts and Sinuses of the Neck*
Cysts and sinuses of the neck may be roughly classified into those which occupy the midline and those which lie lateral to the midline. This discussion deals with cysts and sinuses lying in both locations but is limited to those which arise from the deeper-lying embryologic structures. Thus dermoids, simple retention cysts of the skin, etc., have been excluded except as they are involved in the differential diagnosis.
The nomenclature of the subject is in a rather chaotic state. There is considerable evidence to show that not only do the so-called “branchiogenic” or “branchial” cysts and fistulae fail to arise from the branchial apparatus but that, in like manner, the “thyroglossal” cysts and sinuses do not arise directly from the thyroglossal apparatus. Because the terms “branchial” and “thyroglossal” have become so ingrained in the literature, they have been retained in this discussion and used synonymously with the simpler terms “lateral” and “median” respectively.
Branchial Cysts and Fistulae
Etiology and Embryology: In the human embryo, the branchial apparatus is a very transitory structure which is first evident during the latter half of the first month of intra-uterine life and has completely disappeared by the end of the second month. This apparatus arises in the region of the neck and consists of five or six bars or arches separated by corresponding depressions or grooves. The arches are termed the branchial or visceral arches and the intervening depressions, as viewed from the outside, are called the branchial grooves. Similarly the lining. . .