Adenomatous hyperplasia of the endocervix.

Adenomatous hyperplasia of the endocervix or "tunnel clusters" have long been felt to be the result of obstruction of endocervical gland-like clefts. However, in some instances it is possible to demonstrate that obstruction is not present. The histologic features of this entity are similar to those of benign mucinous neoplasms of the upper genital tract, and therefore it seems reasonable to suspect that adenomatous hyperplasia is, in fact, a proliferative metaplasia or neoplasia of the endocervical gland epithelium. While clinically unimportant, we believe that this is an additional example of the fundamental embryologic kinship of the entire genital tract epithelium.