Myometrial hyperplasia in pediatric, adolescent, and young adult uteri.

Objectives: To evaluate if myometrial hyperplasia is a congenital variation in myometrial differentiation, or an acquired structural disorder of the myometrium, this study evaluated whether myometrial hyperplasia was present in uteri of children, adolescents, and young adults.

Methods: We studied 19 pediatric/young adult uteri in cases with no clinical history of uterine disease. Random photomicrographs at 100x, taken at 1, 5, and 10 mm beneath the endometrium, were assessed for increased cellularity and nucleus/cell ratio, as compared to normal myometrium in the outer third of the same uterus.

Results: Myometrial hyperplasia was generally absent in prepubertal uteri, first appeared in adolescent uteri just beneath the endometrium, and was found at 5 mm depth only after age 18. It decreased with depth beneath the endometrium (P<0.05).

Conclusions: Myometrial hyperplasia is not a congenital anatomic variation in myometrial differentiation, but rather an age-related acquired structural variation. Its relationship to common adolescent symptoms of dysmenorrhea and anovulatory bleeding remains unknown and unexplored.