Four subtypes of adenomyosis assessed by magnetic resonance imaging and their specification

OBJECTIVE: The aim of the present study was to differentiate and specify the subtypes of adenomyosis. STUDY DESIGN: Surgically treated adenomyosis (n = 152) was sub-categorized retrospectively into 4 subtypes on the basis of magnetic resonance imaging geography. Subtype I (n = 59) consisted of adenomyosis that occurs in the uterine inner layer without affecting the outer structures. Subtype II (n = 51) consisted of adenomyosis that occurs in the uterine outer layer without affecting the inner structures. Subtype III (n = 22) consisted of adenomyosis that occurs solitarily without relationship to structural components. Adenomyosis that did not satisfy these criteria composed subtype IV (n = 20). Stepwise logistic regression analysis was used for specification of the subtypes. RESULTS: Subtypes I-III were suggested as a product of direct endometrial invasion, endometriotic invasion from the outside, and de novo metaplasia, respectively. Subtype IV was a heterogeneous mixture of far advanced disease. CONCLUSION: Adenomyosis appears to consist of 3 distinct subtypes of different causes and an additional subtype of indeterminate cause.