Extraparenchymal ovarian and testicular Leydig cells: ectopic/heterotopic or orthotopic?

Purpose We are conducting a prospective study trying to determine, in both sexes, the frequency of appearance of ectopic Leydig cells, their preferred location, their relationship with nerve structures and the possible causes of their appearance. Methods We have studied 86 cases that were removed according to different clinical indications for pathological study: uterine leyomiomas ( n = 12), ovarian cystadenoma ( n = 4), endometrial hyperplasia ( n = 8), endometrial carcinoma ( n = 12), cervical carcinoma ( n = 4), seminoma ( n = 4), fallopian tube ligatures ( n = 24), vasectomies ( n = 8), nonspecific orchiepididymitis ( n = 2), and unknown ( n = 8). Results We have observed ectopic Leydig cells in 13/86 cases (15.11%), 9/72 in the female samples (12.50%) and 4/14 in male samples (28.57%). The most frequent location was the mesosalpinx (4 of 13: 30.76%). Conclusions These high figures lead us to believe that the ectopia of Leydig cells is not really a pathologic entity, but a finding related to specific functions yet to be determined.