Lateral distribution of nonendometriotic benign ovarian cysts

To investigate the left‐ and right‐sided distribution of nonendometriotic benign ovarian cysts, data were collected on 406 women undergoing first‐line surgery for tumours with various histotypes. Considering the unilateral cysts, the observed proportion of left lesions was 65/129 (50.4%) in the serous, 38/79 (48.1%) in the mucinous, 59/134 (44.0%) in the dermoid, 11/21 (52.4%) in the parovarian, and 3/7 (42.9%) in the miscellaneous cysts group, without significant differences from the expected 50%. This contrasts with the finding of a significantly more frequent development of endometriomas on the left ovary, and suggests that the pathogenesis of endometriotic and nonendometriotic cysts is different.