A similar co-occurrence of ARID1A mutations and alterations in the PI3K pathway genes in endometriosis-associated ovarian carcinomas (such as two epithelial ovarian carcinoma subtypes, the ovarian clear cell carcinomas and the endometrioid ovarian carcinomas which have been molecularly and epidemiologically linked to endometriosis) has been observed in our patients. The gene discussed is PIK3CA; the disease is ovarian carcinoma.