BackgroundAcrocephalosyndactyly is a syndrome characterized by congenital malformation of the skull with craniosynostosis, midface hypoplasia, and symmetrical webbed fusion of the fingers and toes. We describe a possible pathophysiologic mechanism for chylous ascites that developed several months after menarche in a woman with acrocephalosyndactyly and congenital lymphatic dysplasia.CaseA 25-year-old nulligravid woman with acrocephalosyndactyly, at 18 months after menarche, developed persistent abdominal distension at age 18 years. Laparoscopy at age 25 years revealed chylous ascites with marked chronic peritoneal inflammation, and lymphatic dysplasia with lymphocysts. With hormone manipulation, the chylous ascites fluctuated.ConclusionAfter menarche in a woman with acrocephalosyndactyly, ovarian steroid hormones might have increased lymph production and hydrostatic pressure, causing rupture of congenitally dysplastic lymph vessels resulting in chylous ascites.