Squamous metaplasia of the ovarian surface epithelium and subsurface fibrosis: distinctive pathologic findings in the ovaries and fallopian tubes of patients on peritoneal dialysis.

Peritoneal dialysis is commonly used to treat patients with end-stage renal disease. Patients on long-term peritoneal dialysis develop edema and fibrosis of the peritoneal membrane, but the morphologic effects on the organs of the female genital tract are obscure. We noted squamous metaplasia of the ovarian surface epithelium in a patient on peritoneal dialysis, leading us to review all cases of peritoneal squamous metaplasia in our surgical pathology database. Squamous metaplasia of the peritoneum is rare, and we found only 3 examples. Two cases occurred in women on long-term peritoneal dialysis who were operated on for benign ovarian cystadenomas. The gynecologic pathology findings were similar in both cases, with immature and mature squamous metaplasia present extensively on the surfaces of the ovaries, and in 1 case, on the surface of the ipsilateral fallopian tube. The metaplastic epithelium was keratin and p63 positive. Staining for p63 highlighted areas where the metaplastic epithelium was only 1- or 2-cell layers thick and areas of more developed metaplasia. In addition, there was a broad band of fibrous tissue 1- to 2-mm thick beneath the surfaces. A third case of peritoneal squamous metaplasia involved the serosal surface of the small intestine in a woman who experienced complications after bariatric surgery. There were small nodules of squamous metaplastic epithelium on and beneath the serosal surface of the intestine, surrounded by acute and chronic inflammation and fibrosis. Based on our experience and limited information in the literature, there are 2 distinct patterns of squamous metaplasia of the peritoneum: a diffuse pattern of metaplasia associated with bandlike subsurface fibrosis in peritoneal dialysis patients and a micronodular pattern of metaplasia associated with inflammatory conditions. Dialysis-associated changes involving the ovary and fallopian tube form a mechanical barrier that could contribute to the low rate of fertility in peritoneal dialysis patients.