Nonpigmented endometriosis: clinical, laparoscopic, and pathologic definition.

We describe the morphologic characteristics and clinical importance of peritoneal lesions that have the histologic features of endometriosis but are devoid of the pigmented stigmas typical of this disease. A total of 137 laparoscopic biopsy specimens were taken of nonpigmented peritoneal lesions in 77 patients, among whom 70 were infertile. Seventy-three biopsy specimens showed endometrium-like glands and stroma, and another 12 showed only endometrioid stroma; no such histologic features of endometriosis were present in 10 biopsy specimens of normal uterosacral ligament peritoneum (p = 0.005, Fisher's test). Nonpigmented lesions that were commonly endometriotic were: white opacified peritoneum (endometriosis in 81% of n = 52 biopsy specimens), red flamelike lesions (81% of n = 16), and glandular lesions (resembling endometrium at hysteroscopy) (67% of n = 21). Lesions that were sometimes endometriotic were: subovarian adhesions (50% of n = 4), yellow-brown peritoneal patches (47% of n = 19), and circular peritoneal defects (45% of n = 11). However, thickened cribriform peritoneum usually was not endometriotic (9% of n = 11) and vesicular excrescences were, in every case, reactions to oil-based salpingographic medium (n = 5). Six patients underwent another laparoscopy within 6 to 24 months and each had developed pigmented endometriotic lesions in previously nonpigmented but abnormal areas. Visualization of pigment is not necessary to diagnose endometriosis, and definition of its early, nonpigmented appearance keeps the clinical category of "unexplained infertility" exclusive.