Colorectal endometriosis with a large polypoid lesion

Abstract

A 39-year-old woman was referred to our hospital because of a positive fecal occult blood test result. She had undergone uterine myomectomy 6 years earlier, and she had been treated with levothyroxine for hypothyroidism after thyroidectomy for Graves’s disease. A physical examination revealed a left-sided abdominal mass without tenderness. A laboratory test showed that the levels of serum tumor markers were within normal range. A barium enema revealed a 4-cm protruding lesion in the descending colon (A). The lesion looked like a submucosal tumor with reddish mucosa and dilatated vessels (B). Magnifying endoscopy with crystal violet staining showed 2 types of pit pattern: most was regular and rounded, whereas a small area had an enlarged and irregular pit pattern (C). Surgical histopathologic examination confirmed that the protruding lesion was composed of endometrial glands and stroma surrounded by smooth muscle bundles (D, H&E, orig. mag. ×40). The results of testing for immunohistochemistry, estrogen receptor (ER), and progesterone receptor were positive. Therefore, we diagnosed polypoid endometriosis. Retrospectively, a biopsy specimen from the lesion with irregular pits showed that a few glands were positive for ER (E, Immunohistochemistry for ER, orig. mag. ×200). Colorectal endometriosis usually presents as eccentric wall thickening and surface nodularities, and diagnosis by endoscopic biopsy is difficult. Our case suggests that magnifying endoscopy is useful for diagnosis with target biopsy for intestinal endometriosis.