RECTAL ENDOMETRIOSIS MIMICKING SOLITARY RECTAL ULCER SYNDROME

We report a unique case of rectal endometriosis mimicking solitary rec tal ulcer syndrome. Several rectal biopsies were performed before the correct diagnosis of rectal endometriosis was made. The lesion had str iking histologic features resembling colitis cystica profunda. The pre sence of two types of glands, i.e., colonic glands with marked depleti on of mucin and endometrial glands, were readily apparent on immunohis tochemical stain using anticarcinoembryonic antigen showing positive c ytoplasmic stain for colonic glands but negative for endometrial gland s. However, the distinction between colonic and endometrial glands was very difficult on hematoxylin-and-eosin-stained slides. Endometrial s troma was identified only in the sixth biopsy specimen. Although rare, rectal endometriosis should be considered in the differential diagnos is of solitary rectal ulcer syndrome.