Colitis cystica profunda simulating rectal carcinoma. A case report.

Summary A case of colitis cystisa profunda, the patient present­ ing with haematochezia and a rectal mass, is reported. The clinical and pathological features of this .condition are discussed, and the difficulty in distinguishing this lesion from the much commoner rectal neoplasms is emphasised. 5 AIr Med J 1987; 72: 289-290. Colitis cystica profunda (CCP) is a benign lesion of the lower colon and rectum. Once considered rare, I it is now being diagnosed with increasing frequency. 2 The presenting symp­ toms and signs are rectal bleeding, tenesmus and a rectal mass that may simulate much more common reetal carcinoma. The typical histological feature of CCP is glandular invasion of the submucosal layer which often makes differentiation from adenocarcinoma difficult. Some patients are reported to have undergone unnecessary radical excision of the rectum3 because of an erroneous histological diagnosis of carcinoma. A patient with CCP was recently treated at this hospital and she presented a familiar diagnostic problem. Case report . A 25-year-old woman was referred for excision of a rectal lesion. There was a 2-year history of rectal bleeding, mucous discharge and tenesmus, which had been diagnosed and treated initially as ulcerative colitis. The referring physician had done a biopsy of a rectal polyp, which was found on histological examination to be a tubovillous adenoma with marked cellular dysplasia. On examination the patient was fit and healthy. During rectal examination a flat, soft, non-polypoid lesion was palpable. At endoscopy the lesion was seen to occupy the anterior and left lateral walls of the rectum, extending 9 cm up from the anal verge. Colonoscopy excluded more proximal lesions. Under general anaesthesia the rectal submucosa was inftltrated with an adrenaline-containing solution and submucosal excision of the lesion was performed transanally. Parts of the lesion were fixed to the underlying muscle which had to be removed. The pathology report read: '... large polypoid mass with irregular ulcerated mucosa ... mucosa and submucosa with derangement of mucosal panem and mild-to-moderate atypia in crypt epithelium. There is a well-differentiated adenocarcinoma infiltrating into the submucosa where there are large lakes of extracellular mucin containing signet-ring cells. There is no infiltration of the muscle layers.' (Figs 1 and 2.)