Perianal mucinous adenocarcinoma with dysplastic polyps of t
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An 80-year-old man was referred for a perianal swelling with jelly-like discharge and painful defecation of one-year duration. Past medical history was remarkable for hypertension, type 2 diabetes, and recurrent anal fistula over several years, though he never sought treatment. The patient had a negative family history of cancer. Digital examination revealed an elastic hard lesion in the left posterior quadrant with multiple external openings and gelatinous discharge upon squeezing. Immediate skin biopsy of an ulcerated external opening was performed, but the pathological examination showed only non-specific inflammatory material. The patient underwent examination under anesthesia; a trans-sphincteric fistula and multiple cavities filled with gelatinous material were found. A fistulectomy with seton insertion was performed, and the hard tissue lining the multicystic lesion was sent for the histopathological examination that revealed a moderately differentiated mucinous adenocarcinoma.

Chest and abdominal computed tomography (CT) scan showed hypodense areas of fluid density around the anal canal with no evidence of lymph node or distant metastases. Colonoscopy showed no mucosal lesions in the anal canal and multiple polyps of the colon. Tumor markers (CEA, Ca 19.9) were in the normal values range. The patient was informed and involved in the decision-making process. He underwent multiple endoscopic polypectomies and open abdominoperineal resection (APR) of the rectum (Fig. 3). The main procedure (APR) was performed by an experienced colorectal surgeon (senior assistant with more than 10 years of specialized training).

The histopathological diagnosis revealed an extra mucosal mucinous adenocarcinoma with no lymph node metastasis (pT3N0) and multiple dysplastic polyps of the colon. Immunohistochemical study was positive for CK7, CK20, CDX2 and MUC5AC and negative for BRST2. The postoperative recovery was uneventful, and the patient was discharged home after seven days. After a multidisciplinary evaluation, the patient was submitted to adjuvant radiotherapy (45?Gy given in 5 weekly fractions) followed by chemotherapy (Capecitabine) which was discontinued a few months later because of intolerable side effects. He was satisfied with the treatment results. One year later, the patient is in good health except for an incisional hernia, tumor markers (Ca 19.9, CEA) are still normal in range, and there is no evidence of local or distant recurrence at CT scan.