A case of rectal metastasis of prostatic cancer

Abstract

An 81-year-old man was seen at the hospital because of anal bleeding. Colonoscopy revealed an elevated tumor which had grown circumpherentially and encircled halfway around the lower rectum mainly in the left wall. The surface of the tumor showed redness and a strong tendency to bleed. Signet-ring cell carcinoma was identified by a biopsied specimen from the same site. Chest-abdominal CT scan showed no findings suggestive of distant metastasis, and no abnormal findings were noted in the surrounding organs including the prostate. Abdominoperineal resection of the rectum was performed with a diagnosis of primary rectal carcinoma. The resected specimen revealed an ill-defined, irregular, and concave lesion, 6cm in maximum diameter, in the left wall of the lower rectum, and at the oral side, another concave lesion which showed relatively strong redness in color. Histopathological findings of the both lesions revealed that small adenocarcinoma where tubular formation was obscure had invaded from the mucosa to outer membrane. The cytoplasm was pale and light, and positive for PSA. Accordingly rectal metastasis of prostatic cancer was diagnosed.