Adenosquamous carcinoma of the colon

Abstract

Two cases of primary adenosquamous carcinomas of the sigmoid colon and rectum are presented. Clinical features and pathologic findings of both primary and metastatic lesions are reported (including immunohistochemistry and electron microscopy). We emphasize that the presence of a metastatic squamous tumor in a patient with an unknown primary does not exclude the possibility of colonic carcinoma. Comparison with other reports in the American medical literature indicates that these are very aggressive tumors that may have a worse prognosis than the more common form of colonic adenocarcinoma. Furthermore, the squamous component, in particular, may have a greater potential for metastasizing and can do so as an undifferentiated-appearing carcinoma. In view of this, the authors suggest that very poorly differentiated areas within colonic adenocarcinomas should be very carefully evaluated by means of immunoperoxidase stains and/or electron microscopy in an attempt to identify squamous features.

Basaloid Squamous Cell Carcinoma of the Rectum: A Rare Entity

“…As regards the basaloid variety of squamous cell carcinoma outside the anal canal, it may arise from cloaco- genic embryologic nests, squamous metaplastic epithelium, or totipotential basal cells [12]. In mixed adenosquamous variety, Cerezo and others suggested that all such lesions be carefully evaluated by means of immunoperoxidase stains and/or electron microscopy in order to identify squamous features [20,21]. Symptoms, investigations, and assessment of patients with the divergent histologic subtypes of squamous cancer of the colon and rectum, including basaloid tumors, are similar to those of colon adenocarcinoma, as is evident in our case [5,22].…”

“…Neoplastic nests invaded the wall of the rectum localized, focally, in the close proximity of the rectum's serosal surface. Seven (7) out of twenty (20) regional lymph nodes and a mesenteric lymph node were found to be infiltrated by malignant cells. The postoperative recovery of the patient was uneventful and she was discharged on postoperative day 9.…”

Carcinoma adenoescamoso do reto: relato de caso

“…Existe uma certa tendência de aumento do componente escamoso nas metástases. 6 Em nosso caso, as metástases foram decorrentes da disseminação de adenocarcinoma para o fígado.…”

“…1,7 A suspeita deve surgir em adenocarcinoma com áreas de tumor muito pouco diferenciado devendo ser pesquisados com imunoperoxidase e/ou microscopia eletrônica para identificação do componente escamoso. 6 O prognóstico de tumores estádio I e II com linfonodo negativo (Dukes A e B) é semelhante ao adenocarcinoma. Porém, na doença nodal, o prognóstico é pior.…”

“…5 A patogênese não é bem definida e existem diversas teorias para explicar a existência das duas linhagens celulares concomitantes. 2,3,6 A localização dos tumores é principalmente em reto e porções distais do cólon, com apresentação clí-nica e macroscópica semelhante ao adenocarcinoma, porém com menor sobrevida. 1,4 O objetivo deste estudo é relatar um caso de tumor adenoescamoso do reto e apresentar revisão da literatura.…”