Malakoplakia in association with colorectal carcinoma: a series of four cases

Malakoplakia is a characteristic inflammatory condition which is usually seen in the urogenital tract. Gastrointestinal malakoplakia is seen in association with a variety of conditions such as ulcerative colitis, diverticular disease, adenomatous polyps and carcinoma. The purpose of this paper is to report four additional cases of colorectal cancer associated with malakoplakia and review the literature on this association.

All specimens were colectomies for cancer. Routine handling of the specimen with lymph node harvesting was performed. In addition to H&E stains, PAS, Perls' Prussian Blue and von Kossa stains were performed.

Three of the cases were encountered in males and the patients ranged in age from 55 to 64 years. One case each occurred in the caecum/ascending colon and descending colon, while the remaining two were located in the rectum. All four cases were Dukes' stage B tumours. Furthermore, all four cases had spread to pericolic fat and two had perforated. Microscopic examination showed the malakoplakia to be present at the infiltrating edge of the tumours. The draining lymph nodes were involved by malakoplakia to varying degrees in all cases.

From this series and the literature review, malakoplakia associated with colorectal cancer tends to occur in elderly males in the rectum. The malakoplakia is found at the infiltrating front of the tumour and is not admixed with the neoplastic glands. Although lymph node involvement by malakoplakia has been reported only once previously, all four cases in this series showed evidence of involvement. The association does not appear to have any prognostic significance.