An ABO-blood group abnormality leading to the detection of a colon-carcinoma.

A patient who had been admitted to hospital for surgical treatment of inguinal hernias was found to have group phenotype of A1B in the presence of a non-auto-anti-B. No previous records of the patient's blood group were available. The serological workup including absorption and saliva inhibition studies yielded a high probability for an acquired B-antigen which is known to be often associated with carcinoma of the colon. Subsequent coloscopy revealed the presence of a carcinoma of the sigmoid, unaccessable to palpation. To our knowledge this is the first report in the literature that the serological diagnosis of an acquired B-antigen led to the detection of a hitherto undetected carcinoma.