Distribution of ABO blood groups in secretory otitis media and cholesteatoma

The ABO blood groups of 610 patients with documented secretory otitis media (SOM) and of 361 patients with cholesteatoma were compared with those of a control group. In cholesteatoma a normal distribution appeared while in SOM a preponderance of group A or shortage of group O was statistically significant and the incidence ratio was 1.49. In both disease entities a preponderance of males was found. The blood group abnormalities of SOM may indicate hereditary trends and they oppose the theories of SOM being the 'missing link' in the development of cholesteatoma.