To B or not to B: is tylosis B truly benign? Two North American genealogies.

Tylosis is a rare, autosomal dominant syndrome presenting with hyperkeratosis of the palms and soles of the feet. Two types have been identified. Late onset tylosis (type A) is reported to be associated with a high incidence of esophageal carcinoma, whereas early onset tylosis (type B) appears to be a benign disorder. This distinction has significant implications for surveillance and prognosis. We report two families exhibiting early onset type B tylosis, spanning five and seven generations, respectively, and believe these to be the first two extensive genealogies of tylosis type B reported in North America. They serve to verify the features of type B tylosis and its benign prognosis. The world literature is reviewed and clinical relevance is discussed. Recommendations for follow-up of afflicted individuals are proposed.