Circumscribed Tylosis (inflammatory), heel of left foot. H. Radcliffe Crocker, 1896. Tylosis is a genetic disorder characterized by thickening (hyperkeratosis) of the palms and soles, white patches in the mouth (oral leukoplakia), and a very high risk of esophageal cancer. This is the only genetic syndrome known to predispose to squamous cell carcinoma of the esophagus.