Two Foot and One Hand Disease

These are the hands of a 35 year-old plumber I saw recently. He was not aware of a dermatitis of his feet, but inspection showed mild moccasin-type T. pedis on both feet and subtle onychomycosis. KOH prep from the right hand was positive for septate hyaline hyphae. We all see two foot and one hand disease regularly. Do you have any theories as to why only one hand is involved? This is a peculiar dermatologic vignette.



Right Hand


Left Hand