Sometimes you have to become a detective… A patient presents with these very itchy, blistering lesions involving the anterior portions of both ankle regions. He notes they have been going on for some weeks, ever since he purchased some new tennis shoes. He denied any known contact allergies and denied any extended sun exposure to the areas. He denied any blistering of the dorsal aspect of his hands. He denied any history or family history of porphyria, and he was a social drinker.
On clinical examination you can see that he has bilateral sheeted vesicles in the exact same location on both feet. There are signs of lichenification (definition click HERE), which goes along with the patient scratching both of these areas. It appears to have almost a square edge, particularly the one on involving the right foot. My suspicions are a contact dermatitis to his tennis shoe, but it is a very unusual pattern. Most shoe related contact dermatitis involves more of the feet. I asked to examine his shoe…
On the inside of the tongue of his shoe was this patch. This is a contact dermatitis to rubber…what the tongue-patch was made of. He was instructed to get himself another pair of shoes. The eruption was treated with triamcinolone cream 0.1%. Mystery solved…