Ipsilateral post-cast hypertrichosis and dyshidrotic dermatitis.

Post-cast hypertrichosis and dyshidrotic dermatitis are not uncommon separately. Yet, the simultaneous occurrence of both conditions in an individual is rare. A patient with both localized hypertrichosis and ipsilateral dyshidrotic dermatitis following multiple fractures and cast application is reported. The clinical presentation, management, spontaneous resolution, and/or response to therapy of post-cast hypertrichosis and dyshidrotic dermatitis that occurred concurrently in an individual were similar to that described when these conditions occur independently. The acquired conditions that may be associated with localized hypertrichosis are summarized and the postulated mechanisms of pathogenesis for dyshidrotic dermatitis are reviewed. The diagnosis of post-cast hypertrichosis in this patient was suspected based upon the distribution and temporal association of the hypertrichosis to the location and placement of his cast, and confirmed by excluding other causes of acquired localized hypertrichosis. Also, the possibility that in this individual either the trauma to his bones, the cast on his arm, or both had an etiologic role in promoting the development of dyshidrotic dermatitis is suggested.