Cutaneous Crohn's disease with superimposed psoriasis: A unique case with overlapping histology.

Crohn's disease (CD) is an idiopathic, chronic inflammatory disorder of the gastrointestinal tract. We recently encountered a unique case in which a patient with longstanding CD presented with skin lesions with histopathologic features of both psoriasis and granulomatous inflammation suggestive of cutaneous CD. To our knowledge, this has not been described concomitantly in the same patient, in the same lesions. Review of the literature suggests that the intersection of these 2 histopathological reaction patterns may not be pure coincidence. Clinical-pathologic correlation of this case will be discussed, along with a review of the potential mechanisms of this unique disease presentation.