Long-term control of papular dermatitis ("dermal hypersensitivity reaction") with mycophenolate mofetil.

I n dermatology practice, patients frequently present witharecalcitranteruptiondistinguishedby thepresence of edematous, urticarial, intensely pruritic papules.After analysisofpatientbiopsyspecimens, thedermatopathologist will often report a “dermal hypersensitivity reaction” (DHR) characterized by an eosinophil-rich infiltrate. The only clinical differentials that correspond to this pathologicdiagnosis are arthropodbite anddrugeruption, neither of which is clinically relevant to the present case. This skin biopsy finding of DHR was described by Fung as“ahistopathologicpattern forwhichcorrespondingclinicalphenotypeshavenotbeenestablished.” Fung’sdescription of DHR (which he termed urticarial papulosis) is clinicallyandhistologicallyidenticaltowhatwastermedpapular dermatitis byClarket al in1998.Bothstudiescomment on the difficulty of long-term control in affected patients. This skin disease (herein referred to as “papular dermatitis”) is not rare, and it is very challenging to treat. Affected patients rarely respond to topical therapy, and dependence on systemic steroids becomes a significant problem. The following case illustrates my experience with mycophenolate mofetil as a steroid-sparing agent for longterm control of papular dermatitis.