Type I reaction in leprosy--a histopathological analysis.

Even though type 1 lepra reaction (TIR) is a commonly encountered clinical problem, its histology has not yet been clearly delineated. This study attempts to enumerate the most sensitive parameters for the histological diagnosis of TIR. Case records between March 2007 and September 2007 of patients with TIR were reviewed and the biopsies were evaluated by a pathologist blinded to the previous diagnoses. Twenty three patients were included in the study. The most sensitive parameters in our study were dermal edema, intra-granuloma edema and giant cell size. Though clinical findings should remain the mainstay of diagnosis of TIR, the above mentioned parameters should be evaluated in biopsies of leprosy to look for signs of reaction which might otherwise be missed.