Drug reaction with eosinophilia and systemic symptoms (DRESS): A histopathology based analysis.

<bold>Background: </bold>The data on the histology of cutaneous lesions of drug reaction with eosinophilia and systemic symptoms (DRESS) is limited.<bold>Aims: </bold>To study the histopathology of cutaneous lesions of drug reaction with eosinophilia and systemic symptoms (DRESS) and to identify any features with diagnostic or prognostic significance.<bold>Methods: </bold>All patients admitted to the dermatology ward of government medical college, Kozhikode from January 1, 2014 to December 31, 2014 with probable or definite DRESS as per the RegiSCAR scoring system and who were willing to undergo skin biopsy were included in this prospective study.<bold>Results: </bold>The study population comprised of nine patients. The consistent histological finding documented was the predominantly lymphocytic dermal inflammatory infiltrate. Four of the five patients whose histology revealed focal interface dermatitis and keratinocyte vacuolation with or without apoptotic keratinocytes, had elevated liver transaminases. Tissue eosinophilia was associated with disease flares. The presence of atypical lymphocytes in peripheral smear and histological evidence of dense dermal inflammatory infiltrate showed an association with hepatic involvement.<bold>Limitations: </bold>The main limitations of our study were the small sample size and our inability to carry out a detailed immunohistochemistry work-up.<bold>Conclusions: </bold>In the appropriate setting, varying combinations of epidermal hyperplasia, spongiosis, parakeratosis and individually necrotic keratinocytes in the background of lymphocyte predominant dermal infiltrate (with some atypia) favor a diagnosis of drug reaction with eosinophilia and systemic symptoms. Female sex, the presence of atypical lymphocytes in peripheral smear, dense dermal inflammatory infiltrate, tissue eosinophilia and interface dermatitis with or without keratinocyte necrosis was associated with a poor prognosis. [ABSTRACT FROM AUTHOR]