Histopathology of the Exanthema in DRESS Is Not Specific but May Indicate Severity of Systemic Involvement

OBJECTIVE Exanthema in drug reaction with eosinophilia and systemic symptoms (DRESS) has no specific clinical diagnostic hallmark and there are few histopathologic studies. The aim of this study was to describe dermal-epidermal histopathologic features in DRESS and correlate them with the culprit drug, viral reactivation, or systemic organ involvement. METHODS Skin biopsies were independently evaluated by 2 dermatopathologists who characterized the main histological patterns and scored dermal and epidermal changes, which were further correlated with clinical and laboratorial data. RESULTS In 15 DRESS patients (9 male/6 female patients, mean age 53.3 years), the main observation was lymphocyte exocytosis (1.87 ± 1.25), spongiosis (0.93 ± 0.94), scattered keratinocyte necrosis (1.70 ± 1.44), basal cell vacuolization (2.13 ± 1.42), lymphocyte infiltration around dermal vessels (2.93 ± 0.92) or at the dermal-epidermal junction (2.07 ± 1.12), often with eosinophils and extravasated erythrocytes, swollen endothelial cells, and intravascular neutrophils but no vasculitis. Histopathologic patterns were classified mainly as spongiotic (5), erythema multiforme-like (3), or lichenoid (2). There was a significant positive correlation between the intensity of lymphocyte infiltration and the severity of hepatic cytolysis (r = 0.51; P < 0.05) and eosinophilia (r = 0.51; P < 0.05). No correlation was observed between the intensity and type of dermal inflammation and the degree of epidermal damage or the culprit drug. Human herpes virus type 6-positive patients had a pseudolymphomatous reaction or a perifollicular localization of the infiltrate. CONCLUSIONS Histopathology in DRESS is variable with no specific diagnostic aspect, but there is a possible correlation between the intensity of the lymphocyte infiltrate and DRESS severity, namely, liver cytolysis.