Histopathology of drug rash with eosinophilia and systemic symptoms syndrome: a morphological and phenotypical study.

BACKGROUND: The histopathological features of drug rash with eosinophilia and systemic symptoms (DRESS) syndrome remain poorly characterized.

OBJECTIVES: To better characterize the histopathological features of DRESS syndrome, and define the phenotype of the effector cells in the skin and compare it with maculopapular rash (MPR).

METHODS: We conducted a retrospective study on 50 skin biopsies from patients with DRESS syndrome (n = 36). Histopathological and immunophenotypical features were studied and compared with a series of MPRs (n = 20).

RESULTS: Foci of interface dermatitis, involving cutaneous adnexae, were frequently seen in cases of DRESS. Eosinophils were seen in only 20% of cases and neutrophils in 42%. Eczematous (40%), interface dermatitis (74%), acute generalized exanthematic pustulosis-like (20%) and erythema multiforme-like (24%) patterns were observed. The association of two or three of these patterns in a single biopsy was significantly more frequent in cases of DRESS than in a series of nondrug-induced dermatoses (P < 0.01), and appeared to be more marked in DRESS syndrome with severe cutaneous lesions (P = 0.01) than in less severe cases of DRESS and MPR. A higher proportion of CD8(+) and granzyme B(+) lymphocytes was observed in cases of DRESS with severe cutaneous eruptions (erythroderma and/or bullae). Atypical lymphocytes were found in 28% of biopsies, and expressed CD8 in most cases; a cutaneous T-cell clone was rarely found (6%).

CONCLUSIONS: The histopathology of DRESS syndrome highlights various associated inflammatory patterns in a single biopsy. Cutaneous effector lymphocytes comprise a high proportion of polyclonal CD8(+) granzyme B(+) T lymphocytes.