Intralymphatic CD30+ T-cell proliferation during DRESS: a mimic of intravascular lymphoma.

INTRODUCTION: We describe the case of a patient presenting with drug rash with eosinophilia and systemic symptoms (DRESS), where cutaneous biopsy revealed intravascular atypical lymphocytes suggestive of lymphoma. CASE REPORT: A 77-year-old man was treated with antibiotics for a hip prosthesis infection. Eight weeks later, he developed a maculo-papulous eruption, edema of the extremities, fever and blood eosinophilia. Cutaneous biopsy revealed an atypical T-cell proliferation into the dermal lymphatic vessels. The lymphocytes were mid-sized, with mitoses and apoptotic figures. They were CD3+, CD4+, CD5+ and some were CD30+. There was no T-cell receptor (TcR) clonal rearrangement. Complete regression of cutaneous eruption and eosinophilia was observed after ceasing treatment with antibiotics. The diagnosis was that of a benign atypical intralymphatic T-cell proliferation associated with DRESS. DISCUSSION: The occurrence of atypical dermal CD30+ T-cells in cutaneous biopsy during benign reactive conditions such as arthropod bites or scabies is well-known. The intralymphatic localization of such atypical reactive lymphocytes is much less common and represents a diagnostic pitfall because it can suggest aggressive intravascular lymphoma. CONCLUSION: We report the first case of benign atypical intralymphatic CD30+ T-cell proliferation associated with DRESS. Diagnostic clues include immunohistochemistry, absence of TcR clonal rearrangement, and anatomo-clinical correlation.