Histopathological Features of Bendamustine Extravasation Injury: A Diagnostic Pitfall in an Immunocompromised Patient.

Extravasation of chemotherapeutic agents may lead to a wide spectrum of cutaneous injuries, yet their histopathological features remain poorly characterized, particularly for agents classified as irritants. Bendamustine, a bifunctional alkylating agent widely used in hematologic malignancies, is generally considered an irritant. Histological descriptions of its extravasation-related skin injury are lacking. We report the case of a 77-year-old immunocompromised patient with classical Hodgkin lymphoma who developed persistent cutaneous lesions following suspected bendamustine extravasation. Despite conservative management, the lesion showed an atypical prolonged course, prompting skin biopsy to exclude infection or infiltration by cutaneous lymphoma. Histopathological examination revealed dermal and hypodermal coagulative necrosis, thrombotic phenomena, and minimal inflammatory infiltrate, without evidence of infection or neoplastic infiltration. These findings suggest that bendamustine extravasation may induce deeper tissue injury with prominent vascular involvement, resembling vesicant-related damage rather than a simple irritant reaction. This case highlights a potential diagnostic pitfall in immunocompromised patients and underscores the value of skin biopsy and clinicopathological correlation in suspected chemotherapy extravasation. Our observations challenge the conventional classification of bendamustine as a purely irritant agent and suggest that it may behave as a vesicant under certain conditions.