Necrotizing leukocytoclastic small vessel vasculitis associated with letrozole: A case report

Abstract

Introduction: Letrozole is an aromatase inhibitor that used to treat breast cancers. Letrozole-associated skin vasculitis is a rare side effect of this medication, in this study we report a case of necrotizing type of Small vessel cutaneous vasculitis associated with letrozole consumption. Case presentation: A 45-year-old woman was referred to the dermatology clinic with painful necrotic annular lesions on the lower limbs. Her past medical history showed evidence of breast cancer and taking letrozole. Five months after the start of letrozole, the patient's signs and symptoms had appeared. Physical examination revealed annular plaques with erythematous margin and multiple necrotic centers that were painful to touch. The histopathology showed extravasated red blood cells and leukocytoclasis as well as neutrophils surrounding and infiltrating the wall of blood vessels in superficial and mid dennis. We discontinued letrozole, then prescribed topical clobetasol, systemic prednisolone, and colchicine; the lesions began to heal after 1 month from the start of treatment, and did not recur after discontinuing the treatment. Discussion: Pathogenesis of vasculitis caused by aromatase inhibitors is not fully elucidated, but estrogen depletion and idiosyncratic drug reaction has been proposed. Cutaneous leukocytoclastic small vessel vasculitis (CLSVV) resulting from aromatase inhibitors is relatively rare so it is recommended to consider drug-induced CLSVV in other patients treated with aromatase inhibitors.