Leukocytoclastic Vasculitis With Eosinophilia in a Patient Receiving Dupilumab Therapy.

We present the case of a patient with a history of treated hepatitis C virus who was diagnosed with prurigo nodularis and subsequently developed leukocytoclastic vasculitis (LCV) with eosinophilia following the initiation of dupilumab therapy. A 69-year-old African American female with previously treated hepatitis C virus presented with a papular, pruritic skin eruption initially diagnosed as prurigo nodularis. Despite treatment with oral and topical corticosteroids, she experienced no improvement. Physical examination revealed numerous hyperpigmented papules on the extensor surfaces of both upper extremities, without blisters or bullae. After starting on dupilumab, she noted minimal improvement and developed new erythematous papules on the right upper extremity. A punch biopsy performed due to ongoing symptoms showed perivascular and interstitial neutrophils with numerous eosinophils, consistent with LCV with eosinophilia. Dupilumab was discontinued, and topical tacrolimus was initiated. One month later, repeat biopsy was consistent with lichen simplex chronicus, suggesting the persistence of a chronic inflammatory state following the resolution of the initial vasculitis.  This patient's findings underscore the importance of recognizing a potential association between dupilumab and the development of eosinophilic conditions in the context of dupilumab therapy. The temporal relationship between the initiation of dupilumab treatment and the onset of eosinophilic LCV suggests a potential association that should be further investigated and should encourage dermatologists to remain cognizant of the development of LCV in the setting of dupilumab therapy.