Rapid Improvement of Refractory Cutaneous Hypereosinophilic Syndrome with Abrocitinib Plus Methylprednisolone: A Case Report.

Hypereosinophilic syndrome (HES) is a rare disorder characterized by persistent eosinophilia and end-organ damage. Cutaneous manifestations are frequently refractory to conventional therapies, including corticosteroids and immunosuppressants, creating a significant clinical challenge. The Janus kinase (JAK)-STAT pathway has been implicated in eosinophil activation and survival, suggesting a potential role for JAK inhibitors in management. In this context, we present the case of a 58-year-old female with a 10-year history of refractory generalized erythema, papules, and severe pruritus progressing to erythroderma with scaling. Previous treatments including antihistamines, tripterygium glycosides, glycyrrhizin, sodium thiosulfate, and topical glucocorticoids had failed. Laboratory investigations revealed leukocytosis with severe hypereosinophilia (peak 8.65×109/L, 52.6% of total WBC), hypoalbuminemia, elevated lactate dehydrogenase, and transaminitis. Skin biopsy demonstrated spongiotic edema and eosinophil-rich perivasculitis. Bone marrow examination confirmed eosinophilic hyperplasia (32.5% eosinophils) without evidence of clonality. Comprehensive parasitic and secondary causes were excluded. Following diagnosis of HES, the patient was initiated on methylprednisolone (40 mg/day) combined with abrocitinib (100 mg/day). Within one week, eosinophil count reduced significantly (1.24×109/L, 7%) with concurrent improvement in liver enzymes. Complete cutaneous remission was achieved at 2-month follow-up, enabling substantial steroid reduction. This case underscores that the combination therapy of abrocitinib and methylprednisolone can offer a promising approach for the HES.