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Eosinophilic vasculitis as a manifestation of idiopathic hypereosinophilic syndrome

Dear Editor, Hypereosinophilic syndrome (HES) is characterized by peripheral eosinophilia (eosinophils, ≥1500/μL), eosinophilassociated endorgan damage, and no underlying causative disorders such as infections, allergic diseases, bullous diseases (e.g., bullous pemphigoid), pulmonary diseases, malignant neoplasms, and collagen diseases including eosinophilic granulomatosis with polyangiitis (EGPA).1– 4 We present the very rare case of a Japanese patient with eosinophilic vasculitis (EoV) as a cutaneous manifestation of idiopathic HES. A man in his 70s presented with a 1month history of multiple purpura of the trunk and extremities, and edema of the upper eyelids. Oral antihistamines and tranexamic acid showed no efficacy. He was referred to our hospital because of the refractory clinical course. He had no exposure to causative drugs and no medical history of asthma or allergic rhinitis. Physical examination revealed multiple annular palpable purpura on the trunk and extremities, and prominent edema of the upper eyelids and earlobes (Figure 1a,b). No systemic symptoms including fever, arthralgia or peripheral neuralgia were observed. Complete blood counts showed marked eosinophilia of 7223/μL (normal, 70– 450). Testing for antineutrophil cytoplasmic antibody (ANCA), cryoglobulin, and tuberculosis yielded negative results. Serum interleukin5 level was within the normal range (<4 pg/mL). No FIP1L1PDGFRA fusion gene was detected. Serology showed negative results for HIV, hepatic B virus, and hepatic C virus. No clonal Tcell receptor gene rearrangement was detected from peripheral blood mononuclear cells. Bone marrow examination showed normal blood cell counts with no cellular atypia. A biopsy specimen from an annular purpura showed marked perivascular eosinophilic infiltrates and degeneration of vessel walls with red cell extravasation in the dermis, suggesting EoV (Figure 1c– e). No granuloma formation was observed. His electrocardiogram demonstrated sinus rhythm with firstdegree atrioventricular block. No causative disorders including active infection or visceral malignancy were detected from wholebody computed tomography and fecal parasite tests. EoV was diagnosed as a cutaneous manifestation of idiopathic HES. Oral prednisone was started at 60 mg/day (1 mg/kg/day), with rapid beneficial effects. When the dose of prednisone was reduced to 8 mg/day, eosinophil counts again increased from 128 to 2065/ μL, and the rash flared up. We therefore increased the dose of prednisone to 30 mg/day, resulting in rapid efficacy. Prednisone was again tapered. Seven months after starting treatment, we added cyclosporin A at 200 mg/day. Currently, 4 months after adding cyclosporin, the patient is receiving oral prednisone at 6 mg/day and cyclosporin A at 200 mg/day without any symptoms associated with HES. After treatment, neither scar nor infiltration was observed.