A Lymphocytic Variant of Hypereosinophilic Syndrome Presenting With Isolated Cutaneous Manifestations.

Hypereosinophilic syndrome (HES) is a rare disease defined by a persistent increase in eosinophilic cells associated with organ damage without any underlying cause. Three variants have been identified: myeloproliferative, lymphocytic, and idiopathic syndrome. The symptomatology is variable because it depends on the involvement of different organs, including the circulatory system, skin, lungs, digestive tract, peripheral and central nervous system, and eyes. Although cutaneous involvement may frequently reveal an underlying HES. We report a case of a 52-year-old man with a 12-year history of skin lesions with intense pruritus. On examination, the patient presented with erythroderma, extensive infiltrated plaques, excoriated itchy papules, palmoplantar pustules, ear infiltration, periorbital edema, and cutaneous xerosis. Histopathology showed lichenoid dermatitis without epidermotropism. Inflammatory infiltrates in the dermis were principally composed of eosinophilic cells and lymphocytes. Serum immunoglobulin E and peripheral blood immunophenotyping showed atypical T lymphocyte proliferation CD4+CD3-, and clonal TCR gene rearrangement was in favor of lymphocytic HES. The patient was treated with prednisone (1 mg/kg/day) and pegylated interferon alpha with improvement. This case shows that HES should be suspected in patients with dermatological lesions and hypereosinophilia, without obvious cause. Elimination of secondary causes of eosinophilia, evaluation of deep organ involvement, and cytogenetic studies to assess prognosis are paramount. Pegylated interferon alpha 2a may be an effective treatment option for steroid-resistant or refractory patients with lymphocytic HES.