The hypereosinophilic syndrome(HES) represents a leukoproliferative process likely caused by a number of disorders, all of which are marked by sustained over-production of eosinophils.

The purposes of this study were aimed at evaluating the clinical and histopathological characteristics of HES.

The medical records and hist opathological slides of patients with HES who had skin biopsies performed in our department were reviewed. Criteria for the diagnosis of HES include (1) peripheral blood eosinophilia with eosinophil counts greater than 1,500/L for at least 6 months; (2) no evidence of parasitic, allergic, or other known causes of eosinophilia; and (3) presumptive signs and symptoms of multiple organ involvement.

Four male and three female patients were included. HES developed in adulthood or old age (mean, 43.4 years). Because only the patients with cutaneous involvement were included, all the patients showed skin lesions. Heart, liver, stomach, nervous system, lymph nodes, and lung were involved organs in decreasing order of frequency. At the onset of HES, 40 to 80% of white blood cells were eosinophils in peripheral blood. White blood cell count and serum IgE level were elevated in all the tested patients. In six patients (85.7%), the level of serum erythrocyte sedimentation rate was elevated. Persistent hypereosinophilia (>1,500/L) was present for longer than 6 months in all patients. Stool examination and skin test for parasitic infestation all gave negative results. All the patients were not taking any medication. Histopathological examinations revealed perivascular mixed inflammatory cell infiltration; predominantly eosinophils in the stomach, liver, and nerve as well as in the skin. Interestingly, two patients who were presented with skin lesions showed the findings of eosinophilic vasculitis. In these patients, the skin lesions were consisted of Raynaud's phenomenon, digital gangrene, and several erythematous plaques. The most common cutaneous manifestations were papules and nodules on the extremities. The main treatment modality was systemic steroid. Except for one patient presented with central nervous system involvement of HES, all the patients were in a well-controlled state. In one patient with the typical clinical and hematologic features of HES, Hodgkin's disease followed. After the complete remission of Hodgkin's disease with chemotherapy, HES subsided.

HES is a heterogenous collection of disorders marked by hypereosinophilia and organ damage. Most common cutaneous manifestations were papules and nodules on the extremities. Raynaud's phenomenon and digital gangrene can be the primary manifestation of HES in which cases cutaneous lesions showed eosinophilic vasculitis. Five patients (71%) responded well to systemic steroids. HES may be a herald of malignancy such as Hodgkin's disease. Further investigation will be mandatory ro elucidate the etiology and pathogenesis of HES.