Successful treatment of steroid resistant hypereosinophilic syndrome with low-dose CsA
A 41-year-old man visited our emergency room with rashes on both legs and his trunk area.\nOn physical examination, only a skin lesion was found. His complete blood count (CBC) showed hypereosinophilia (eosinophils 4,730/mm3). Although he had no history of allergies, a previous CBC reports showed persistent hypereosinophilia over the previous 6 months.\nSubsequent analyses did not reveal any evidence of secondary HES including any autoimmune disease or parasitic infestation. Bone marrow aspirate and biopsy showed marked eosinophilia without dyspoiesis. FIP1L1-PDGFRA, TEL-PDGFRB, or BCR-ABL rearrangement was not detected on fluorescence in situ hybridization. JAK2 V617F mutation analysis performed with a reverse transcription polymerase chain reaction technique was negative. Serum immunoglobulin E (IgE) level (1,599 mg/dL) and eosinophilic cationic protein level (163.35 ng/mL) were elevated.\nSkin biopsy of the leg rash showed perivascular lymphohistiocytic infiltration and many eosinophils. Flow cytometric analysis to evaluate the associated aberrant T-lymphocyte found no abnormal phenotypes such as CD3-CD4+ or CD3+CD4-CD8-, but the T cell receptor (TCR) gene rearrangement was not checked. Although we could not confirm the subclass of HES, clinical findings indicated a lymphocytic variant of HES (L-HES). The patient initially responded well to a high-dose glucocorticoid treatment, but after reducing prednisone, the eosinophil count and IgE level rebounded. Thus, we administered a low dose of CsA (100 mg bid), and his eosinophil count returned to normal after just 1 week of treatment. Prednisone was then tapered to 10 mg per day ().