Laboratory evaluation revealed leukocytosis, with 10%–28% eosinophils, anemia, and an elevated erythrocyte sedimentation rate. Histology findings included hyperkeratosis, irregular acanthosis, and a mixed inflammatory infiltrate of lymphocytes, plasmocytes, and numerous eosinophils. Thrombosis of small vessels in the dermis and edema of the vessel walls was also noted.
Immunohistochemical staining of tissue specimens from this patient revealed the presence of CD43-positive and CD4-positive cells, as well as CD8-negative and CD20-negative lymphocytes.
No cause for her eosinophilia could be identified, despite a meticulous search. Reactive eosinophilia, which can occur with parasitic infections, and clonal disorders of the bone marrow associated with eosinophilia, (e.g., various types of leukemia), were ruled out. The diagnosis therefore was idiopathic hypereosinophilia syndrome.
Some investigators have proposed that idiopathic hypereosinophilia syndrome is a Th2-mediated disease characterized by clonal expansion of a T-cell population able to produce interleukin (IL)-5 and IL-4. Pathogenic T cells—usually CD3 negative, CD4 positive—display an aberrant surface phenotype.
The clinical presentation is heterogeneous and includes myeloproliferative and lymphocytic variants. In the more aggressive myeloid variant, patients can have chromosomal abnormalities, hepatosplenomegaly, cardiac complications, and myeloid malignancies. The prognosis is poor, said Dr. Mira Kadurina of the Military Medical Academy in Sofia, Bulgaria.
The lymphocytic variant may be a primitive lymphoid disorder characterized by nonmalignant expansion of an IL-5-producing T cell population. Cutaneous manifestations can include pruritus, eczema, erythroderma, andurticaria.
She was treated with prednisone, 60 mg/day, which was gradually tapered to 15 mg/day over a month's time. After treatment was withdrawn, she again developed disseminated, erythematous, pruritic lesions, this time involving the hands and feet. The fingers became painful, cyanotic, and swollen, initially after exposure to cold. A painful ulcer appeared on the third finger of the right hand.
Raynaud's phenomenon, identified by capillaroscopy, was an unusual cutaneous complication of the idiopathic hypereosinophilia syndrome in this patient, Dr. Kadurina wrote.
The administration of methylprednisolone, 60 mg/day, and pentoxifylline, 800 mg/day, led to a remission; the corticosteroid dosage was tapered to 5 mg/day over 45 days.
During 3 months of follow-up, no new lesions appeared, the vasoconstriction of the patient's hands disappeared, and the finger ulcer healed.
One explanation for the development of Raynaud's phenomenon and digital gangrene, in association with hypereosinophilia, is that major basic protein and eosinophil cationic proteins located within the eosinophil granule matrix contributed to the formation of microthrombi.
Efforts continue to further explicate the pathogenesis. “Future progress in unveiling variants of the syndrome is likely to consign to history the term idiopathic, replacing it with an array of well-defined hematologic disorders,” Dr. Kadurina wrote.
DR. KADURINA reported this case as a poster at the 14th Congress of the European Academy of Dermatology and Venereology.