[Eosinophilic dermatosis associated with hematological disorders: A clinical, histopathological and immunohistochemical study of six observations]

Eosinophilic dermatosis of hematologic disease (EDH) or insect bite-like reaction is a pruritic dermatitis described mostly in patients with chronic lymphocytic leukaemia (CLL). We describe six patients with the disorder in association with CLL and other blood dyscrasias.We reviewed the medical records of patients with EDH seen between 2004 and 2009 in our department and re-examined histological slides.Mean age at dermatosis onset was 75.6 years and the sex ratio was 1. There were three CLL, two mantle-cell lymphomas and one MALT-type lymphoma. The dermatitis was quite polymorphic, with erythematous papules, wheals and plaques. The initial skin lesions appeared at the same time as or after the diagnosis of haematological neoplasm. Their reappearance heralded relapse of the blood disease in three cases. Histologically, all lesions had a dense dermal infiltrate of small, mostly CD4+ T-cells, with numerous eosinophils. In three patients, there was marked folliculotropism, resembling folliculotropic T-cell lymphoma. In most cases, EDH disappeared after appropriate chemotherapy for the blood disorder.Our cases show that the clinical expression of EDH is quite polymorphic. Its appearance may precede relapse of or may indicate prompt search screening for blood dyscrasia. The most efficient treatment of this dermatosis appears to be specific chemotherapy for the blood dyscrasia. There is reason to believe that a population of T-helper 2 (Th2) lymphocytes, reactive to malignant B-cells, induces tissue eosinophilia, mainly through production of interleukin (IL)-5, among other cytokines. Eosinophils appear to be the main effector cells.