Eosinophilic dermatosis of hematologic malignancy: Correlation of molecular characteristics of skin lesions and extracutaneous manifestations of hematologic malignancy

Background Skin diseases are frequent in patients with chronic lymphocytic leukemia (CLL) and other hematological neoplasias. Eosinophilic dermatosis (ED) of hematologic malignancy has long been considered a nonspecific cutaneous reaction pattern. Recently neoplastic cells have been shown to be present in ED, thus challenging the classification as a nonspecific dermatosis. Methods We report five patients with ED in association with CLL. We further investigated the presence of neoplastic B‐cells in the skin infiltrate by immunohistochemistry and immunoglobulin heavy chain rearrangement and compared these to extracutaneous manifestations of CLL. Results The phenotype of the lymphocytic infiltrate was predominately CD3+ (range: 60%‐90%). CD20+ and CD79a+ lymphocytes were less frequent, accounting for up to 15% (range: absent ‐ 15%). CD23+ lymphocytes represented up to 20% (range: absent ‐ 20%) of the infiltrate. The analysis of the immunoglobulin heavy chain rearrangement in the skin specimens showed clonal rearrangements in 4/5 patients and in three of these four patients clones were identical to extracutaneous CLL manifestations. Conclusion Our data show that neoplastic B‐cells are very frequently found in ED when systematically evaluated. This findings support the hypothesis that leukemic cells play a pathogenetic role in ED of hematologic malignancy.