<scp>CD30</scp>+ clonal T‐cell lymphoid proliferation of the skin in a patient with hypereosinophilic syndrome

We report a hitherto undescribed unusual CD30+ clonal T-cell proliferation in a 46-year-old man with the lymphocytic variant of hypereosinophilic syndrome with a 17-year history of pruritus, generalized persistent papulonodular skin lesions and peripheral blood hypereosinophilia. A skin biopsy showed an eosinophil-rich infiltrate with small to medium-sized CD30+ lymphocytes and Churg-Strauss granulomas. Peripheral blood flow cytometry revealed an aberrant T-cell clone which, molecular genetically, was identical to the T-cell clone detected in the skin. No genetic aberrations of platelet-derived growth factor receptor alpha (PDGFRA), FIP1L1-PDGFRA, PDGFRB or FGFR1 were found. The skin lesions showed transient response to systemic and topical corticosteroids. The skin lesions represent cutaneous involvement by clonal T-cells in hypereosinophilic syndrome and differ from known cutaneous CD30+ lymphoproliferative disorders.