Lymphocyte-variant hypereosinophilia involves eosinophilia triggered by cytokines released from T-cells, which may show (a) a clonal proliferation or (b) reactive change to a chronic process.
The patient may present with:
(1) cutaneous lesions
(2) lesions in other organs
(3) an elevated eosinophil count (usually an absolute eosinophil count >= 1,500 per µmL)
(4) an elevated serum IgE concentration
The initial evaluation shows that the eosinophilia:
(1) is not reactive to usual causes
(2) is associated with bone marrow cells negative for specific mutations by molecular studies (PDGFRA, PDGFRB, FGFR1)
Testing shows T-cells with an abnormalimmunophenotype with one of the following:
(1) CD3 positive, CD4 negative, CD8 negative (double negative)
(2) CD3 negative, CD4 positive
Variable findings may include:
(1) clonal rearrangement of T-cell receptor gene
(2) loss of surface CD7
(3) expression of CD27
Further testing may show:
(1) in vitro Th2 cytokine profile (IL-5, IL-4, IL-13) from cultured peripheral blood T-cells
(2) elevated serum levels of TARC (thymus and activation regulated chemokine)
