Importance: Generalized eruptive histiocytosis (GEH) is a rare non-Langerhans cell histiocytosis with a benign, self-healing course. Neoplastic hematologic disorders of the myeloid lineage have been reported in association with GEH in 4 patients. A clonal association between GEH and the underlying leukemia was suspected in these patients but could only be confirmed in one patient.
Observations: A male patient in his 20s presented with asymptomatic red to brown macules and papules. A skin biopsy confirmed a diagnosis of GEH. His blood cell count revealed hypereosinophilia. Morphologic and molecular analyses from bone marrow and blood samples revealed FIP1L1-PDGFRA-positive chronic eosinophilic leukemia. The patient was treated with imatinib and achieved complete clinical remission of his leukemia and the GEH.
Conclusions and relevance: To our knowledge, this is the first report of a patient with GEH associated with FIP1L1-PDGFRA-positive chronic eosinophilic leukemia. Generalized eruptive histiocytosis in association with a myeloid neoplasm may occur in 2 variants: a reactive condition or a clonal derivative of the underlying leukemia. In this case, both diseases responded well after initiation of treatment with imatinib.