Unusual extramedullary hematopoiesis in a patient receiving granulocyte colony-stimulating factor.

A 42-year-old woman was diagnosed with myelodysplastic syndrome with fibrosis that developed bilaterally, cervical lymphadenopathy and cutaneous infiltration by trilineage extramedullary hematopoiesis after granulocyte colony-stimulating factor therapy because of severe neutropenia. Hepatosplenomegaly was not observed during her follow-up. Extramedullary hematopoiesis disappeared after growth factor therapy was stopped. Although the neutropenia was alleviated by growth factor administration, the appearance of an unusual involvement of extramedullary hematopoiesis should be kept in mind.