Transforming growth factor–β overexpression in cutaneous extramedullary hematopoiesis of a patient with myelodysplastic syndrome associated with myelofibrosis

Extramedullary hematopoiesis (EMH) is a relatively rare, but well-documented, manifestation of chronic myeloproliferative disorders. Microscopically, foci of EMH consist of erythroid and myeloid precursors intermixed with megakaryocytes. It typically occurs in the spleen and liver, but very occasionally manifests as cutaneous EMH. We report a 76-year-old Japanese man with cutaneous EMH arising from myelodysplastic syndrome associated with myelofibrosis. His cutaneous manifestations showed multiple skin-colored firm nodules over the head, trunk, and extremities. We detected high plasma levels of transforming growth factor (TGF)-β1 in our patient. Immunohistochemical analysis of the skin biopsy sample revealed TGF-β1 overexpression in immature hematopoietic cells and dermal fibroblasts within the cutaneous EMH mass of the dermis. These findings suggest that TGF-β could play some role in the onset of cutaneous EMH. Five months after his first visit to our dermatologic clinic, the patient developed bone-marrow failure and died. Based on our observations, accelerated malignancy in the bone marrow should be considered in any patient with cutaneous EMH. It is presumed that TGF-β released from hematopoietic cells within the cutaneous EMH play a critical role in the activation of hematologic malignancy.