Cutaneous extramedullary hematopoiesis in myelofibrosis.

Erythematous papulonodules that resembled a malignant lymphoma developed in a 62-year-old man. Further examination revealed that he had primary myelofibrosis with cutaneous extramedullary hematopoiesis. All three marrow elements (myeloid, erythroid, and megakaryocytic series) were present in the skin lesions. Although extramedullary hematopoiesis of the skin is a rare complication of myelofibrosis, 13 similar cases have been reported. In nine cases, including ours, all three marrow elements were present in the cutaneous lesions.