Extramedullary hemopoiesis of the skin.

The skin is a potential site for extramedullary hemopoiesis since hemopoiesis occurs in the skin in early embryonic life. However, a review of the English literature reveals only five reported cases of extramedullary hemopoiesis of the skin. 1-4 All of these patients suffered from myelofibrosis. I report herein another case of myelofibrosis associated with papulonodular and plaque-like lesions of the skin that microscopically exhibited extramedullary hemopoiesis. Report of a Case A 64-year-old man with fever of unknown origin that had been present for 14 months was admitted to the Veterans Administration Medical Center, New Orleans, in March 1974. Physical examination showed a nontender, palpable liver, 5 cm below the right costal margin, and a palpable spleen, 3 cm below the left costal margin. There was no lymphadenopathy. Hematologic studies indicated the following values: hemoglobin, 9.1 g/ dL; hematocrit, 31.7%; RBCs, 3,900,000/cu mm; WBC, 8,300/cu mm; differential cell count, normal; and