Cutaneous myelofibrosis

Cutaneous extramedullary hematopoiesis is rare, usually occurring in ueonates following intrauterine viral infections, hereditary spherocytosis or the twin transfusion syndrome. Only 20 cases of cutaneous extramedullary hematopoiesis have been reported in adults, all with myelofibrosis. The cutaneous inliltrates may be atypical and difficult to distinguish from leukemia cutis. We have studied a 65‐year‐old woman with myelofibrosis and approximately 40 violaceous, firm, non‐tender cutaneous nodules measuring 1 to 4 cm in diameter, located on her abdomen near a splenectomy scar. Histologically, the lesions had a dense infiltrate of myeloid cells in all stages of maturation, atypical large cells with multilobate nuclei or multiple nuclei, resembling atypical megakaryocytes, and fibroblasts. Although the patient received erythropoietin therapy prior to the development of the nodules, erythroid progenitors were not seen. Reticulin was increased particularly surrounding the atypical megakaryocytes. The myeloid cells stained for chloracetate esterase and with the polyclonal antibody MAC 387. Atypical megakaryocytes stained for Factor Xllla and Factor Vlll‐related antigen. Dendritic Factor XIIla positive cells were also increased. The skin lesions remain unchanged grossly one year after their development. Hoss DM, McNutt NS. Cutaneous myelofibrosis.