Myelofibrosis arising in treated histiocytosis X

Myelofibrosis, or fibrous replacement of hematopoietic bone marrow, is rarely encountered in pediatric patients. An unusual, reversible case arising in the setting of treated histiocytosis X is reported, a previously undescribed association. The clinical, pathologic, radiographic, and scintigraphic characteristics of myelofibrosis are reviewed.