Agnogenic myeloid metaplasia in childhood: a report of two cases and efficiency of intravenous high dose methylprednisolone treatment.

Myelofibrosis with myeloid metaplasia, or agnogenic myeloid metaplasia (AMM) is a chronic myeloproliferative disorder characterized by fibrosis of the bone marrow accompanied by aniso- and poikilocytosis, leukoerythroblastosis and hepatosplenomegaly with extramedullary hematopoiesis. Agnogenic myeloid metaplasia is very rare in children. In this report, two cases of AMM in whom the onset of the illness were at 3 and 12 months of age, are presented. Both had severe anemia, hepatosplenomegaly and bone marrow fibrosis. Lymph node biopsy of the first patient and liver biopsy of the second revealed extramedullary hematopoiesis. They were treated with an intravenous high dose of methylprednisolone (daily 30 mg/kg for 3 days, 20 mg/kg for 4 days, 10 mg/kg for 1 week, 5 mg/kg for 1 week). A complete improvement of hematological and clinical findings was observed.