Myelofibrosis in severe combined immunodeficiency due to vitamin D deficiency rickets.

An infant with severe combined immunodeficiency is described in whom a refractory anemia and thrombocytopenia developed after the age of 6 months, associated with poor growth and frequent episodes of upper respiratory tract infections and diarrhea. He required frequent blood and platelet transfusions. Bone marrow biopsy provided evidence that the anemia and thrombocytopenia were the results of myelofibrosis which was secondary to vitamin D deficiency. Therapy with 1,25-dihydroxycholecalciferol resulted in resolution of the hematologic and skeletal abnormalities, but he remained susceptible to recurrent serious infections and died at the age of 13 months.