Conditions associated with extramedullary proliferation of normal marrow elements:
(1) administration of myeloid growth (colony stimulating) factors or release of cytokines
(2) severe anemia
(2a) thalassemia
(2b) sickle cell anemia
(2c) hereditary spherocytosis
(2d) congenital dyserythropoietic anemia
(3) myeloproliferative-myelodysplastic syndrome
(3a) myelofibrosis with myeloid metaplasia
(3b) polycythemia rubra vera
(3c) chronic myeloid leukemia
(3d) myelodysplastic syndrome
(4) immune thrombocytopenic purpura (ITP)
(5) bone diseases with compression on the medullary spaces
(5a) Paget's disease of bone
(5b) osteopetrosis
(6) infiltrative disorders of the bone marrow
(6a) Gaucher's disease
(7) idiopathic
