Chronic eosinophilic leukemia complicated by epidural myeloblastoma

Epidural myeloblastoma, which compressed the spinal cord, was the first evidence for chronic granulocytic leukemia, eosinophilic type, Ph chromosome negative. This manifestation was preceded by 3 years follow-up of a patient with persistent eosinophilia of 60% mature eosinophils. The only clues for the diagnosis of leukemia were splenomegaly and high serum vitamin B12, most of which was bound to transcobalamin I. The latter finding presents a useful diagnostic criterium in myeloproliferative disorders.