[Primary myelofibrosis with positive coombs' test responding to prednisolone].

Primary myelofibrosis was diagnosed in a 43-year-old female in 1991, who gradually became transfusion dependent. There was no evidence suggesting connective tissue diseases except for biological false positive STS. Because her direct Coombs' test was positive and serum haptoglobin level was extremely low (< 6mg/dl), intermediate dose (30mg/day) prednisolone therapy was started. Her hemoglobin level and platelet count increased dramatically to a normal level within 3 weeks after the initiation of prednisolone therapy. Bone marrow biopsy performed 6 months later revealed marked recovery of hematopoiesis. Though the effects of corticosteroid therapy in primary myelofibrosis still remain unclear, this therapy might be useful in the treatment of some groups of patients via the correction of immunological aberrations and/or the decrease of bone marrow fiber.