Myelofibrosis with myeloid metaplasia in adult individuals 30 years old or younger: presenting features, evolution and survival.

Myelofibrosis with myeloid metaplasia (MMM) usually affects older people and is associated with a median survival of 3.5-5 yr. Survival of MMM patients 55 yr old or younger is longer, but there is no information on the youngest subset. The presenting features, evolution and survival were analyzed in 9 patients with MMM aged 30 yr or less, representing 2.8% of two series including 323 cases. Age ranged from 17 to 30 yr; 3 patients were males and 6 females. Five patients were asymptomatic and none had constitutional symptoms. Anemia was observed in 4 patients, being severe in only one. The WBC count was normal in 7 patients and 2 had mild leukocytosis; moderate thrombocytosis was observed in 7 patients. No patient showed blood blast cells or bone marrow cytogenetic abnormalities. With a median follow-up of 6.8 (range 0.8-28) yr, 2 patients died 10.7 and 9.9 yr from diagnosis, one from complications of bone marrow transplantation performed after progression of the disease and the other from gastrointestinal bleeding secondary to portal hypertension. Among remaining patients, one developed Budd-Chiari syndrome, another was lost to follow-up at 3 yr, and 5 remain asymptomatic and currently without treatment (one had been splenectomized at diagnosis). These results indicate that in most young adults with MMM the disease presents without adverse prognostic factors and may remain stable for years, which may be of interest when considering the treatment of such patients.