Myelofibrosis

Myelofibrosis

Definition

A myeloproliferative disorder characterised by an increase in reticulin and collagen in the marrow cavity.

Prevalence

2 per 1,000,000 population.

Age

Most commonly diagnosed 60–70 years.

Sex

M = F

Aetiology

Increased risk following exposure to benzene or radi-ation. Myelofibrosis may develop late in the course of polycythaemia vera or essential polycythaemia.

Pathophysiology

Myelofibrosis is characterised by proliferation of fibroblasts in the marrow as a response to growth factors secreted by abnormally proliferating myeloid cells. As the bone marrow cavity becomes fibrotic, extramedullary haematopoiesis occurs in the liver and spleen causing hepatosplenomegaly.

Clinical features

Patients may present with symptoms of anaemia, anorexia, weight loss, and night sweats. On examination there is massive splenomegaly. Symptoms and signs of marrow failure (anaemia, recurrent infections and bleeding) may be present.

Investigations

A blood film shows a leucoerythroblastic anaemia with teardrop poikilocytes, nucleated red blood cells and immature myeloid elements. Marrow aspiration is normally impossible, the trephine shows dense fibrosis.

Management

Symptomatic management with red blood cells and platelet transfusions and haemopoetic growth factors. Iron chelation therapy may be required if multiple transfusions are necessary.

Splenectomy may be required if the enlarged spleen is painful or to reduce transfusion requirements.

Prognosis

The median survival of patients with myelofibrosis is 3–6 years. Ten to twenty per cent of patients develop acute myeloid leukaemia.