Table 3 Causes of grade 4 bone marrow fibrosis (diffuse, often coarse reticulin fibre network with areas of collagenization)

I. Generalized myelofibrosis:

Neoplastic / Clonal disorders

Chronic idiopathic myelofibrosis* (myelofibrosis with myeloid metaplasia; also known as agnogenic myeloid metaplasia)

Myelofibrosis secondary to essential thrombocythaemia or polycythaemia rubra vera*

Chronic myeloid leukaemia*

Acute megakaryoblastic leukaemia*

Other acute myeloid leukaemias

Acute lymphoblastic leukaemia

Systemic mastocytosis*

Myelodysplastic syndromes (particularly secondary MDS)

Myelofibrotic myelodysplastic syndrome (Pagliucaet al, 1989)

Acute panmyelosis with myelofibrosis

Paroxysmal nocturnal haemoglobinuria

Hodgkin lymphoma

Non-Hodgkin lymphoma

Plasma cell myeloma

Metastatic tumours

Bone and connective tissue diseases*

 Osteopetrosis

 Primary and secondary hyperparathyroidism

 Nutritional and renal rickets (vitamin D deficiency)

 Osteomalacia

 Primary hypertrophic osteoarthropathy

 Pachydermoperiostosis

 Miscellaneous conditions

 Tuberculosis

  Other granulomatous diseases

  Grey platelet syndrome

  Systemic lupus erythematosus

  Systemic sclerosis

  Sjogren syndrome

  Primary autoimmune myelofibrosis

   Antiphospholipid antibodies

  Other autoimmune myelofibrosis

   Prior thorium dioxide administration

  II. Focal or localized fibrosis

   Osteomyelitis

   Paget’s disease

   Following bone marrow necrosis

   Following irradiation of the bone marrow

   Adult T-cell leukaemia/lymphoma

   Healing fractureSite of previous trephine biopsy*