Overview

• a myeloproliferative disorder
• thought to be caused by hyperplasia of abnormal megakaryocytes
• the resultant release of platelet derived growth factor is thought to stimulate fibroblasts
• haematopoiesis develops in the liver and spleen

PC

• e.g. elderly person with symptoms of anaemia e.g. fatigue (the most common presenting symptom)
• massive splenomegaly
• hypermetabolic symptoms: weight loss, night sweats etc

Investigations

• anaemia
• high WBC and platelet count early in the disease
• 'tear-drop' poikilocytes, nucleated RBCs on blood film
• unobtainable bone marrow biopsy due to the fibrotic state of the bone marrow- 'dry tap' therefore trephine biopsy needed
• high urate and LDH (reflect increased cell turnover)
• Cytogenetic and molecular analysis - shows the absence of the Philadelphia chromosome (BCR-ABL fusion gene); this helps to distinguish myelofibrosis from CML.
  • A JAK2 mutation is present in approximately 60% of cases and a CALR mutation in 25%.

Management