Myeloproliferative Disorders
This is overproliferation of blood cells and has a tendency to
transform in to acute lekaemia. These conditions tend to affect those
in middle or old age.
Polycythaemia
This is overproliferation of red blood cells.
Classification:
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Apparent (i.e. not really raised)
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Diuretics (decreased blood volume), obesity, hypertensino, smoking
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Primary (polycythaemia rubra vera)
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Raised RBC, WBC and platelets, bright red face.
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Secondary
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Hypoxaemic (compensatory): eg chronic lung disease, cyanotic congenital heart diseaes
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Renal: eg hypernephroma, polycystic ovarian syndrome, renal cell tumour (causing a raised epo level)
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Miscellaneous eg fibroids
Clnical features include facial plethora, headache, mental clouding and
pruritus. The condition is associated with hypertension, splenomegaly,
gout (hyperuricaemia) and bleeding. Occlusive vascular disease, for
example stroke, may develop.
Investigations include:
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Differentiate from apparent: measure red cell mass, plasma volume using radionucleotide labelling of RBCs and albumin
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Serum epo: decreased in primary (negative feedback)
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Jak 2 mutation (mutation in epo rec allows epo independent proliferation)
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Bone marrow biopsy: hyperplasia, fibrosis, Fe deficiency, cytogenetic abns
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Spleen USS
Treatment is repeated venesection to maintain a normal PCV. Hydroxyurea
if thrombocytosis is present. Low dose aspirin to reduce the risk of
vascular events is useful. IV radioactive phosphorus may be given to
reduce bone marrow proliferation of red blood cells however this
treatment is restricted to the elderly because it there is an increased
risk of leukaemia
Essential Thrombocythaemia
This is
excess platelets in the blood. Presentation is with microvascular
occlusive events, such as erythromelalgia (burning pain in
extremities), or major occlusive events such as stroke. Livedo
reticularis is a red marbling rash which is associated with the
condition.
Investigations:
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Blood film: increased platelets
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Bone marrow: increased megakaryocytes
Treatment is with low dose aspirin to reduce occlusive events. Hydroxyurea reduces the number of platelets in the blood.
Myelofibrosis
In this condition the bone marrow is replaced by fibrous tissue. and
thus production of red and white cells is reduced. It occurs in middle
aged/elderly people usually. Patients may present with massive
splenomegaly, symptoms of anaemia, weight loss, bleeding and cachexia.
Investigations reveal:
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Anaemia
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"Marble bone" (increased density) on XR
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Blood film: leukoerythroblastic picture (leukoblasts, myelocytes), tear drop cells
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Bone marrow: abnormal megakaryocytes, increased fibrous tissue