IMAGE OF THE WEEK

WEEK 37

 

THALASSAEMIA

 

 

 

  

Figure 1

 

 

 

 

What is Thalassemia?

Thalassemia is a spectrum of genetic disorders of haemoglobin synthesis typically seen in individuals of Mediterranean descent. There is an underproduction of either alpha chains (thus it is called ‘alpha-thalassemia’) or underproduction of beta chains of haemoglobin molecule (‘beta-thalassemia’). Beta-thalassemia is then categorized into 3 types:

1.   Thalassemia Major (Cooley’s anaemia)

A homozygous defect of both β-globin genes. This typically presents within the first 2 years of life with growth retardation, hypochromic microcytic anaemia, bleeding diathesis, susceptibility to infection, elevated bilirubin, hyperpigmentation of skin and hyperuricemia.

2.   Thalssemia Intermedia 

A subgroup of homozygous form, with a milder presentation.

3.   Thalassemia Minor or Trait

A heterozygous defect in one β-globin gene. Usually asymptomatic, except for periods of stress. Occasionally the patient will become jaundiced and may have splenomegaly

 

RADIOLOGY

Lateral skull x-ray in Thalassemia Major

There is gross thickening of the diploe of the skull (Figure 1). This results from marrow hyperplasia from extramedullary haematopoiesis (production of RBCs outside the bone marrow) as a response to anaemia.

Extramedullary haemopoiesis may occur elsewhere in the body in thalassemia. See Image of the Week 30.

This can also result in ‘frontal bossing’ of the skull - an unusually prominent forehead.

In its most extreme form the skull shows bony spiculation, described as having a ‘hair on end’ appearance.

See http://radiology.rsna.org/content/221/2/347.full

There may also be underpneumatisation of the paranasal sinuses.

 

Figure 2

 

Figure 2: Lateral skull x-ray in Thalassemia Major. Arrows indicate the thickness of diploe. The diploe is the cancellous bony tissue between the external and internal tables of the skull. Stars indicate the frontal bossing.

 

 

Images contributed and prepared by

Diyana Mohamed, 6th year medical student, The University of Queensland

& Dr Ian Bickle, Consultant Radiologist, RIPAS Hospital, Brunei

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All images are copyrighted and property of RIPAS Hospital.

 

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