The radiological appearances of thalassaemia.

The skeletal changes of untreated thalassaemia result from ineffective erythropoiesis and expansion of the bone marrow and affect every part of the skeleton. These changes include osteoporosis, growth retardation, platyspondyly and kyphosis. Erythropoiesis occurs at extra-medullary sites, most commonly resulting in a paraspinal mass but occasionally affecting organs containing pluripotential stem cells. Repeated transfusion unaccompanied by iron chelation causes haemosiderosis; iron is deposited at various sites causing functional impairment. Iron-chelation therapy with desferrioxamine (DFX) prevents haemosiderosis but causes a skeletal dysplasia predominantly affecting the rapidly growing long bones, in particular the distal ulna, and causing irregularity and sclerosis of the physeal-metaphyseal junction and splaying of the metaphysis. DFX also exacerbates the observed growth retardation. DFX-induced skeletal dysplasia may herald toxicity, which is associated with visual and auditory impairment. Therefore, careful balancing of the transfusion regimen and iron-chelation therapy is required. Magnetic resonance imaging (MRI) is the most sensitive technique for the detection of DFX-induced dysplasia.