IS Case 63: Thalassemia
Imaging Sciences URMC 2008
Publication Date: 2009-05-19
Left Hand X-Ray: There is marked expansion of cortices with squared metaphyses and decreased tubulation. By comparison with the Radiographic Atlas of Development of the Hand by Greulich and Pyle, the patient's skeletal age is at the lower limits of normal for the patient's chronologic age.
AP and Lateral Chest X-ray: There is borderline cardiomegaly, prominently involving the right side of the heart. Hila, pulmonary vasculature, lungs and pleural spaces are normal. There is generalized osteopenia, best seen in the humerus and scapula.
Thalassemia major is a severe anemia that typically presents during the first few months after birth. Severe anemia leads to pallor, icterus, cardiac enlargement, development of extramedullary hematopoiesis and bone marrow expansion. Extramedullary hematopoiesis may result in hepatosplenomegaly and soft tissue masses in the posterior mediastinum and pelvis. Marrow expansion leads to characteristic changes in the axial and appendicular skeleton.
Premature fusion of the epiphyses is a characteristic finding in thalassemia. This most commonly affects the proximal humerus, and less frequently in the distal femur, proximal tibia, and proximal femur. The fusion is associated with a variable degree of shortening and is frequently eccentric, leading to angulation of the prematurely fused epiphyses (i.e. varus deformity in the humerus).
Chest x-rays typically show changes in the ribs, due to the varied response of the medulla, cortex, and periosteum to proliferating marrow. Ribs are widened as the marrow expands, especially in the posterior where there is more red marrow. A subcortical lucency may be seen from erosion of the inner aspect of the cortex and adjacent medullary trabeculae by the leading edge of proliferating marrow. This has been termed the "rib-within-a-rib" appearance. There is generalized osteopenia from cortical and trabecular thinning as the marrow expands.
In the skull and facial bones (not included here), widening of the diploic space with a thinning of the tables occurs, frequently with complete obliteration of the outer table. New bone may form beneath the periosteum in response to marrow proliferation and result in a classic "hair-on-end" appearance.
- Blinkman H. Pediatric Radiology: The Requisites, 2nd ed., Mosby, 2008: 96.
- Yaish HM. Thalassemia. E-medicine, August 6, 2007. www.emedicine.com/ped/topic2229.htm