A 10-year-old child from a Mediterranean family has hemoglobin of 6.5 g/dL, splenomegaly, facial bossing, and hemoglobin electrophoresis showing HbA absent, HbF 92%, HbA2 8%. What is the pathophysiology of facial bossing in this condition?

• A Iron overload causing calcium-iron deposits in facial bones
• B Recurrent vaso-occlusive crises causing avascular necrosis of facial bones
• C Secondary hyperparathyroidism causing resorption of cortical bone
• D Extramedullary hematopoiesis and marrow hyperplasia expanding medullary cavities of skull ✓

Explanation

This is beta-thalassemia major (Cooley anemia). Absent HbA, predominant HbF with elevated HbA2 confirms homozygous beta-thalassemia. Ineffective erythropoiesis drives intense erythroid marrow hyperplasia; medullary expansion of skull diploë and facial bones causes the characteristic 'hair-on-end' skull X-ray appearance and facial bossing. Splenomegaly results from extramedullary hematopoiesis. Iron overload is a consequence of transfusions and increased absorption but does not cause bossing.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.