Hair on end appearance is seen in X-ray skull in -

Ans. is 'a' i.e., Thalassemia Bone Changes in Thalassemia 1. Bones become thin and pathological fracture may occur. 2. Massive expansion of the marrow of face and skull produces characteristics facies. 3. Severe maxillary hyperplasia and malocclusion. 4. Prominant widening of diploic spaces with "hair on end appearance" caused by veical trabeculae. 5. Crew-cut appearance ---> striking expansion of hematopoietically active marrow that erodes existing coical bone and induces new bone formation giving rise to crew cut appearance. Causes of "Hair on end appearance" --> Sickle cell anemia, Hereditary spherocytosis, G-6-PD deficiency