'Hair on end' appearance in skull X-ray is characteristic of:

Ans. (b) Sickle cell anemia* Hair on end appearance of the skull is a characteristic feature of chronic haemolysis usually seen in patients with thalassemia and sickle cell anaemia. It results from accentuated vertical trabeculae between the inner and outer tables of the skull because of excessive bone marrow hyperplasia.Conditions where 'Hair on End Appearance' is seen: Mne- monic: HI NEST* Hereditary spherocytosis* Neuroblastoma* Enzyme deficiency (e.g. G-6-P deficiency causing haemolytic anaemia)* Sickle cell disease* Thalassemia major