<aside>
The hair-on-end appearance is a classic radiographic sign seen in skull X-rays, characterized by:
| Cause | Explanation |
|---|---|
| Thalassemia major | Most classic and frequent cause due to severe chronic anemia |
| Sickle cell disease (SCD) | Marrow hyperplasia from chronic hemolytic anemia |
| Hereditary spherocytosis | If anemia is severe and prolonged |
| Congenital dyserythropoietic anemia | Rare inherited forms leading to ineffective erythropoiesis |
| Iron deficiency anemia | Very rarely if chronic and severe |
| Leukemia | Occasionally, from leukemic infiltration and marrow expansion |
| Modality | Findings |
|---|---|
| XR | Expanded diploic space, vertical striations projecting outward from calvarial surface |
| CT | Thickened diploic space, coarse vertical trabeculae |
| MR | May show widened diploic space with altered marrow signal |
(a) Axial CT of the calvarium in a 17-year-old girl with TDT and a history of delayed onset transfusion therapy shows marked diploic space widening and “hair-on-end” appearance of the frontal and parietal bones. (b) CT topogram of the same patient as in (a) shows sparing of the occipital bone (arrow) as well as sparing of the ethmoid sinuses ( arrowhead). TDT, transfusion dependent thalassaemia. | Gosein, M., Maharaj, P., Balkaransingh, P., Banfield, R., Greene, C., Latchman, S., & Sinanan, A. (2019). Imaging features of thalassaemia. The British journal of radiology, 92(1095), 20180658. https://doi.org/10.1259/bjr.20180658
Hair‐on‐end appearance: lateral view. | Azam, M., & Bhatti, N. (2006). Hair-on-end appearance. Archives of disease in childhood, 91(9), 735. https://doi.org/10.1136/adc.2006.100032
Associated Clinical Features:
Patients with underlying hemoglobinopathies often also have: