Piebaldism
Piebaldism is a rare, autosomal dominant genetic disorder of melanocyte development. Unlike vitiligo, it is congenital and stable.
Key Clinical Features
- White Forelock: A characteristic patch of white hair on the frontal scalp is present in the vast majority of patients.
- Leukoderma: Symmetrical, stable patches of depigmentation, most commonly on the forehead, anterior trunk, and extremities.
- Islands of Pigmentation: The patches often contain islands of normally pigmented skin, which distinguishes them from other leukodermas.
Genetics & Pathophysiology
| Feature | Details |
|---|---|
| Mutation | Caused by mutations in the KIT proto-oncogene, which is essential for melanoblast survival and migration. |
| Difference from Vitiligo | Present at birth, stable (does not progress), and hair within the patches is often white. |
High-Yield Exam Pearl:
- Waardenburg Syndrome: Always rule out Waardenburg syndrome if there is associated sensorineural hearing loss, iris heterochromia, or dystopia canthorum.
- No Autoimmunity: Unlike vitiligo, piebaldism is not associated with autoimmune disorders like thyroid disease.