Segmental Vitiligo
A subtype of vitiligo characterized by depigmentation that follows a dermatomal or quasi-dermatomal distribution. It is distinct from generalized vitiligo in its clinical course and underlying mechanism.
Key Clinical Features
- Distribution: Unilateral and sharply demarcated, usually stopping abruptly at the midline.
- Onset: Typically occurs in childhood; rapid progression for 1–2 years followed by stabilization.
- Stability: It is remarkably stable and rarely crosses the midline or becomes generalized.
Diagnostic & Management Differences
| Aspect | Details |
|---|---|
| Autoimmune Link | Unlike generalized vitiligo, it has no significant association with other autoimmune conditions. |
| Treatment | Often resistant to standard medical management; surgical grafting (e.g., melanocyte-keratinocyte transplantation) is frequently successful due to the localized, stable nature of the disease. |
High-Yield Exam Pearl:
- Pathogenesis: Thought to be caused by a mosaic somatic mutation (the “neurogenic hypothesis” or “melanoblast migration hypothesis”), rather than the autoimmune destruction seen in non-segmental (generalized) vitiligo.
- Associated Features: Poliosis (white hair) within the patch is very common and serves as a classic physical exam finding.