Disorders of Pigmentation
Pigmentation disorders result from changes in melanin production or distribution. They are categorized into hypopigmented (loss of pigment) and hyperpigmented (excess pigment) conditions.
Key Pigmentation Disorders
| Condition | Key Features |
|---|---|
| Vitiligo | Autoimmune destruction of melanocytes; depigmented (white) macules/patches. |
| Melasma | Hypermelanosis: symmetric brown patches on sun-exposed face, often hormonal/pregnancy-related. |
| Albinism | Genetic deficiency in tyrosinase; diffuse lack of melanin in skin, hair, and eyes. |
| Post-Inflammatory (PIH) | Hyperpigmentation occurring after resolution of inflammatory skin conditions (e.g., acne). |
Diagnostic Pearls
- Wood’s Lamp: Essential for distinguishing vitiligo (which glows bright white/blue-white) from other hypopigmented conditions (like tinea versicolor, which may appear yellow-gold).
- Vitiligo Associations: Frequently associated with other autoimmune conditions, most commonly thyroid disease.
High-Yield Exam Pearl:
- Café-au-lait Macules: Light brown patches. Always count them—6 or more measuring > 5mm (pre-puberty) or > 15mm (post-puberty) are diagnostic for Neurofibromatosis Type 1.
- Ash-Leaf Spots: Hypopigmented macules that are the earliest clinical sign of Tuberous Sclerosis.