Pigmentary Disorders
Pigmentary disorders result from either an overproduction, underproduction, or irregular distribution of melanin in the skin.
Key Classifications
| Disorder | Pathophysiology | Clinical Presentation |
|---|---|---|
| Vitiligo | Autoimmune destruction of melanocytes | Well-circumscribed, depigmented (white) macules/patches. |
| Melasma | Hormonal + UV-induced hypermelanosis | Symmetric hyperpigmented patches on the face (cheeks, forehead). |
| Café-au-lait | Increased melanin in epidermal keratinocytes | Light-brown, oval macules; >6 suggests Neurofibromatosis type 1. |
Diagnostic Pearls
- Wood’s Lamp Examination:
- Vitiligo: Appears as bright, chalky white patches (accentuated contrast).
- Epidermal Pigment (Melasma): Becomes more distinct/darker.
- Dermal Pigment: Does not change significantly in intensity.
- Post-Inflammatory Hyperpigmentation (PIH): Common sequela of acne or inflammatory dermatoses, especially in darker skin types (Fitzpatrick IV-VI).
High-Yield Exam Pearl:
- Vitiligo Associations: Frequently linked to other autoimmune conditions, most notably Thyroid disease (Hashimoto’s/Graves), Pernicious anemia, and Type 1 DM.
- Café-au-lait Spots: If you see more than 6, you must think of Neurofibromatosis type 1.