Diagnosis: Vitiligo
This is vitiligo, an acquired chronic depigmentation disorder characterized by progressive loss of functioning epidermal melanocytes, presenting as white patches that do not fluoresce under Wood's lamp examination. 1
Clinical Presentation Confirming Vitiligo
The clinical features in this case are classic for vitiligo:
- Progressive depigmentation patches over 5 years indicate the chronic, stepwise nature of melanocyte destruction 1
- Patches that do not tan with adjacent skin reflect complete loss of melanocytes, which are the melanin-producing cells responsible for tanning 2
- No fluorescence on Wood's lamp is characteristic of vitiligo, as Wood's light delineates areas of complete pigment loss without enhancement (unlike some fungal infections that fluoresce) 1
- No surface changes are expected in vitiligo skin, distinguishing it from inflammatory or scaly conditions 1
Pathogenic Mechanism
The pathogenesis involves autoimmune destruction of melanocytes, with multiple contributing factors:
Primary Autoimmune Mechanism
- Autoimmune-mediated melanocyte destruction is the predominant mechanism, where immune activation leads to progressive loss of functioning epidermal and hair follicle melanocytes 3, 2
- Approximately 34% of adults with vitiligo have autoimmune thyroid disease, reflecting the strong autoimmune connection 1, 4
- The condition shows genetic predisposition with polygenic, multifactorial inheritance overlapping with other autoimmune disorders 5, 2
Contributing Pathogenic Factors
- Increased oxidative stress contributes to melanocyte destruction 2
- Genetic factors involving melanocyte-specific genes (DDR1, XBP1, NLRP1, PTPN22) play a role 2
- Neural theory may explain distribution patterns, particularly in segmental variants where lesions follow dermatomes or Blaschko's lines 3
Essential Clinical Actions
Screen for thyroid function immediately, as the British Journal of Dermatology guidelines specifically recommend checking thyroid function in all adults with vitiligo given the 34% prevalence of autoimmune thyroid disease 1, 4
Diagnostic Confirmation
- The diagnosis is straightforward in classical presentations and can be made confidently in primary care 1
- Wood's light examination confirms complete depigmentation (no fluorescence) and helps assess disease extent 1
Common Pitfall
Failing to screen for thyroid disease is a critical error, as this represents a treatable comorbidity present in one-third of vitiligo patients 4, 3