What is Vitiligo?
Vitiligo is an acquired chronic autoimmune depigmentation disorder characterized by white patches resulting from progressive loss of functioning epidermal melanocytes, presenting as depigmented patches that are often symmetrical and increase in size over time. 1, 2
Disease Classification and Presentation
Vitiligo is classified into two main types based on distribution pattern 1:
- Non-segmental vitiligo (vitiligo vulgaris) is the most common form, characterized by symmetrical depigmented patches that typically increase in size over time, with average onset around age 20 years 1
- Segmental vitiligo presents as unilateral, asymmetrical depigmentation confined to one body segment, often following dermatome distribution or Blaschko's lines 1, 2
Common Sites of Involvement
- Vitiligo commonly affects fingers, wrists, axillae, groins, and body orifices including mouth, eyes, and genitalia 1
- The distribution in segmental vitiligo often follows neurologically defined regions, supporting a neural theory component to pathogenesis 2
Pathophysiology
The disease involves multiple mechanisms 3, 4:
- Autoimmune destruction is the primary driver, with CD8+ cytotoxic T cells and aberrantly activated skin-resident memory T cells destroying melanocytes 4
- Genetic predisposition with multi-genetic inheritance affecting melanocyte-specific genes (DDR1, XBP1, NLRP1, PTPN22) and overlapping with other autoimmune disorders 5
- Interferon-gamma (IFN-γ) signaling pathway creates inflammatory loops between keratinocytes, melanocytes, and immune cells that perpetuate disease progression 3
- Oxidative stress and environmental factors including chemical exposure and skin injury act as precipitating factors 3, 5
Critical Autoimmune Associations
Autoimmune thyroid disease occurs in approximately 34% of adults with vitiligo, making thyroid function screening essential in all vitiligo patients. 1
- The British Journal of Dermatology guidelines specifically recommend checking thyroid function and thyroid autoantibodies in all vitiligo patients 1
- Monitoring for development of other autoimmune conditions is important in long-term follow-up 1
Disease Activity Assessment
Disease activity classification is clinically more relevant than traditional staging 1:
- Stable disease is defined by no new lesions, no Koebner phenomenon, and no extension of existing lesions for at least 12 months 1
- Active disease shows progression with new lesions or extension of existing patches 1
- Wood's light examination helps delineate areas of pigment loss, particularly useful in lighter skin types 1, 2
Psychosocial Impact
- Vitiligo causes significant quality of life impairment regardless of classification, particularly in women and those with darker skin 1
- The visible nature of depigmentation results in profound psychosocial burden that should not be overlooked in management 1, 3
Common Diagnostic Pitfalls
- Failing to screen for thyroid disease can miss an important treatable comorbid condition that affects one-third of patients 1
- Atypical presentations require expert dermatology assessment to distinguish from other depigmenting conditions 1, 2
- Classical symmetrical presentations can be diagnosed confidently, but unilateral or unusual distributions warrant specialist evaluation 1