A 25-year-old woman presents with well-defined chalk-white macules over the face, hands, and genitalia for 2 years. Wood's lamp examination shows brilliant white fluorescence with sharp borders. She has associated hypothyroidism. What is the pathomechanism?

• A Melanocyte proliferation with defective melanin synthesis
• B Defective melanosome transfer to keratinocytes
• C Autoimmune destruction of melanocytes ✓
• D Post-inflammatory melanin incontinence

Explanation

Vitiligo is caused by the autoimmune destruction of melanocytes, resulting in complete absence of melanocytes in the affected areas (confirmed by Masson-Fontana stain showing no melanin and anti-HMB-45 showing no melanocytes). The association with thyroid disease, type 1 diabetes, pernicious anemia, and Addison's disease supports an autoimmune polyglandular syndrome background. Wood's lamp examination enhances vitiligo macules to brilliant white, helpful in early or light-skinned patients.

Reference: Neena Khanna Illustrated Synopsis of Dermatology & STD, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.