Review Question - QID 107863

This 8-year-old boy presenting with leukotrichia and slowly evolving, painless depigmented patches over areas of friction and trauma (hands, genitals, knees) has vitiligo. The diagnosis of vitiligo can be confirmed through visualization of lesions under a Wood's lamp, as hypopigmentation will fluoresces bright blue-white) due to accumulated biopterins (Illustration A).

Vitiligo is a chronic, progressive skin condition characterized gradual depigmentation over discrete areas of skin. Vitiligo results from immune-mediated destruction of melanocytes, though the exact etiology of vitiligo is unknown. It has been associated with other autoimmune conditions, such as pernicious anemia, Hashimoto's hypothyroidism, and type 1 diabetes mellitus. Patients typically present with discrete areas of pigment loss, typically over areas of the skin with increased friction (hands, feet, inner thighs, genitalia, perioral). Patients are at increased risk of sun damage in affected areas.

Plensdorf et al. review the common disorders of pigmentation. Common causes of acquired hypopigmentation include post-inflammatory hypopigmentation, vitiligo, pityriasis alba, and tinea versicolor. Vitiligo is found in ~1% of the population with equal preponderance in the sexes. 30% of patients have a family history of vitiligo. Treatment includes sun protection, cosmetic coverage, phototherapy, topical steroids, and/or calcineurin inhibitors. Areas of the face are typically more responsive to repigmentation therapies than the extremities.

Stinco et al. conducted a randomized control trial to compare narrow band UVB, topical pimecrolimus and topical tacrolimus in the treatment of vitiligo. 44 patients were followed over 24 weeks of therapy. No statistically significant differences in repigmentation for any anatomical site were recorded across the three treatment groups. The best results were obtained for lesions of the face with pimecrolimus cream and tacrolimus ointment and of the neck with NB-UVB.

Figure A shows pigment loss typical of non-segmental vitiligo over the interphalangeal joints. Figure B demonstrates loss of hair pigment over the occiput, a common occurrence in vitiligo (called leukotrichia). Illustration A shows the fluorescence of depigmented vitiligo patches under Wood's lamp.

Incorrect Answers
Answer 1: Anti-Rho antibodies are sensitive markers for diagnosing Sjogren's disease.
Answer 2: Punch biopsies are used for further diagnostic clarity for dermatological lesions; however, a punch biopsy is not needed to diagnose vitiligo.
Answer 4: A Darier's scratch test is used to diagnosis cutaneous mastocytosis.
Answer 5: Tzanck smears are used to diagnosis herpetic infections (herpes simplex virus or varicella zoster virus).