Dermatology · Pigmentary Disorders
The facts most likely to be tested
Vitiligo is an autoimmune destruction of melanocytes resulting in well-demarcated, depigmented macules and patches.
The diagnosis is primarily clinical, but Wood's lamp examination will reveal bright blue-white fluorescence in affected areas.
Vitiligo is strongly associated with other autoimmune conditions, most notably autoimmune thyroid disease (Hashimoto's or Graves'), type 1 diabetes mellitus, and pernicious anemia.
The Koebner phenomenon describes the development of new vitiligo lesions at sites of physical trauma or skin injury.
First-line treatment for localized disease involves high-potency topical corticosteroids or topical calcineurin inhibitors.
Patients with extensive or refractory disease are candidates for narrowband ultraviolet B (NB-UVB) phototherapy to induce repigmentation.
Histopathology of a biopsy, if performed, would show a complete absence of melanocytes at the dermo-epidermal junction.
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A 28-year-old woman presents to the clinic with concerns about progressive skin changes. She notes the appearance of asymptomatic, milky-white patches on her hands and around her mouth that have gradually enlarged over the past year. She reports no history of prior skin trauma, but mentions she has been feeling increasingly fatigued and has a family history of Hashimoto thyroiditis. Physical examination reveals well-demarcated, depigmented macules on the dorsal aspects of both hands and perioral skin. A Wood's lamp examination demonstrates bright blue-white fluorescence in the affected areas.
What is the most likely diagnosis and the most appropriate next step in management?
Vitiligo; screen for associated autoimmune conditions including TSH and free T4.
The patient presents with classic depigmented patches characteristic of vitiligo, which is frequently comorbid with other autoimmune disorders, necessitating screening for thyroid dysfunction.
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High yield triage
Etiology / Epidemiology
Acquired autoimmune destruction of melanocytes; often associated with thyroid disease and pernicious anemia.
Clinical Manifestations
Well-demarcated, depigmented macules/patches; Koebner phenomenon is common.
Diagnosis
Wood's lamp examination reveals bright blue-white fluorescence.
Treatment
Topical corticosteroids (high potency) are first-line; skin atrophy is a major risk.
Prognosis
Chronic, progressive course; psychosocial impact is the primary morbidity.
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Epidemiology & Etiology
Vitiligo is an acquired condition resulting from the autoimmune destruction of melanocytes. It frequently presents in the second or third decade of life. Patients often have a personal or family history of other autoimmune disorders, most notably Hashimoto thyroiditis, Type 1 diabetes, and Addison disease.
Pertinent Anatomy
The condition involves the loss of functional melanocytes within the basal layer of the epidermis. The absence of melanin production leads to the characteristic loss of skin pigment. Hair follicles may also lose pigment, resulting in poliosis.
Pathophysiology
The primary mechanism is T-cell mediated destruction of melanocytes. Oxidative stress and genetic susceptibility (e.g., NLRP1 gene) trigger the immune response. The resulting loss of pigment is permanent unless repigmentation occurs via follicular melanocyte migration.
Clinical Manifestations
Presentation is characterized by milky-white, non-scaly macules with distinct borders. Lesions often appear in a symmetric distribution on the face, hands, and genitalia. The Koebner phenomenon—development of lesions at sites of trauma—is a classic board finding. Red flags include rapid, widespread progression, which may indicate underlying systemic autoimmune failure.
Diagnosis
Diagnosis is primarily clinical. A Wood's lamp examination is the gold standard for confirming depigmentation, showing bright blue-white fluorescence due to the absence of melanin. Biopsy is rarely required but would show a complete absence of melanocytes on Fontana-Masson stain.
Treatment
First-line therapy for localized disease is high-potency topical corticosteroids or topical calcineurin inhibitors. Skin atrophy and telangiectasia are significant risks with prolonged steroid use. For extensive disease, narrowband UVB (NB-UVB) phototherapy is the treatment of choice. Surgical grafting is reserved for stable, refractory cases.
Prognosis
The course is unpredictable and often progressive. Psychosocial distress and depression are common complications. Patients require screening for associated autoimmune endocrinopathies if clinical suspicion arises.
Differential Diagnosis
Pityriasis alba: fine scale and hypopigmentation rather than total depigmentation
Tinea versicolor: fine scale and positive KOH prep for spaghetti and meatballs hyphae
Post-inflammatory hypopigmentation: history of preceding rash or trauma
Chemical leukoderma: history of exposure to phenolic compounds
Nevus depigmentosus: stable, congenital, non-progressive hypopigmented patch