What is the diagnosis for a young female with whitish lesions in bilateral extremities, pinna, and occipital region, accompanied by mild itching and gradual increase in size?

Diagnosis: Vitiligo Vulgaris (Nonsegmental Vitiligo)

The most likely diagnosis is vitiligo vulgaris, an acquired chronic depigmentation disorder characterized by symmetrical white patches that gradually increase in size, affecting bilateral extremities, pinna, and occipital region in a young female with mild itching. 1

Clinical Features Supporting This Diagnosis

Distribution Pattern

• Vitiligo characteristically presents with symmetrical involvement of bilateral extremities, which matches this patient's presentation 1
• The pinna (ears) and occipital region are recognized sites for vitiligo involvement, particularly in areas exposed to friction or trauma (Koebner phenomenon) 1
• Common sites include fingers, wrists, axillae, groins, and body orifices, with the pattern described here being entirely consistent 1

Lesion Characteristics

• Vitiligo presents as porcelain-white or whitish patches with no surface change and usually no redness, distinguishing it from inflammatory conditions 1
• The lesions are often symmetrical and typically increase in size with time, matching the "gradually increasing" description 1
• A "trichrome" appearance (white center with intermediate pale area) may be present in some cases 1

Associated Symptoms

• While vitiligo typically has no surface change, mild itching can occasionally occur, particularly at the advancing edge of lesions 1
• Very occasionally, inflammation is seen at the advancing edge of a vitiligo macule, which could explain the mild pruritus 1

Key Differential Diagnoses to Exclude

Pityriasis Versicolor

• Presents with hypopigmented or hyperpigmented macules with fine scale, not the porcelain-white appearance of vitiligo 1, 2
• Wood's lamp shows yellowish-white or copper-orange fluorescence 2
• KOH preparation reveals "spaghetti and meatballs" appearance 2

Pityriasis Alba

• Typically affects children and presents with hypopigmented patches with fine scale, not complete depigmentation 1
• Usually limited to face and upper extremities, not the distribution described 1

Lichen Sclerosus

• Relevant for genital vitiligo differential but presents with porcelain-white papules and plaques with ecchymosis 1
• Primarily affects anogenital areas, not bilateral extremities and occipital region 1

Mycosis Fungoides-Associated Depigmentation

• Can present with whitish scaling lesions but typically shows patches, plaques, or tumors on histology 1, 3
• Acquired ichthyosis-like presentation would show fine scaling, not the smooth white patches of vitiligo 3

Diagnostic Approach

Clinical Examination

• Visual inspection of the skin lesions is the preferred means of diagnosis for vitiligo 1
• Assess for symmetrical distribution, porcelain-white color, absence of surface changes, and gradual size increase 1
• Examine for involvement of hair within patches (poliosis) and mucosal areas 1

Wood's Light Examination

• Wood's light delineates areas of pigment loss and can identify depigmentation not visible to the naked eye, especially in pale skin 1
• Actively depigmenting areas may appear more prominent under Wood's lamp examination 1

Laboratory Investigations

• Screen for autoimmune thyroid disease, as 34% of adults with vitiligo have thyroid dysfunction 1
• Check thyroid function tests and thyroid autoantibodies (anti-TPO, anti-thyroglobulin) 1
• Consider screening for other autoimmune conditions if clinically indicated 1

Critical Pitfalls to Avoid

• Do not perform skin biopsy routinely for typical vitiligo presentation, as diagnosis is clinical; biopsy is reserved for atypical cases 1
• Do not dismiss the psychological impact - vitiligo causes significant social anxiety, depression, and stigmatization requiring supportive counseling 1
• Do not overlook the association with autoimmune diseases - 32% have family history of autoimmune disease, and screening is essential 1
• Do not confuse with postinflammatory hypopigmentation, which has a history of preceding inflammation and is not progressive 1