What are the differential diagnoses for plaque-like lesions on the dorsum of both hands associated with hypopigmentation?

Differential Diagnoses for Hypopigmented Plaques on Dorsum of Both Hands

The most critical differential diagnoses to consider are vitiligo, lichen sclerosus (extragenital), idiopathic guttate hypomelanosis, pityriasis versicolor, postinflammatory hypopigmentation, and morphea/scleroderma. 1

Primary Differential Diagnoses

Vitiligo

• Bilateral symmetrical distribution on hands is classic for vitiligo, particularly affecting fingers and wrists 1
• Look for complete depigmentation (chalk-white) rather than hypopigmentation
• No surface texture changes—skin appears normal except for color
• May show trichrome pattern (white center with intermediate pale zone)
• Screen for thyroid autoantibodies (34% have autoimmune thyroid disease) 1
• Use Wood's lamp to delineate extent in pale skin 1

Lichen Sclerosus (Extragenital)

• Presents as white plaques with atrophic or occasionally hypertrophic surface 2
• Extragenital LS can affect hands, though less common than genital sites
• Surface shows characteristic porcelain-white appearance with possible hyperkeratosis
• Histology shows lymphocytic infiltrate and scarring 2

Idiopathic Guttate Hypomelanosis

• Multiple small (2-5mm) hypopigmented macules on sun-exposed areas 1
• Typically affects dorsal hands and forearms in older individuals
• Lesions are discrete, not confluent plaques
• Associated with chronic sun exposure 3

Pityriasis Versicolor

• Perform KOH wet mount immediately—this is diagnostic 4
• Shows "spaghetti and meatballs" pattern on microscopy
• Lesions have fine scale that may not be obvious
• Can present as hypopigmented patches on hands, though trunk more typical 1

Postinflammatory Hypopigmentation

• History of preceding inflammation, trauma, or dermatosis is key 1, 3
• May follow psoriasis, eczema, scleroderma, or trauma
• Distribution corresponds to previous inflammatory process
• Gradual improvement expected over months

Less Common but Important Considerations

Morphea/Localized Scleroderma

• Indurated plaques with hypopigmentation and possible violaceous border
• Skin feels bound down, lacks normal texture
• May show "lilac ring" at active border
• Requires biopsy showing dermal sclerosis

Confetti-Like Leukoderma

• Multiple 1-3mm hypopigmented macules in confetti pattern 5
• Exclude systemic sclerosis, arsenicosis, and drug reactions
• Idiopathic form is rare but documented 5
• Requires extensive workup to exclude secondary causes

Disseminated Hypopigmented Keratoses

• Keratotic texture is the distinguishing feature 4
• Benign, slowly progressive
• Dermatoscopy and KOH help differentiate from other conditions 4

Diagnostic Approach Algorithm

1. Examine surface texture:

   • Smooth → Consider vitiligo, idiopathic guttate hypomelanosis
   • Keratotic/rough → Consider disseminated hypopigmented keratoses, lichen sclerosus
   • Indurated → Consider morphea

2. Assess pigment loss degree:

   • Complete depigmentation (chalk-white) → Vitiligo most likely
   • Partial hypopigmentation → Broader differential

3. Perform bedside tests:

   • KOH preparation to exclude pityriasis versicolor 4
   • Wood's lamp examination to assess extent 1
   • Dermatoscopy for pattern recognition 4

4. Obtain history:

   • Preceding inflammation/trauma → Postinflammatory hypopigmentation
   • Chemical/drug exposure → Drug-induced depigmentation 1
   • Family history → Consider genetic conditions (piebaldism, tuberous sclerosis)
   • Autoimmune disease history → Vitiligo more likely 1

5. Consider biopsy if:

   • Diagnosis remains unclear after clinical assessment
   • Atypical features present
   • Treatment planning requires confirmation
   • Need to exclude melanoma-associated leukoderma 1

Critical Pitfalls to Avoid

• Do not assume vitiligo without examining for surface changes—lichen sclerosus and morphea require different management 2
• Always perform KOH examination—missing pityriasis versicolor leads to inappropriate treatment 4
• Screen for thyroid disease in suspected vitiligo cases (34% association) 1
• Consider drug-induced causes, particularly in patients on new medications 1
• Bilateral hand involvement with plaques in older diabetic patients may represent actinic changes or keratoelastoidosis 6, 7

The bilateral symmetrical distribution on dorsal hands strongly suggests vitiligo as the primary consideration, but the description of "plaque-like" lesions warrants careful surface examination to exclude lichen sclerosus, morphea, or keratotic disorders that require distinctly different therapeutic approaches.