Hair Color Change from Black to Brown on Left Hand
The most likely cause is vitiligo affecting the hair follicles, which can cause depigmentation of hair in localized areas, turning dark hair white or lighter in color. 1
Primary Diagnosis: Vitiligo with Hair Involvement
Vitiligo commonly affects melanocytes in hair roots, resulting in white or depigmented hair within affected skin patches. 1 The unilateral presentation on the left hand suggests this could be segmental vitiligo, which is confined to one unilateral segment and represents a distinct variant of the condition. 1
Key Clinical Features to Assess:
Examine the skin underlying the affected hair - Look for white patches or depigmented areas on the skin of the left hand, as vitiligo typically causes visible skin depigmentation before or concurrent with hair color changes. 1
Check for symmetry - Segmental vitiligo affects one side only (as in this case with the left hand), while nonsegmental vitiligo is typically symmetrical and would affect both hands. 1
Inspect common vitiligo sites - The fingers and wrists are among the most common sites affected by symmetrical vitiligo, making the hand a typical location. 1
Look for associated autoimmune conditions - Screen for thyroid disease, as 34% of adults with vitiligo have autoimmune thyroid disease, and obtain a family history of autoimmune conditions (present in 32% of patients). 1
Diagnostic Approach
Use Wood's light examination to delineate areas of pigment loss that may not be visible to the naked eye, especially in pale skin. 1 This UV examination can reveal depigmented areas that are larger than what appears under visible light. 1
Dermoscopy should be performed to look for characteristic features including yellow dots, exclamation mark hairs, and cadaverized hairs if alopecia areata is being considered in the differential. 2
Laboratory testing is generally unnecessary for typical vitiligo presentations, as the diagnosis is made clinically. 1 However, consider thyroid function testing (TSH) given the strong association with autoimmune thyroid disease. 1
Important Differential Considerations
Rule Out Other Causes:
Post-traumatic depigmentation - Inquire about any trauma, burns, or injury to the left hand that could cause localized pigment loss. 1
Chemical exposure - Ask about occupational or topical exposures that could cause drug-induced or topical depigmentation. 1
Alopecia areata - While this typically causes hair loss rather than color change, it can affect hair pigmentation and is associated with vitiligo. 2
Premature graying - However, this would typically be bilateral and more diffuse, not localized to one hand. 3
Common Pitfalls to Avoid
Do not assume this is normal aging or graying - Unilateral hair color change in a 25-year-old is pathological and warrants investigation. 1
Do not overlook the psychological impact - Vitiligo can cause considerable psychological and social disability, particularly in visible areas like the hands. 2
Do not order excessive laboratory tests when the clinical diagnosis is evident from examination showing depigmented skin patches. 2
Clinical Significance
If vitiligo is confirmed, counsel the patient that this is an autoimmune condition with unpredictable progression. 1 Segmental vitiligo (unilateral) typically has a more stable course than nonsegmental vitiligo and may not progress beyond the initial segment. 1
Serial photographs should be used to monitor any progression of depigmentation. 1