Differentials
Piebaldism
SIGNS / SYMPTOMS
Present at birth, non-progressive, coalescing depigmented patches, usually near the midline on the front, including a forelock of white hair.
INVESTIGATIONS
Clinical diagnosis.
Waardenburg's syndrome
SIGNS / SYMPTOMS
Achromic patches present at birth, white forelock, heterochromia iridium, dystopia canthorum, deafness and other neurological symptoms.
INVESTIGATIONS
Clinical diagnosis.
Tuberous sclerosis
SIGNS / SYMPTOMS
Typical ash-leaf-shaped hypopigmented macules, seizures, angiofibromas, and intellectual disability.
Occurs predominantly on the thorax and legs.
INVESTIGATIONS
Hypopigmentation and incomplete pigment loss when examined by Wood's lamp (UV light).
Lichen sclerosus
SIGNS / SYMPTOMS
Women: typically presents in females as pruritic white plaques in the genital area associated with epidermal atrophy and scarring. Vulvar involvement may present with dysuria and dyspareunia.
Men: occurs almost exclusively in those who are uncircumsised.
INVESTIGATIONS
Skin biopsy: reveals lichenoid infiltrate in the dermal-epidermal junction, hyperkeratosis, thinning, and loss of normal rete ridge in the epidermis.
Naevus depigmentosus
SIGNS / SYMPTOMS
Congenital condition usually noted at birth or in early childhood.
Hypopigmented solitary patch with jagged edges, typically on the trunk. Usually remains at the same site, but may grow in proportion to body growth.
INVESTIGATIONS
Hypopigmentation seen under Wood's lamp examination.
Naevus anaemicus
SIGNS / SYMPTOMS
Congenital vascular anomaly that is not considered a true pigmentary disorder.
Typically presents at birth or first noted in early childhood.
Presents as pale macules or patches. Lesions remain unchanged throughout the patient’s life.
INVESTIGATIONS
Lesions not accentuated under Wood's lamp examination.
Lesional pallor is due to vasoconstriction, not melanin loss; therefore, diascopy (pressing on the skin with a glass slide) makes it indistinguishable from the surrounding area.
No melanocyte abnormalities in histology.
Hypomelanosis of Ito
SIGNS / SYMPTOMS
Mosaic distribution of hypomelanotic macules and bands of speckled or mottled, greyish-brown to blue-black patches involving the skin, conjunctiva, sclera, tympanic membrane, and oral and nasal mucosa.
Hypochromic lesions in distinctive patterns (e.g., whirls, patches, streaks) on trunk, arms, legs, and face that follow the lines of Blaschko.
INVESTIGATIONS
Clinical diagnosis.
Incontinentia pigmenti
SIGNS / SYMPTOMS
Distribution along Blaschko's lines, history of vesicular eruption perinatally, female gender.
INVESTIGATIONS
Genetic testing for NF-kappa-B essential modulator (NEMO) mutation.
Pityriasis alba
SIGNS / SYMPTOMS
Asymptomatic ill-defined small patches with fine scaling typically on the cheeks of children and adolescents, often with atopic dermatitis.
INVESTIGATIONS
Clinical diagnosis.
Discoid lupus erythematosus
SIGNS / SYMPTOMS
Dyspigmentation (areas of hypo- and hyperpigmentation), infiltrated rim around leukoderma, follicular plugging, scarring alopecia.
INVESTIGATIONS
Lesional biopsy positive for direct immunofluorescence (e.g., basement membrane).
Hyperkeratosis with interface, perivascular, and periappendageal lymphocytic infiltrate in the dermis, as well as mucin infiltration.
Pityriasis versicolour
SIGNS / SYMPTOMS
Polycyclic, well-demarcated lesions with fine scaling, typically on the upper trunk.
INVESTIGATIONS
Pityrosporum orbiculare fluoresces yellow-green when exposed to Wood's lamp examination.
A scrape of skin scales reveals the organism on potassium hydroxide preparation.
Pinta
SIGNS / SYMPTOMS
Widespread pigmentary change with a mixture of hyperpigmentation and depigmentation that can be disfiguring.
INVESTIGATIONS
Positive serology, T pallidum carateum can be seen on darkfield microscopy of samples taken from the early papules.
Leprosy
SIGNS / SYMPTOMS
Hypopigmentation, hypoaesthesia, thickening of nerves, extended residence in or migration from endemic area.
INVESTIGATIONS
Tests for diagnosis include serology, pp65 antigenaemia test, histopathology and nucleic acid amplification, and detection systems, most commonly PCR.
Melanoma-associated leukoderma
SIGNS / SYMPTOMS
May be indistinguishable from vitiligo and thus is likely a form of vitiligo rather than a distinct entity; history of melanoma, leukoderma at an excision site, or melanoma or metastases found upon examination.
INVESTIGATIONS
Biopsy of suspicious melanocytic lesions characterised by loss of pigmentation in the primary lesion and an eccentrically placed hypopigmented macule.
Frostbite
SIGNS / SYMPTOMS
Well-defined leukoderma in areas of previous traumatic cold exposure.
INVESTIGATIONS
Clinical diagnosis.
Hypopigmented cutaneous T-cell lymphoma
SIGNS / SYMPTOMS
Less well-circumscribed than vitiligo, primarily hypopigmentation present on sun-protected areas of the body.
INVESTIGATIONS
Immunophenotype CD4 is positive, and CD7 negative; CD25 positivity is variable.
Hydroquinone-induced dermatopathy
SIGNS / SYMPTOMS
Ill-defined or patchy areas of hypopigmentation, history of using bleaching creams.
INVESTIGATIONS
Clinical diagnosis.
Corticosteroid-induced dermatopathy
SIGNS / SYMPTOMS
Ill-defined hypopigmentation, localised to area of topical or local corticosteroid therapy; associated dermal and epidermal atrophy, telangiectasia, purpura, acne.
INVESTIGATIONS
Clinical diagnosis.
Tyrosine kinase inhibitor-induced dermatopathy
SIGNS / SYMPTOMS
Therapeutic agents (e.g., imatinib, sunitinib) targeting c-kit may trigger or worsen vitiligo; may also induce hypopigmentation of skin or hair.
INVESTIGATIONS
Clinical diagnosis.
Vogt-Koyanagi-Harada syndrome
SIGNS / SYMPTOMS
Acquired depigmentation associated with ocular and auditory compromise.
INVESTIGATIONS
Clinical diagnosis.
Idiopathic guttate hypomelanosis
SIGNS / SYMPTOMS
Multiple small hypopigmented to depigmented macules preferring sun-exposed distal upper and lower extremities; accumulation of isolated lesions that do not coalesce.
INVESTIGATIONS
Clinical diagnosis.
Progressive macular hypomelanosis
SIGNS / SYMPTOMS
Progressive hypopigmented patches on the back, chest, and abdomen, typically in young black females.
INVESTIGATIONS
Skin biopsy with decreased pigment in the epidermis, but presence of melanocytes and a normal-looking dermis.
Wood's lamp examination may reveal an orange fluorescence due to the presence of Propionibacterium acnes.
Electron microscopy shows a shift from large melanosomes in normal-looking skin to small aggregated, membrane-bound melanosomes in hypopigmented skin.
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