Pigmentary disorders may cause locally or generally darker (hyperpigmentation) or lighter (hypopigmentation) skin.
Even though the skin lesions are usually asymptomatic, they may affect the patient's quality of life significantly (cosmetic disturbance and psychosocial problems).
Drugs and certain systemic diseases may cause generalized or local changes of skin colour.
Pathogenesis
Changes in skin colour are usually due to increased or decreased amounts of melanin pigment and/or of melanocytes (hyperpigmentation or hypopigmentation, respectively).
Chronic abrasion may lead to thickening of the epidermis, causing visible hyperpigmentation (e.g. calluses, mechanical abrasion, neurodermatitis).
In generalized pigmentary disorders the cause may be hormonal (e.g. melanocyte stimulation caused by high levels of melanocyte-stimulating hormone [MSH] in patients with hypocortisolism, or melasma during pregnancy).
Skin colour may also change due to metabolic products accumulating in the skin (such as bilirubin in patients with jaundice or iron in patients with haemochromatosis).
Diagnosis
The diagnosis is usually based on the patient history and clinical picture.
What colour are the skin lesions? Is the pigmentary disorder local or generalized? How have the skin lesions developed? Does their location change?
Does the patient have any history of diagnosed skin disorders, such as vitiligo or atopic eczema?
Has the patient developed skin reactions in association with sun exposure? Are the locations typical for photodermatitis (face, neck, chest, arms)?
Is it an acquired or a congenital disorder? Is there any family history of pigmentary disorders?
Hormonal changes, oral contraceptives or pregnancy
Oral medication or topical skin treatment, including natural drugs and treatments, sunscreen ointments and cosmetics
Examine the whole skin and mucosa, including the palms and soles of the feet.
Localized darkening of the skin (hyperpigmentation)
Asymptomatic, clearly defined white patches usually symmetrically on the limbs, on the trunk, in the navel area and on the nipples, on the face around the mouth and eyes
Postinflammatory hypopigmentation: when healing, many skin disorders, such as psoriasis and atopic eczema, may leave slowly fading, white patches.
Pityriasis alba
Slightly scaly, white patches predominantly on the face and upper limbs
Cause unknown; it may represent postinflammatory hypopigmentation and be associated with atopic eczema.
Has a chronic course
Less common causes
Depigmented naevi (halo naevi): a white, annular patch develops around a naevus.
Idiopathic guttate hypomelanosis
Small white patches on the limbs in photodamaged skin in the elderly
Clinical picture resembling confetti
Some topical drugs may cause white patches (retinoids, benzoyl peroxide and azelaic acid used for the treatment of acne, and topical and injectable glucocorticoids, for instance).
Progressive macular hypomelanosis
Asymptomatic white patches on the trunk, neck and proximal limbs, often merging in the midline
Usually in people with dark skin
Cause unclear
Piebaldism
Pigmentary disorder with autosomal dominant inheritance
White patches, most commonly on the scalp or facial area from birth
Hair or eyebrows grow white in the affected areas (poliosis).
May also occur on the trunk and limbs.
The location of the lesions does not change.
White patches in patients with tuberous sclerosis: white (ash-leaf) spots from birth on the trunk and limbs; additionally facial fibromas and epilepsy
Diffuse darkening of the skin and Addison's disease-like clinical symptoms and findings
Other symptoms include anaemia, neurological symptoms and atrophic glossitis
Acromegaly due to a pituitary tumour Pituitary Tumours and Cushing's syndrome Cushing's Syndrome: diffuse darkening of the skin due to melanocyte-stimulating hormone (MSH) secretion
Chronic exposure to sunlight, particularly on the face of elderly people
Deep furrows and yellowish skin tone
Workup
Further tests are rarely needed; the clinical picture is decisive.
In pityriasis versicolor and seborrhoeic eczema, Malassezia yeast may be seen on microscopy (native fungal examination) but fungal culture may still be negative. The diagnosis is based on clinical features.
Histological examination of a skin biopsy specimen may be helpful if a specific skin disorder is suspected. The biopsy specimen should be taken at an active stage of the disease.
Epicutaneous and/or photopatch tests may be indicated if allergic contact dermatitis is suspected.
If a pigmentary disorder due to an internal disease is suspected, targeted, stepped laboratory tests should be performed, as necessary.
Sun protection and use of a suitable sunscreen ointment often help.
Causal treatment (visceral diseases; avoidance of causative factor in allergic contact dermatitis, photodermatitis, drug-induced pigmentary disorders)
In the case of postinflammatory pigmentary disorders, treatment of the causative skin disease. The response for the actual pigmentary disorder is often poor but the skin tone often evens out within 6-12 months.
For local hyperpigmentation (melasma, postinflammatory hyperpigmentation) there is evidence of the efficacy of (2-4%) hydroquinone ointments Interventions for Melasma. Hydroquinone may require special permit.
In Finland, hydroquinone can no longer be prescribed for extemporaneous compounding. A hydroquinone-containing combination cream (Pigmanorm®) is available with special permit for compassionate use. A thin layer of the ointment is applied once daily, at night, in courses of 1-3 months until the skin area becomes lighter.
There is also some evidence for the efficacy of topical treatment with azelaic acid or retinoids (e.g. 0.025% or 0.05% tretinoin ointment).
For example, once daily, at night, in courses of 1-3 months, depending on response
In severe cases, topical treatment has been combined with glycolic acid peeling and laser treatments (possibly available through private health care only).
For hypopigmentation of other causes, there are no evidence-based treatments available.
Covering treatment and makeup
Specialist consultation
For severe pigmentary disorders or ones causing significant psychosocial suffering, consultation of a dermatologist should be considered.
References
Rivas S, Pandya AG. Treatment of melasma with topical agents, peels and lasers: an evidence-based review. Am J Clin Dermatol 2013;14(5):359-76. [PubMed]
Rajaratnam R, Halpern J, Salim A et al. Interventions for melasma. Cochrane Database Syst Rev 2010;(7):CD003583. [PubMed]
Jutley GS, Rajaratnam R, Halpern J et al. Systematic review of randomized controlled trials on interventions for melasma: an abridged Cochrane review. J Am Acad Dermatol 2014;70(2):369-73. [PubMed]
Kang HY, Valerio L, Bahadoran P et al. The role of topical retinoids in the treatment of pigmentary disorders: an evidence-based review. Am J Clin Dermatol 2009;10(4):251-60. [PubMed]
Whitton M, Pinart M, Batchelor JM et al. Evidence-based management of vitiligo: summary of a Cochrane systematic review. Br J Dermatol 2016;174(5):962-9. [PubMed]
Hu SW, Bigby M. Pityriasis versicolor: a systematic review of interventions. Arch Dermatol 2010;146(10):1132-40. [PubMed]
Ezzedine K, Whitton M, Pinart M. Interventions for Vitiligo. JAMA 2016;316(16):1708-1709. [PubMed]