Discolorations of the skin include disorders of hypopigmentation (lightening), disorders of hyperpigmentation (darkening), and disorders caused by abnormal deposition of any pigment that alters skin color. The abnormal pigmentation can be endogenous (e.g., iron in hemochromatosis) or exogenous (e.g., a medication, such as minocycline) in origin.
Depigmentation
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Albinism
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Piebaldism
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Vitiligo
Hypopigmentation
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Nevus depigmentosus
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Pityriasis alba
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Postinflammatory hypopigmentation
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Tinea versicolor
Hyperpigmentation
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Acanthosis nigricans
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Addison disease
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Confluent and reticulated papillomatosis
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Melasma (chloasma)
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Postinflammatory hyperpigmentation
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Tinea versicolor
Yellow Discoloration
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Carotenoderma
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Jaundice
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Quinacrine
Blue-Gray Discoloration
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Amiodarone
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Argyria (silver)
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Chloroquine
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Chlorpromazine
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Hydroxychloroquine
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Minocycline
Important History Questions
How long has the abnormal color been present?
Some discolorations are congenital (e.g., albinism, nevus depigmentosus), but most are acquired (e.g., vitiligo).
How are you treating this discoloration?
Many patients use over-the-counter (OTC) or prescription remedies that may alter the clinical appearance.
Is the color change stable, progressive, or resolving?
Some disorders, such as pityriasis alba on the face of a young child, are waxing and waning. Other conditions, such as albinism, are largely stable. Still yet, other conditions are progressive. For example, dyspigmentation from minocycline worsens until discontinuation.
Do you have photos of the affected area, taken at an earlier time, when the pigmentation was not present?
Although not always the case, sometimes discoloration may be better appreciated with a prior frame of reference.
What medications are you taking?
Numerous drugs can alter skin color, with some common drugs listed in the box.
Important Physical Findings
What is the color of the abnormal skin?
This is a critical physical finding because it will determine what questions regarding the history will be necessary.
What is the distribution of the color change?
Some discoloration is unilateral (e.g., segmental vitiligo) or localized to certain areas (e.g., pityriasis alba affects the face), whereas other conditions are generalized (e.g., jaundice, albinism).
Is the change in pigmentation sharply demarcated?
Some forms of dyspigmentation or depigmentation (e.g., vitiligo) have sharp demarcation, whereas other forms (e.g., postinflammatory hypopigmentation) are more poorly demarcated.
If it is not clear whether something is hypopigmented or depigmented, use your Wood light.
Use of a Wood lamp is discussed in more detail in Chapter 2 . In general, disorders with true depigmentation (e.g., vitiligo, piebaldism) accentuate greatly with use of a Wood lamp, whereas disorders of lesser hypopigmentation (e.g., postinflammatory hypopigmentation) accentuate to a lesser degree.
Vitiligo
ICD10 code L80
AUTOIMMUNE DISORDER
Pathogenesis
Vitiligo is an autoimmune disease characterized by the destruction of melanocytes that produce melanin pigmentation for the skin. It is widely thought that vitiligo is an autoimmune disease, but other mechanisms of melanocyte death have been postulated by some authors. There is likely also a hereditary component because 8% of adults with vitiligo have similarly affected family members. Vitiligo is relatively common, with about 1% to 2% of the population affected. The condition is more noticeable in those with darker skin. The condition is associated with autoimmune disorders of other tissues and organ systems, such as Graves disease, Addison disease, Hashimoto thyroiditis, and alopecia areata.
Clinical Features
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Vitiligo can present at any age, but most cases of vitiligo occur before 20 years of age.
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Early lesions of vitiligo may demonstrate a faint rim of erythema or an eczematous border ( Fig. 27.1 ).
Fig. 27.1
Patient with early vitiligo demonstrating erythema and scale at the advancing edge. This degree of inflammation is unusual.
(From the Joanna Burch Collection, Aurora, CO.)
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The primary lesion is a depigmented macule, with a sharply demarcated border that may be scalloped.
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Lesions may be symmetric ( Fig. 27.2 ), focal, linear ( Fig. 27.3 ), or generalized (e.g., vitiligo universalis).
Fig. 27.2
Patient with severe vitiligo demonstrating the tendency for a symmetric distribution.
(From the Walter Reed Army Medical Center Collection, Washington, DC.)
Fig. 27.3
Segmental vitiligo in a young child affecting the lateral thorax and arm.
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Vitiligo can involve mucosal surfaces, such as the lips or genitalia ( Fig. 27.4 ).
Fig. 27.4
Patient with vitiligo of the mucosal surfaces of the lip demonstrating a sharp demarcation between depigmented areas and normal skin.
Diagnosis
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The clinical presentation of macular depigmentation in characteristic anatomic locations is usually diagnostic.
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Wood lamp examination is useful because it accentuates true depigmentation and thereby distinguishes vitiligo from other conditions of hypopigmentation, with lesser accentuation.
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Early lesions may require a biopsy. It is useful to take 3-mm or larger punch biopsies from lesional and normal skin so that the dermatopathologist can compare the pigment (this often requires a special stain for melanin) and judge melanocyte density (this requires an immunohistochemical stain for melanocytes) between affected and unaffected sites.
Treatment
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Vitiligo is a chronic disease that is not typically managed in an acute care environment. Any response to therapy is slow and incomplete.
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Initial care recommendations in an acute setting may include sunscreen use to protect the area from sunburn and to diminish differences between the adjacent tanned skin and depigmented skin, a medium-potency topical corticosteroid (0.1% triamcinolone) for affected areas of the trunk and extremities, or 0.1% hydrocortisone valerate for facial lesions.
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The patient should be referred to a dermatologist who may continue topical therapy (perhaps with alterations in corticosteroid strength), or who may employ ultraviolet (UV) light therapy. Psoralen plus UVA or narrow-band UVB therapy may be initiated. In one randomized, double-blind study, it was found that narrow-band UVB therapy is superior to PUVA therapy, but there are certain cases that do not respond well to any modality.
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Topical tacrolimus (0.03%–0.1% ointment bid) is an alternative to topical corticosteroid therapy.
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Topical pimecrolimus (1% cream bid) for at least 3 months is also an alternative to topical corticosteroids.
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Rare cases are treated surgically (e.g., melanocyte transplantation), but this is the domain of the specialist.
Clinical Course
Vitiligo cannot be cured. Many patients continue to develop new lesions of vitiligo over their lifetime. In general, about 70% of patients with vitiligo improve with therapy. A systematic review of the literature, combined with the results of patient questionnaires, suggested that topical corticosteroids are the best therapy for localized disease, and that narrow-band UVB is the best therapy for generalized disease.
Pityriasis Alba
ICD10 code L30.5
INTERNAL DISORDER
Pathogenesis
Pityriasis alba is a low-grade form of eczema that presents, by definition, as hypopigmentation. Although the pathogenesis is not fully understood, studies suggest it is a variant of atopic dermatitis. Photoexposure accentuates the condition because light preferentially tans normal adjacent skin.
Clinical Features
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Pityriasis alba usually affects children between the ages of 6 and 12 years of age. In most series, 90% of patients are within this age range. Less often, the condition affects younger children or older adolescents.
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Pityriasis alba is more noticeable in children with darker skin.
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The condition is asymptomatic in most cases. Occasionally, patients report mild pruritus.
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The face, especially the cheeks, is most often affected. Less often, it affects the upper extremities.
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Early lesions consist of round to oval areas of subtle erythema, with variable fine white scale.
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Mature lesions demonstrate ill-defined patchy hypopigmentation with round to oval areas, with a subtle fine white scale ( Figs. 27.5–27.7 ).
Fig. 27.5
Pityriasis alba demonstrating hypopigmented macules on the face.
(From the Joanna Burch Collection, Aurora, CO.)
Fig. 27.6
Pityriasis alba on fair skin is usually more subtle. This patient also has background erythema from his atopic dermatitis.
Fig. 27.7
Patient with pityriasis alba of the arms. This is often confused with hypopigmented tinea versicolor.
Diagnosis
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The clinical presentation is diagnostic in most cases. A history of atopic dermatitis or an atopic diathesis (see Fig. 27.6 ) in the patient or in family members supports the diagnosis.
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The differential diagnosis includes tinea versicolor, early vitiligo, postinflammatory hypopigmentation, and nevus depigmentosus. Hypopigmented mycosis fungoides is also in the differential diagnosis, but this is an extremely rare condition (less than one case per 4 million persons per year). Moreover, it is unusual for hypopigmented mycosis fungoides to occur exclusively on the face.
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Tinea versicolor may be excluded by performing a potassium hydroxide (KOH) examination.
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Vitiligo can usually be excluded on clinical grounds because it results in depigmented skin, whereas pityriasis alba results in hypopigmented skin. This difference can be accentuated with a Wood lamp examination (see Chapter 2 ). Also, the primary lesions of vitiligo are usually sharply demarcated, whereas pityriasis alba manifests a gradual transition to normal skin at the edges of lesions.
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Nevus depigmentosus can usually be excluded because it is solitary, sharply demarcated, and lacks any scale.
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Rare cases may require a 3-mm punch biopsy. Histologic examination usually demonstrates a low-grade spongiotic dermatitis with variable scale that is consistent with pityriasis alba.
Treatment
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The condition is benign and self-limited, and reassurance alone is a reasonable option.
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Broad-spectrum sunscreens lessen visible differences between the hypopigmented macules and adjacent tanned skin.
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Lubrication with urea-containing and lactate-containing moisturizers is an often employed treatment, but it typically takes weeks to months of use to observe a response.
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All patients should be switched to a mild facial soap, such as Dove, Cetaphil, or Aveeno.
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A low-potency topical corticosteroid, such as 1% hydrocortisone cream or 0.05% desonide cream may be beneficial in some cases.
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Topical tretinoin and topical pimecrolimus have been reported to be efficacious but are more costly.
Clinical Course
Individual lesions typically last from months to years—up to 7 years has been documented—but the condition is benign and without any consequences.
Lichen Sclerosus et Atrophicus
ICD10 code L90.0 (nongenital)
AUTOIMMUNE DISORDER
Pathogenesis
Lichen sclerosus et atrophicus (LSA) or, simply, lichen sclerosus, is a disorder characterized by an atrophic epidermis, altered collagen in the superficial dermis, and an overlying white or white-blue appearance to the skin. The terms balanitis xerotica obliterans and kraurosis vulvae have been applied to genital lesions of LSA in men and women, respectively. The pathogenesis of LSA is poorly understood, but the increased incidence of LSA with other autoimmune diseases (e.g., morphea) and the presence of autoantibodies directed against extracellular matrix protein 1 suggest LSA is an autoimmune disorder.
Clinical Features
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LSA may present at any age, from pediatric to geriatric age groups.
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The condition is more common in women.
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The anogenital region alone is affected in about 50% of cases, anogenital and extragenital disease is present in about 25% of cases, and only extragenital areas are affected in about 25% of cases.
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Extragenital LSA is common on the neck, wrists, and inframammary areas.
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Anogenital LSA in girls and women often demonstrates an hourglass-like or figure-eight configuration that surrounds the genitalia and anal region.
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Early LSA may be pruritic or asymptomatic.
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Primary lesions quickly evolve into white atrophic areas ( Fig. 27.8 ), with variable telangiectasias.
Fig. 27.8
Patient with classic truncal lichen sclerosus et atrophicus demonstrating an atrophic wrinkled epidermis, with a white color.
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Some cases demonstrate surrounding brown hyperpigmentation.
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Variable features include hyperkeratosis and follicular plugging, fissures, blister formation ( Fig. 27.9 ), hemorrhage ( Fig. 27.10 ), and ulceration.
