Hypopigmented rashes

Clinical features

Pityriasis alba is a benign inflammatory skin condition that presents with poorly circumscribed hypopigmented oval or round macules, patches, or thin plaques.

• Pityriasis alba is generally asymptomatic; patients may seek medical attention because of the cosmetic appearance of the lesions.

• Occasionally, it is scaly and may cause mild pruritus.

• It affects children and adolescents more often than adults.

• It is more common, or at least more apparent, in patients with darker skin tones.

• Pityriasis alba is commonly located on the cheeks and proximal upper extremities.

• It frequently coexists with, and sometimes is considered to be a minor feature of, atopic dermatitis (AD).

• Pityriasis alba is seen more commonly during the summer or fall; sun exposure and tanning may accentuate the contrast between normal and hypopigmented skin.

Differential diagnosis

The important differential diagnoses include vitiligo, tinea versicolor, seborrheic dermatitis, nevus depigmentosus, nevus anemicus, postinflammatory hypopigmentation, mycosis fungoides, leprosy, and ash-leaf spots of tuberous sclerosis.

Work-up

• The diagnosis of pityriasis alba is usually established clinically.

• Skin biopsy is generally not needed.

• A Wood lamp examination can help distinguish pityriasis alba from vitiligo.

  • Pityriasis alba will appear accentuated with poorly defined borders, whereas vitiligo will show milky-white fluorescence with sharply demarcated borders.

• A potassium hydroxide (KOH) preparation can help distinguish pityriasis alba from tinea versicolor.

  • Pityriasis alba will not show fungal hyphae or spores, which are seen in tinea versicolor.

Initial steps in management

• Patients should be reassured of the benign nature of the condition.

• Treatment is usually not necessary.

• Sun protection can help minimize the demarcation between affected and nonaffected areas.

• Moisturizers can address scaling and potentially prevent the development of new lesions.

• Low-potency topical steroids, such as 1% or 2.5% hydrocortisone cream, or topical calcineurin inhibitors may be used if there is any erythema or pruritus.

  • Topical calcineurin inhibitors include tacrolimus ointment and pimecrolimus cream.

  • Tacrolimus is available in two strengths: 0.03% or 0.1% ointment.

  • Pimecrolimus is available as a 1% cream.

    • Topical calcineurin inhibitors have a U.S. Food and Drug Administration (FDA) black box warning associating their use with a theoretical risk for lymphoma because of the classification of systemic calcineurin inhibitors as immunosuppressive medications.

      • Patients can be reassured that most dermatologists believe these medications are safe to use and several professional organizations, including the American Academy of Dermatology, do not agree with this warning.

Warning signs/common pitfalls

Pityriasis alba is included in the differential diagnosis of hypopigmented or depigmented patches. Patients and sometimes physicians may be concerned that these lesions represent a more ominous depigmenting condition or an infectious process.

Counseling

The white spots on your skin are caused by a condition called “pityriasis alba.” This is not an infection, and it is not contagious. The cause of this condition is unknown; however, some believe it is a feature of atopic dermatitis or eczema. This condition will improve over a period of a few months to years and gradually the skin will return to normal pigmentation. Treatment is not necessary but if your skin is itchy, or if you desire treatment, we can try to use a low-potency topical steroid. Topical steroids should not be used for extended periods of time because their use may lead to side effects, such as thinning of the skin. An alternative treatment is a nonsteroidal antiinflammatory called a “topical calcineurin inhibitor,” such as tacrolimus ointment or pimecrolimus cream. Although these are labeled with an FDA black box warning regarding a theoretical increase in risk for lymphoma, most dermatologists believe they are safe to use, and studies have not shown any increased risk for cancer with topical use. Other interventions that may improve the appearance of skin are the use of sun protection and moisturizers.

Epidemiology

Vitiligo affects approximately 0.5% to 2% of the population worldwide. The peak incidence is in the 10- to 30-year-old age group with an average age of onset of approximately 20 years, although it can manifest any time from shortly after birth to late adulthood.

Clinical features

• Vitiligo classically presents as milky-white or chalky-white, nonscaling macules or patches that are completely depigmented with no overlying skin changes.

  • At initial onset, involved areas may appear lighter in color rather than completely depigmented.

  • There is a variant of active vitiligo, known as “trichrome vitiligo,” in which lesions can have an intermediate zone of hypochromia between normal and totally depigmented skin ( Fig. 8.1 ).

    

• The primary macules are often round or ovoid and become confluent as they enlarge, often leading to patches with irregular but sharply demarcated borders surrounded by normal skin.

  • Lesions range from millimeters to centimeters in diameter.

• Lesions in vitiligo are usually asymptomatic but can present with mild pruritis and/or loss of pigment in associated hair.

• Lesions can be stable or undergo centrifugal expansion at varying rates.

  • A stable lesion is defined as one in which no change is detected by serial photography in a 12-month period.

• Vitiligo can affect any area of the skin and mucous membranes.

  • It has a predilection for the extensor surfaces of the extremities (backs of the hands, elbows, and knees) and the periorificial areas (around the mouth, eyes, rectum, and genitalia).

• The distribution of lesions can be localized or generalized.

  • Localized lesions can be focal, segmental, or mucosal.

    • Focal means that one or more macules are in a single area but are not in a segmental distribution.

    • Segmental indicates that the macules do not cross the midline and instead involve only one segment of the body.

    • Mucosal means that there is only involvement of the mucous membranes.

  • Generalized lesions can have vulgaris, acrofacial, mixed, or universal distributions.

    • Vulgaris is a very common distribution with scattered and widely distributed patches and macules.

    • Acrofacial is another very common distribution with involvement of the face and distal extremities.

    • A mixed distribution is a combination of segmental type with acrofacial and/or vulgaris type.

    • Universal distribution is rare and shows near complete depigmentation.

• The Koebner phenomenon has been observed in vitiligo when areas have been subjected to repeated trauma, pressure, or friction.

Differential diagnosis

Early vitiligo is often misdiagnosed as pityriasis versicolor or medication-induced or chemical-induced leukoderma.

Work-up

• Vitiligo is a clinical diagnosis. A full skin examination should be performed in all patients presenting with vitiligo.

• A Wood lamp examination can be particularly useful in visualizing vitiligo in individuals with lightly pigmented skin because the lesions usually emit a bright blue-white fluorescence and appear sharply demarcated.

• Laboratory studies are usually not helpful in diagnosing vitiligo.

• Biopsy is usually not necessary, but if performed, will show an absence of melanocytes with or without associated inflammation.

• Vitiligo is associated with various conditions, although this association is not strong enough to warrant empiric screening for every patient. Careful history taking should be performed for all patients with new-onset vitiligo, and further tests should be ordered if the history and review of systems suggest the patient is at higher risk.

  • If personal or family history is suggestive of autoimmune disease, screening of autoimmune antibodies and titers should be ordered.

  • If history is concerning for associated thyroid disease, screening should be performed with serum thyroid-stimulating hormone.

  • If the patient presents with symptoms of diabetes mellitus, fasting blood glucose should be obtained.

Initial steps in management

There is no cure for vitiligo, but available treatment options can lead to satisfactory results. The goals of therapy are to stabilize depigmentation and induce repigmentation.

• Another important goal of therapy is to address the psychological needs of the patient.

Therapy for repigmentation is often prolonged and responses to treatment are variable. Therapy should be guided by the patient’s age and skin type, the extent and location of the vitiligo, and patient preference.

• Patients can have partial repigmentation, full repigmentation, or no response to treatment.

• A period of 8 to 12 weeks is needed to gauge whether a particular treatment is effective. For phototherapy, a much longer period (at least 6 months) is required.

For localized areas of vitiligo, topical medications are often used as first-line therapy.

• The choice of topical medication will depend on the site of the lesion and age of the patient.

  • In adults, lesions on the body may be treated with ultrapotent or potent corticosteroids.

  • Lesions on the face, neck, and intertriginous areas should be treated with calcineurin inhibitors to avoid skin atrophy.

  • Ultrapotent and potent corticosteroids are also avoided in children in favor of mid-potency corticosteroids or calcineurin inhibitors.

• Long-term steroids should be started and monitored by a dermatologist because of the risk for adverse effects, such as skin atrophy, telangiectasia, and hypertrichosis.

• When using steroids long term, regimens often include daily or twice daily application in a cyclical fashion, alternating with calcineurin inhibitors or drug holiday to minimize the risk for adverse effects.

For generalized vitiligo, narrowband ultraviolet B (NB-UVB) phototherapy is the first-line treatment.

• Patients should be counseled that this option requires frequent in-office treatments, generally 2 to 3 times per week.

• Side effects range from pruritus and erythema to sunburn like reactions and possible reactivation of latent herpes simplex virus.

Treatment with tofacitinib, an oral Janus kinase inhibitor, has also been shown to be effective in treating generalized vitiligo. This medication should only be prescribed by a specialist, however.

• Other oral immunosuppressants, including pulsed oral corticosteroids, methotrexate, and cyclosporine, can be considered in patients who cannot obtain coverage for tofacitinib.

Treatment with an excimer laser is an alternative therapy for more localized lesions.

A variety of surgical repigmentation techniques have also been successful, including minigrafting and autologous suction blister grafts.

• Surgical repigmentation is typically reserved for vitiligo patients with recalcitrant disease that has failed to respond to medical therapy and whose disease has remained stable for at least 6 months before surgical intervention.

  • It is a good treatment option for segmental vitiligo, which is otherwise recalcitrant to medical treatments.

For patients with disseminated and widespread vitiligo, depigmentation of the remaining normally pigmented skin is an alternative option.

• Depigmentation is most commonly performed using 20% monobenzyl ether of hydroquinone applied once or twice daily for a minimum of 9 to 12 months.

  • Patients should be counseled that this treatment option will require strict and lifelong photoprotection.

    • Patients who cannot adhere to strict photoprotection should not undergo this treatment.

Therapy for vitiligo should also address how the condition affects the quality of life of the patient. Vitiligo can have devastating psychosocial effects on the patient, including low self-esteem. Patients can also suffer from social stigmatization. The impact of vitiligo on quality of life should be thoroughly assessed, and psychological support and therapy should be offered to patients.

It is important to establish expectations for treatment in patients early in the discussion. Realistic expectations about the length and efficacy of treatment are helpful in achieving patient satisfaction.

• Because response to treatment is slow, patients can also be counseled to use cover-up makeup, such as Dermablend, on the face and other cosmetically significant areas.