Inflammatory Dermatoses

Dermatitis is inflammation of the skin. Inflammatory dermatoses are a group of chronic and acute disorders characterized by redness or inflammation of the skin. The following types of inflammatory dermatoses are covered in this section:

• Contact Dermatitis

• Keratosis Pilaris

• Pityriasis Alba

• Psoriasis

Contact Dermatitis

Contact dermatitis is an inflammatory dermatosis caused by an external source. The two types of contact dermatitis are allergic and irritant. These disorders should be suspected in the presence of well-defined, pink or red, scaly or bullous plaques in a linear or geometric configuration.

Allergic Contact Dermatitis

Allergic contact dermatitis is an acquired type IV hypersensitivity reaction due to exposure to an antigen in a sensitized person. Sensitization can occur over variable periods of time; symptoms generally develop within 12 hours of re-exposure.

Presentation: Pruritus is the predominant symptom. Rarely, systemic allergic contact dermatitis, caused by introduction of an allergen through a route other than the skin, can result in a rash (e.g., ingestion of nickel-rich foods can cause a rash in patients with a nickel allergy). Allergic contact dermatitis can present as diaper dermatitis in the case of allergy to methylchloroisothiazolinone (MCI) or methylisothiazolinone (MI). Both compounds are used as preservatives in personal care products, including baby wipes.

Causes: Common causes of allergic contact dermatitis in children include the following:

• cobalt

• formaldehyde

• fragrance

• gold

• lanolin/wool alcohols

• Myroxylon pereirae (balsam of Peru)

• nickel

• neomycin

• potassium dichromate

• Toxicodendron spp. (poison ivy, poison oak)

Diagnosis: The following are clues to the diagnosis of allergic contact dermatitis (see images here):

• pruritus

• distribution of findings that are linear or geometric, or in a characteristic location

• history of relevant exposure

The gold standard procedure for the diagnosis of allergic contact dermatitis is skin patch testing. Skin patch testing is a systematic process whereby a patient’s skin is exposed to antigens of interest, and after several days the skin is visually inspected for signs of allergic reaction.

Irritant Contact Dermatitis

Irritant contact dermatitis is caused by direct damage to the skin by an irritating substance. Offending substances include caustic agents such as saliva and feces or external irritants including soap or other cleaning agents. Irritant dermatitis does not require prior sensitization.

Diaper dermatitis is the most common form of irritant contact dermatitis in children. It can be identified by prominent involvement of the convex surfaces of the skin in the diaper area with sparing of the folds.

Another example of irritant contact dermatitis is “lip-lickers dermatitis,” which presents as dry, inflamed skin around the lips. Irritant contact dermatitis of the face is especially common among young infants due to drooling.

Treatment: The gold standard for treatment of diaper dermatitis in infants is frequent and thick application of barrier products (e.g., zinc oxide paste or petroleum jelly ointment). Irritant dermatitis of the face is treated by avoidance of irritating products or behaviors as well as frequent and thick application of barrier products, low-potency topical steroids, and occasionally, treatment with antifungal or antibacterial agents for secondary bacterial or fungal infections.

Keratosis Pilaris

Keratosis pilaris is a common disorder of the hair follicle that presents as small, follicular-based papules with perifollicular erythema. The lesions are symmetrically distributed and favor the extensor surfaces of the arms, thighs, and lateral cheeks. Keratosis pilaris of the lateral cheeks is more common in younger children than in adolescents. The etiology is unknown but often affects patients with xerotic conditions (e.g., atopic dermatitis or ichthyosis vulgaris).

Multiple skin-colored papules on the extensor surface of the arms with associated skin erythema. (Photograph courtesy of Elizabeth Dupuy.)

Treatment: Although keratosis pilaris is typically asymptomatic, it can be cosmetically distressing. Treatment is aimed at managing the keratosis and erythema, but therapy must be maintained to achieve continued improvement and remission. Bland emollients can be used in infants and young children. Keratolytic agents (e.g., urea, lactic acid, mild retinoids, and salicylic acid) can be helpful in older children and adolescents. Low-potency topical glucocorticoids or topical calcineurin inhibitors can be used to alleviate pruritus or erythema. The natural history of keratosis pilaris is variable, but many clinicians consider it a chronic condition.

Pityriasis Alba

Pityriasis alba is a nonspecific inflammatory dermatitis characterized by asymptomatic, hypopigmented, poorly circumscribed, flat or slightly scaly patches that often present on the cheeks and proximal upper extremities. This inflammatory dermatitis is more common in patients with atopic dermatitis and more apparent in individuals with darker skin. Sun exposure enhances the contrast between normal and affected skin, leading to perceived worsening during the summer months.

Pitryiasis alba presents with poorly circumscribed hypopigmented patches, commonly on the face. (Photograph courtesy of Carol Cheng, MD.)

Treatment: Moisturizers are used to minimize scale and dryness and can prevent recurrence. Sun protection should be emphasized. Mild topical glucocorticoids or calcineurin inhibitors can be used to decrease inflammation. Patients and their families should be counseled that postinflammatory hypopigmentation can take months to improve.

Psoriasis

Psoriasis is a common immune-mediated inflammatory dermatitis in children that is thought to be triggered by environmental factors in genetically susceptible patients. Psoriasis is caused by T-cell hyperactivity due to problems in the innate and adaptive immune system.

The lifetime prevalence of psoriasis is 2%-3% worldwide. One-third of psoriasis begins in childhood. The peak age of onset for pediatric psoriasis is between ages 7 and 10 years. Similar to many chronic conditions, psoriasis is characterized by a relapsing and remitting clinical course.

The most common genetic risk factor for early-onset psoriasis is HLACw6. Many other genes have been associated, and most are related to immune function.

Risk Factors

The following are risk factors for development of psoriasis:

• streptococcal infections of the pharynx and perianal skin

• environmental or psychosocial stress

• antimalarial medications

• glucocorticoid withdrawal

Clinical Presentation

Several phenotypes of psoriasis with variable severity exist. The prototypical lesion is a well-circumscribed, bright-pink plaque with characteristic gray-silver scale. Studies indicate that children are more likely than adults to develop guttate psoriasis and less likely to develop pustular psoriasis. In contrast with psoriasis in adults, psoriasis in children is more likely to involve the face and diaper area. In the diaper area, scaling is often absent.

(Source: The image on the left is from the Massachusetts Medical Society. The image on the right is from Visual Dx.)

Diagnosis

The diagnosis of psoriasis is usually clinical, with special attention paid to the examination of all mucosal areas, nails, and the scalp. Occasionally skin biopsies are needed to assist with the diagnosis.

Types of Psoriasis

Plaque psoriasis: Classically, the lesions are well-circumscribed, pink-to-red, and symmetrically distributed on the extensor surfaces.

Youth with moderate-to-severe plaque psoriasis. (Source: Etanercept Treatment for Children and Adolescents with Plaque Psoriasis. N Engl J Med 2008.)

Guttate psoriasis: Guttate psoriasis presents with multiple teardrop-shaped papules or plaques. It affects up to 30% of pediatric patients with psoriasis and is often the first presentation in children and young adults. The term "guttate" describes the drop-like appearance of the skin lesions. A streptococcal infection has been reported to precede an acute flare of guttate psoriasis in some patients.

Initial eruptions of psoriasis may exhibit a guttate distribution pattern and are often triggered by streptococcal infections. (Source: Psoriasis. N Engl J Med 2005.)

Scalp psoriasis: Psoriasis on the scalp presents as red plaques and scale. It can overlap with seborrheic dermatitis, leading to the terminology “sebopsoriasis.”

Facial psoriasis: Facial psoriasis is more common in children than in adults. In contrast with eczema, psoriasis of the face is better circumscribed and less itchy.

Nail psoriasis: Nail involvement is characterized by the presence of depressions in the nail plate (referred to as “pits”) or yellow-brown discolored spots (referred to as “oil-drop spots”). Thickening of the skin under the nail and splitting of the distal nail plate are common and make the area more vulnerable to secondary infections.

(Source: Nail Pitting in Psoriasis. N Engl J Med 2018.)

Diaper psoriasis: Psoriasis may present in the diaper area in young children. It generally lacks scale and may be difficult to distinguish from other causes of diaper dermatitis and is often resistant to treatment of diaper dermatitis. The sharply defined borders and bright-red color may help distinguish diaper psoriasis from other types of diaper dermatitis.

Comorbidity

Psoriasis has been linked to several other medical conditions. In 2017, guidelines were published for comorbidity screening in patients with pediatric psoriasis. The guidelines are largely in line with general health-screening recommendations endorsed by the American Academy of Pediatrics, with added attention to signs and symptoms of anxiety, arthritis, and depression.

• Comorbidities associated with psoriasis for which routine screening is recommended:

  • overweight and obesity (starting at age 2 years)

  • dyslipidemia (universal screening at ages 9 to 11 years and 17 to 21 years)

  • hypertension (annually starting at age 3 years)

  • anxiety and depression (annually)

  • substance abuse (starting at age 11 years)

• Comorbidities that should be screened for if other risk factors are present:

  • diabetes mellitus (every 3 years starting at age 10 years or puberty if patient is overweight and has two additional risk factors or if obese)

  • nonalcoholic fatty liver disease (if patient is obese or has other risk factors at ages 9 to 11 years)

  • dyslipidemia (screening outside prespecified age ranges if patient has additional cardiovascular risk factors)

• Providers should be aware of comorbidities that may coexist with psoriasis:

  • polycystic ovary syndrome

  • Crohn disease, ulcerative colitis

  • uveitis

Psoriasis may be associated with an inflammatory arthritis. Psoriatic arthritis onset is typically bimodal, most commonly presenting at ages 2 to 3 years and 10 to 12 years. Some studies suggest that 80% of pediatric psoriatic arthritis patients develop arthritis prior to skin psoriasis, which is opposite to the pattern in adults.

Treatment

Multiple modalities can be used for the treatment of psoriasis. See the Joint American Academy of Dermatology-National Psoriasis Foundation guidelines for treatment of pediatric psoriasis.

Topical treatments:

• topical glucocorticoids

• calcineurin inhibitors

• coal tar

• vitamin D analogs

• retinoids

• anthralin

• keratolytics

Systemic treatments:

• systemic retinoids (e.g., acitretin)

• methotrexate

• cyclosporine

• biologic agents (etanercept, ustekinumab, ixekizumab, sekucinumab)

Adjunctive therapies:

• phototherapy

• excimer laser (laser that emits ultraviolet B radiation)