CHAPTER 137

Diaper Dermatitis

Houmin Li, MD, PhD; Delphine J. Lee, MD, PhD, FAAD; and Ki-Young Yoo, MD

Diaper dermatitis (DD) is a nonspecific term used to describe the various inflammatory reactions of the skin within the diaper area. Diapered skin is exposed to friction, excessive hydration, and varying pH; additionally, it is in constant contact with urine and stool, both of which are highly irritating to the skin. Management of DD focuses on acceleration of healing of the damaged skin and prevention of a recurring rash. More importantly, the key to efficient DD management is prevention.

Epidemiology

Diaper dermatitis is the most common dermatologic disorder in infancy, with a peak incidence at 9 to 12 months of age, although some reports have shown a high incidence in the first month after birth. The prevalence of reported DD in infants varies greatly, from 7% to 50%. This disorder is not limited to infants and small children; it may occur in any individual who wears diapers, although the prevalence in adults is unknown.

Clinical Presentation

Diaper dermatitis primarily affects the skin of the buttocks, gluteal cleft, lower abdomen, genitalia, perineum, and proximal thighs. The 3 most common types of DD are chafing dermatitis, irritant contact dermatitis, and diaper candidiasis. The different types of DD have distinct clinical presentations. Chafing dermatitis is quite common in infants and appears in areas in which friction from the diaper is most severe. It appears as mild redness in the affected area and improves quickly on its own with frequent diaper changes and/or decreased friction. The most common type of DD, irritant contact dermatitis, appears as scaly erythematous papules and plaques or poorly demarcated, glistening erythema over the convex surfaces, with relative sparing of the intertriginous folds (Figure 137.1A). Diaper candidiasis is another common form of DD and presents as well-defined red plaques with satellite papules and superficial pustules along the margin. Candidal infections may be primarily concentrated within the skin folds (Box 137.1) (Figure 137.1B).

Pathophysiology

The development of all 3 main subtypes of DD is the result of multifactorial interaction, of which the most important is prolonged contact of the skin with urine and stool. Other factors characteristic of the diaper area are excessive moisture, elevated pH, high enzymatic activity, and friction, all of which to some extent compromise the skin barrier function and induce a skin inflammatory reaction.

Prolonged wetness in the diaper area results in maceration of the stratum corneum. Weakening of its physical integrity makes the stratum corneum more susceptible to mechanical friction generated as the diapered infant tries to move, local irritation resulting from chemicals or enzymes, and microbial infections. Urine and stool can elevate the local pH to more alkaline values and in turn cause increased activity of fecal proteases, lipases, and ureases, all of which are highly irritating to the skin. Furthermore, fecal ureases produced by a variety of fecal bacteria catalyze the breakdown of urea to ammonia, which in turn contributes to increased skin pH level. Friction generated as the infant tries to move about may further aggravate the condition and result in maceration of the skin. A damaged skin barrier can also result in microbial imbalance on the skin surface. Candida albicans and Staphylococcus aureus are typically isolated from the affected area and may further aggravate skin inflammation.

Figure 137.1. Diaper dermatitis. A, Diaper dermatitis secondary to irritant contact. Convex surface areas are affected. B, Diaper dermatitis secondary to Candida. Intertriginous areas are affected, and satellite lesions are present.

Differential Diagnosis

Although most cases of DD can be easily recognized clinically, it is important to consider other etiologies beyond the common types mentioned previously, especially when the condition is not responsive to therapy. Familiarity with the difference in appearance of these conditions is critical. The internet can be valuable by providing access to images of many dermatologic conditions. Some websites display a pictorial representation and allow for searching by features such as rash morphologies, symptoms, exposures, skin color, body location, and many other factors.

The differential diagnosis of DD is presented in Box 137.1. Granuloma gluteale infantum is a possible complication of irritant DD that presents with violaceous nodules and plaques on the buttocks, vulva, scrotum, and perineum. Although these nodules and plaques are alarming in appearance, they are benign and will resolve after the dermatitis is cleared; scarring can occur, however. The development of granuloma gluteale infantum does not necessarily correlate with the severity of the preexisting irritant dermatitis. Jacquet erosive dermatitisis another potential complication in which the irritant dermatitis is severe. This form of dermatitis is characterized by small, well-demarcated erosions or ulcers that can also feature elevated borders. With chronic irritant dermatitis, a child may develop perianal pseudoverrucous papules and nodules, which are small bumps characterized by a flat-topped, moist, smooth, shiny surface. All 3 types—granuloma gluteale infantum, Jacquet erosive dermatitis, and perianal pseudoverrucous papules and nodules—are considered to be less common manifestations of irritant contact dermatitis.

Candidiasis, which is the result of infection with C albicans, typically begins in the folds (ie, intertriginous areas) and then spreads to other surfaces. Sometimes associated with oral thrush, candidiasis is also a common sequela of systemic antibiotic therapy. The rash appears as bright, beefy red plaques with sharp, raised borders and many small satellite papules, vesicles, and pustules along its margins, often with desquamation. Candida albicans can be a cause of secondary infection of already inflamed skin as well as a primary causative factor in some cases of DD. Recurrent diaper candidiasis can be associated with candidal colonization of the gut and oral cavity. Persistent diaper candidiasis in young children may be a sign of type 1 diabetes mellitus, chronic mucocutaneous candidiasis, or an underlying immune deficiency.

Seborrheic DD, like candidal DD, also primarily affects the intertriginous areas of the groin. The rash has a characteristic salmon-colored appearance with soft, yellowish scale. Satellite lesions can be seen. Seborrheic dermatitis of the face, scalp (including postauricular areas), neck, trunk, and proximal extremities usually is seen in association with seborrheic dermatitis of the diaper area.

Allergic contact dermatitis is a less common cause of DD but should be considered in patients who do not respond to standard therapeutic interventions. Possible allergens include the chemical makeup of the diaper itself or topical preparations such as soaps, emollients, and baby wipes that are applied to the diaper area. For example, rubber additives (eg, 2-mercaptobenzothiazole) found in the elastics of disposable diapers have been shown to cause allergic DD on the hips and outer buttocks. This distribution is reminiscent of a cowboy’s gun holster, which has earned the condition the moniker “Lucky Luke” dermatitis. Methylchloroisothiazolinone, also known as methylisothiazolinone, is a combination preservative used in personal care and household products and is a common cause of allergic contact dermatitis. Allergic contact dermatitis in the diaper area has been reported with increased frequency in babies on whom wet wipes containing methylisothiazolinone are used. Other allergens to consider are emulsifiers in topical preparations, fragrances, disperse dye, and preservatives.

Bacterial infections can exacerbate DD. Impetigo, especially bullous impetigo, is a not uncommon eruption in the diaper area. Bullous impetigo is caused by S aureus and is toxin mediated. The rash presents as vesicles that may enlarge into 3- to 5-cm (1.2- to 2-in) bullae that easily rupture, leaving superficial erosions with thick, honey-colored crusts. The associated systemic symptoms of fever and diarrhea may be present. Perianal bacterial disease can result from group A β-hemolytic streptococcus or S aureus. Classically, perianal streptococcal dermatitis manifests as well-demarcated, bright red, tender patches. Rectal bleeding and painful defecation may also be noted.

In 30% to 60% of infants born with congenital syphilis, the symptoms are the same as those of DD. Initially, there usually exists a bright erythematous morbilliform eruption that fades to a coppery color, often with scaling. Pustules can develop later. The buttocks, face, extremities, palms, and soles generally are affected.

Diaper rashes that persist despite seemingly adequate therapy should raise suspicion for other systemic diseases as the underlying cause. Though less common than irritant and seborrheic dermatitis and candidiasis, these conditions include psoriasis, atopic dermatitis, zinc deficiency, biotin deficiency, and Langerhans cell histiocytosis. Psoriasis may occur anywhere on the body, but lesions typically occur on the scalp, face, elbows, and knees. In infants, generally between 2 and 8 months of age, psoriasis may involve the diaper area. Lesions elsewhere on the body typically are well-circumscribed, erythematous plaques with a thick, silvery scale. Psoriatic lesions in the diaper area, however, may be difficult to differentiate from seborrheic dermatitis or candidal infection. Plaques are brightly erythematous and sharply demarcated but without obvious scale because of the moisture from the occluded diaper area. Skin biopsy, family history of psoriasis, or nail involvement may help confirm the diagnosis.

Atopic dermatitis typically spares the diaper area, even in infants who have lesions elsewhere on the body. The relative sparing of the diaper area may be a result of the increased moisture of the skin in this area. (See Chapter 138 for a discussion of atopic dermatitis.)

Zinc deficiency can cause dermatitis in a characteristic periorificial distribution (ie, mouth, nose, ears, eyes, and anogenital area) and in the distal extremities. Zinc deficiency may result from the inherited defect acrodermatitis enteropathica or may manifest secondary to insufficient intake or malabsorption, such as in patients with cystic fibrosis. Acrodermatitis enteropathica is a rare, autosomal recessive inherited disorder with mutations in SLC39A resulting in defective zinc transporters in the small intestine. In breastfed infants, the disease manifests shortly after weaning, whereas in bottlefed infants, signs and symptoms appear days to weeks after birth. Afflicted infants are irritable and listless and present with diarrhea, failure to thrive, and skin lesions in the previously mentioned distribution, featuring erythematous bullous and pustular lesions as well as dry, red, scaly plaques. Candidal and S aureus superinfection can occur. Treatment consists of oral zinc supplementation. Biotin deficiency, as well as several other nutritional deficiencies, can present with identical skin findings, and treatment is with supplementation of the deficient nutrient.

Langerhans cell histiocytosis refers to a group of disorders characterized by proliferation of macrophages, a progenitor cell in the bone marrow. Members of this group include Letterer-Siwe disease, Hand-Schüller-Christian disease, eosinophilic granuloma, and congenital self-healing reticulohistiocytosis. Skin lesions may involve the scalp and flexural areas of the perineum, axilla, and neck. The lesions appear as small, pink to tan scaling papules and pustules that can coalesce; associated purpura or ulceration may be apparent in the inguinal fold with secondary impetiginization (ie, honey-colored crusting caused by S aureus superinfection). The rash is most often confused with seborrheic dermatitis. Diagnosis can be confirmed by skin biopsy.

Evaluation

History

A thorough review of the medical history is crucial for efficient diagnosis and management, including duration of the presenting rash, frequency of urination and defecation, other symptoms (eg, pain, itchiness), hygiene practices, and previously used therapies (Box 137.2). Diaper candidiasis should be suspected if oral antibiotic therapy has recently been administered.

Physical Examination

On physical examination, DD presents as an erythematous eruption with varying patterns as described previously. Based on the physical examination of the diaper area and presence of skin lesions elsewhere on the body, potential etiologies should be considered. This is particularly important in the case of a persistent, resistant, or recurrent diaper rash in which a generalized skin disorder, such as psoriasis, must be considered. The distribution of the rash within the diaper area itself may provide clues to the diagnosis. Candidiasis and seborrheic dermatitis occur primarily in the folds, whereas irritant contact dermatitis usually affects the convex areas of the skin with relative sparing of the intertriginous areas. Streptococcal disease manifests primarily as marked perianal erythema.

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