Rashes in the diaper area are common in babies between the ages of 7 and 12 months. Most cases will clear with frequent diaper changes and the use of superabsorbent disposable diapers. The differential diagnosis includes mainly seborrheic dermatitis, candidiasis, irritant contact dermatitis, atopic dermatitis and psoriasis. In cases with an atypical presentation, recurrence, or resistance to usual treatments, one should consider less common diagnoses such as histiocytosis; referral to a dermatologist and a biopsy may be necessary at the time.

It is very important to consider the diagnosis of contact dermatitis. The use of colored topical agents is strongly inadvisable because they may mask lesions and prevent semiological analysis.

Based on the Localization of the Dermatitis
One Can Distinguish

‘Y’ diaper dermatitis: The ‘Y’ refers to involvement of the folds (inguinal and gluteal folds) which are erythematous, inflammatory and macerated.

These lesions may be isolated or associated with satellite vesicular, pustular or papular lesions extending beyond the folds. Sometimes the ‘Y’ intertrigo is associated with involvement of other folds (groin, retroauricular, or axillae folds) which are manifestations of seborrheic dermatitis. More often, there is neither diarrhea nor oral candidiasis. Treatment includes gentle washing, careful drying, frequent diaper changes, and topical applications (twice a day for 15 days) of an antifungal cream as these lesions are frequently complicated by secondary infection with Candida albicans. If the eruption is recalcitrant, or if it lasts for more than 10 days, Langherans’ histiocytosis has to be considered (see later).

‘W’ diaper dermatitis (fig. 1): The ‘W’ refers the involvement of convex surfaces (convexities of the buttocks, upper thighs, etc.), with sparing of the folds. Most often, the skin is red and dry. This is an ‘irritant contact dermatitis’, due to maceration and wetness. Treatment consists of careful washing and drying, with frequent diaper changes. This type of diaper dermatitis may have to be differentiated from acrodermatitis enteropathica (see later).

‘Mixed diaper dermatitis’: Most often, diaper dermatitis is mixed: folds are more or less involved, and there are some maculo-papular rashes on the convexities.

In these cases, etiology is often multifactorial (primary irritant dermatitis secondarily infected with bacteria and Candida). Allergic contact dermatitis is infrequent in the diaper area.

Jacquet erosive diaper dermatitis is defined primarily as an irritant diaper dermatitis (home washing of cloth diapers and insufficiently frequent diaper changing). It looks like a well-demarcated diaper dermatitis with punched-out ulcers or erosions with elevated borders (pseudoverrucous papules) on the labia majora. Because of improvements in disposable diaper material, this disease today has become extremely rare. It only may be observed in cases of prolonged maceration seen with urinary incontinence and/or prolonged severe diarrhea. Symptomatic treatment is required.

Lucky-Luke diaper dermatitis is a diaper dermatitis with a particular topography recalling the cowboy’s pistol belt handles: erythema occurs in the area of the elastic band due to the rubber component.

Other Etiologies Are Less Systematic in Their Location
Children with atopic dermatitis may have a rash in the diaper area. Papular or microvesicular erythematous lesions may be present, most often localized on the upper thighs and convex surfaces. Treatment of atopic dermatitis in the napkin area should not include topical steroids, because of the well-known risk of granuloma gluteale infantum with atrophic scars.

Psoriasis can present as well-demarcated, red, non-scaly symmetrical plaques which extend from the vulva to the perianal area, natal cleft, inguinal folds, and mons pubis (

fig. 2). The vagina is not involved. The rest of the skin may appear spared, until one searches for nail pitting or scalp or post-auricular erythema. There is often a positive family history. The relationship to psoriasis in later life is uncertain.