Differential diagnoses for Pediatric Pruritic Rash

A generalized pruritic rash in a child may have any of a number of causes, ranging from autoimmune problems, allergies, infections and infestations, endocrine and metabolic disorders, and inflammations (Cleveland Clinic, 2010). Thus, one key to distinguishing among these various outcomes is to identify the timing of flare-ups. In children, several potential diagnoses of a generalized pruritic rash may include (Xia, Davies & Gunning, 2008):

• Scabies—rash usually on finger webs, wrists, elbows, axillae, buttucks and extremely pruritic; rash is inflammatory papules, or nodules or excoriations.
• Papular urticaria—usually not on genital, periana, or axillary areas of the body, intensely pruritic, and the rash usually appears in linear clusters.
• Lichen planus –rash usually on the wrists, shins, scalp, lumbar region, penis, or other mucous membranes, and is intensely pruritic; the rash is usually pink to violet, shiny and polygonal with white scales.

Other potential causes for pediatric pruritic rashes include allergic contact dermatitis (any age; but flare-ups happen after contact with an allergen), eczema (children of any age, sometimes associated with asthma and hay fever), and dermatitis herpetiformis (older children and young adults and often accompanied by gastrointestinal symptoms); those patients with scabies may be the result of social contact with other infected individuals in their classroom, family, or play groups (Cunliffe, 2006).

With so many potential sources of a generalized pruritic rash, these are clearly not the only possible diagnoses.

Treatment of diagnoses

Treatment varies according to the suspected underlying cause of the rash. Suggested treatments for the above causes include (Cunliffe, 2006):

• Eczema: Use a topical steroid—the lowest dosage that deals with the rash—allowing it to dry before following it with lots of moisturizing lotions. If the rash is on the face, try a topical pimecrolimus cream instead; patients should also avoid sun exposure (Cunliffe, 2006).
• Scabies: Everyone in the household should be treated for scabies with 5% permethrin from the neck down on every inch of the skin, including under the nails, and leave on for12 to 24 hours before bathing. Towels and bed linens should be washed in hot water and dried in a dryer; the infected person should repeat the treatment in four days (Cunliffe, 2006).
• Lichen planus: Use potent or very potent topical steroids are effective and they should be used only if the symptoms are severe; the side effects are significant and include skin atrophy; if symptoms are widespread or include the genital area, a specialist is needed (Cunliffe, 2006).
• Dermatitis herpetiformis: These patients should be referred for specialist care (Cunliffe, 2006).
• Papular urticaria: If an antihistamine is not effective, full blood work is needed; these patients should avoid aspirin and NSAIDs, and in children desloratadine is recommended (Cunliffe, 2006).
• Allergic contact dermatitis: In this case, once the allergen has been identified, the main treatment is to avoid contact with that allergen and apply a topical steroid (Uhlenhake, 2009). For example, a leading allergen is nickel, present in eyeglass frames, inexpensive jewelry, rivets in jeans, and even cell phones (Uhlenhake, 2009).