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Pediatric Pearls—From Langerhans to Kawasaki : Consider Langerhans cell histiocytosis in children with refractory atopic or seborrheic dermatitis.


 

WAIKOLOA, HAWAII — Consider Langerhans cell histiocytosis in the child with crusted papules on the palms and soles who has been unsuccessfully treated for scabies or who is mite negative under the microscope, a pediatric dermatology expert suggested.

The diagnosis of Langerhans cell histiocytosis is often delayed for months, sometimes even more than a year, with the lengthiest delays occurring in infants and toddlers. A common reason for the delay is a misdiagnosis of scabies, Dr. Anthony J. Mancini said at the annual Hawaii dermatology seminar sponsored by Skin Disease Education Foundation.

Another reason for delayed diagnosis is that the clinical presentation of Langerhans cell histiocytosis in neonates can differ from that in older children, which is a problem because the disease is more common among neonates than are varicella and neonatal herpes.

Neonates with Langerhans cell histiocytosis can present with hemorrhagic vesiculopustular lesions rather than with the classic scaly, erythematous lesions that occur in older children, according to Dr. Mancini, head of pediatric dermatology at Children's Memorial Hospital, Chicago.

He offered up the following selection of pediatric dermatology clinical pearls, from Langerhans cell histiocytosis to Kawasaki disease:

Langerhans cell histiocytosis. Formerly known as histiocytosis X, this disorder ranges in severity from a benign and self-limited condition to a disseminated disease with severe morbidity and even mortality. The skin and bones are the most commonly involved sites. Other sites include the GI tract, lungs, spleen, CNS, liver, and endocrine glands.

A common theme of Langerhans cell histiocytosis in the skin is discrete superficial papular or nodular erosions in flexural folds. The papules are brown to red in color and may be flat topped, especially in infants. Consider the possibility of Langerhans cell histiocytosis in children with refractory atopic or seborrheic dermatitis.

"Don't hesitate to get a biopsy," Dr. Mancini urged.

Streptococcal intertrigo. Think of group A β-hemolytic streptococci in children with fiery-red intertrigo with a foul smell, erosive lesions, and an absence of the satellite lesions typical of Candida albicans intertrigo.

Streptococcal intertrigo responds quickly to treatment with a low-potency, topical corticosteroid for the inflammation, moist compresses two or three times per day, perhaps a topical antifungal agent to address the Candida, and, most importantly, a systemic antibiotic that covers both group A β-hemolytic streptococci and possible coinfection with Staphylococcus aureus.

"Your first choice here should be something simple, like cephalexin given t.i.d. for 10 days," said Dr. Mancini.

Serum sickness-like reactions. These drug reactions can occur 1–3 weeks after starting any of a number of antibiotics or griseofulvin, and are not true serum sickness because there are no circulating immune complexes. Fever and swollen lymph nodes occur less often than in true serum sickness, and proteinuria is rare.

The cutaneous hallmark of serum sickness-like reactions is erythema progressing to purple urticaria with dusky centers. The lesions tend to be transient and migratory. The child will have periarticular swelling, arthralgia, and a reduced range of motion. Refusal to ambulate is a key feature.

Treatment consists of the withdrawal of the offending drug and a prescription for a nonsteroidal anti-inflammatory agent and for corticosteroids, Dr. Mancini said at the meeting.

Herpes-associated erythema multiforme. Don't hesitate to suppress this disease, both to prevent the painful and unsightly lesions of erythema multiforme and to head off mucous membrane involvement, and because treatment may prevent Stevens-Johnson syndrome.

Acyclovir gets the nod here because it is approved for use in children; famciclovir and valacyclovir are not. "I like the acyclovir oral suspension; it's really well tolerated in kids," Dr. Mancini said. He prescribes 1/2 teaspoon (100 mg) twice daily in children younger than 2 years old, 150 mg twice daily in children aged 2–6 years, and a full teaspoon twice daily in those older than 6 years.

The appropriate duration of therapy to suppress herpes-associated erythema multiforme is unclear. He recommends a minimum of 6 months of daily acyclovir, then a taper to a trial off therapy. In some cases, treatment needs to continue for years. "This is an art, not a science," the dermatologist stressed.

Kawasaki disease. This disease is the leading cause of acquired heart disease in patients under 5 years of age. Formal diagnosis requires the presence of any five of these six symptoms: unexplained high fever lasting more than 5 days; cervical adenopathy in excess of 1.5 cm; nonpurulent conjunctival infection; swelling of the extremities; oropharyngeal changes; and a polymorphous skin eruption.

Coronary artery aneurysms also can occur with incomplete Kawasaki disease, marked by high fever plus as few as one or two of the other criteria. This occurs more commonly in infants.

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