Patch testing tricks in atopic dermatitis with concomitant contact dermatitis

COEUR D’ALENE, IDAHO– Contact dermatitis goes together with moderate-to-severe atopic dermatitis like ham and eggs. Reading patch test results in such patients poses unique challenges, because of the impaired skin barrier function intrinsic to atopic dermatitis, coupled with the moist environment created under the occlusive patches, which predisposes to Staphylococcus aureus colonization and superinfection.

All of this makes the evaluation of patch test results in atopic dermatitis more complicated than in patients without contact dermatitis. But there are tricks that greatly reduce the difficulty.

"Patch testing can play a crucial role in the work-up and management of patients with refractory atopic dermatitis. Prior to patch testing, measures should be taken to improve the skin barrier and reduce bacterial overload," Dr. Sharon E. Jacob advised at the annual meeting of the Society for Pediatric Dermatology.

Her recommended preparation program starts 3 weeks prior to the scheduled patch test. The emphasis is on beefing up the disrupted skin barrier through the use of lipid-replenishing emollients and nonalkaline soaps, avoidance of fragrances and other irritant allergens, and preemptive treatment of S. aureus colonization or superinfection, explained Dr. Jacob of Loma Linda (Calif.) University.

At the start of the 3-week countdown, a patient with no clinical signs of skin infection should be checked for nasal carriage of S. aureus. If positive, or if the patient has a remote history of S. aureus colonization or superinfection but no current signs of colonization, such as oozing or crusting, it’s appropriate to begin intranasal, perianal, and umbilical topical mupirocin twice daily for 5 days.

It’s also time to eliminate irritant allergens, start a regimen of dilute bleach baths, embrace the special emollients and soaps, and make sure areas of dermatitis are getting adequately treated with topical steroids, except for the planned patch test area, which must remain steroid free for 7 days prior to the test day.

The lipid-containing emollients, which should contain ceramides or filaggrin degradation products, are to be used all over the body, including the back, until the day before the test.

Examples of the nonalkaline soaps, which are employed to maintain an acidic skin pH, include Aveeno Moisturizing Bar soap, Cetaphil Gentle Cleansing Bar, and Dove Sensitive Skin Unscented Beauty Bar, the pediatric dermatologist continued.

Patients on UV phototherapy for their atopic dermatitis can continue except at the planned patch test site, where it should be avoided for 2 weeks beforehand.

In an adolescent with head and neck atopic dermatitis, a pre–patch test course of oral antifungal therapy is worth considering, according to Dr. Jacob.

For the atopic dermatitis patient with clinical signs of bacterial infection at the pre–patch test office visit, culture the lesions and start a preemptive 10-day course of oral cephalexin at 25-50 mg/kg per day three times daily beginning 3 days prior to patch testing, with the choice of antimicrobial adjusted as warranted by the culture results. These patients also go on the emollients, soaps, dilute bleach baths, and irritant allergen avoidance regimen.

A patient with no signs of skin infection when the test patches are removed can continue with the test readings as scheduled, with no further intervention. However, if signs of infection are present, the patient should immediately go on oral cephalexin if not already on it and take a single bleach bath the same day the patches come off. The bath should be at one-tenth to one-half the customary concentration of 0.005% sodium hypochlorite and should be followed by a fresh water rinse.

The usual patch test reading schedule in atopic dermatitis patients is at 24-48 hours, again at 72-96 hours, and once again at 120 hours. That last reading is vital because patients with atopic dermatitis can have a low irritant threshold; the delayed reading lessens the possibility of reading irritant reactions as positives.

The reading at 72-96 hours is the time for induration testing.

"When evaluating patch test reactions, palpation for induration is absolutely necessary," Dr. Jacob emphasized. "First the evaluator palpates the baseline dermatitis, and then the patch application squares, looking for areas of increased induration and effectively subtracting background."

She reported serving as a consultant to Johnson & Johnson and Medimetriks and as a clinical investigator for SmartPractice, which manufactures patch test kits, the use of which remains nonapproved by the Food and Drug Administration in children.

[email protected]

COEUR D’ALENE, IDAHO– Contact dermatitis goes together with moderate-to-severe atopic dermatitis like ham and eggs. Reading patch test results in such patients poses unique challenges, because of the impaired skin barrier function intrinsic to atopic dermatitis, coupled with the moist environment created under the occlusive patches, which predisposes to Staphylococcus aureus colonization and superinfection.

All of this makes the evaluation of patch test results in atopic dermatitis more complicated than in patients without contact dermatitis. But there are tricks that greatly reduce the difficulty.

"Patch testing can play a crucial role in the work-up and management of patients with refractory atopic dermatitis. Prior to patch testing, measures should be taken to improve the skin barrier and reduce bacterial overload," Dr. Sharon E. Jacob advised at the annual meeting of the Society for Pediatric Dermatology.

Her recommended preparation program starts 3 weeks prior to the scheduled patch test. The emphasis is on beefing up the disrupted skin barrier through the use of lipid-replenishing emollients and nonalkaline soaps, avoidance of fragrances and other irritant allergens, and preemptive treatment of S. aureus colonization or superinfection, explained Dr. Jacob of Loma Linda (Calif.) University.

At the start of the 3-week countdown, a patient with no clinical signs of skin infection should be checked for nasal carriage of S. aureus. If positive, or if the patient has a remote history of S. aureus colonization or superinfection but no current signs of colonization, such as oozing or crusting, it’s appropriate to begin intranasal, perianal, and umbilical topical mupirocin twice daily for 5 days.

It’s also time to eliminate irritant allergens, start a regimen of dilute bleach baths, embrace the special emollients and soaps, and make sure areas of dermatitis are getting adequately treated with topical steroids, except for the planned patch test area, which must remain steroid free for 7 days prior to the test day.

The lipid-containing emollients, which should contain ceramides or filaggrin degradation products, are to be used all over the body, including the back, until the day before the test.

Examples of the nonalkaline soaps, which are employed to maintain an acidic skin pH, include Aveeno Moisturizing Bar soap, Cetaphil Gentle Cleansing Bar, and Dove Sensitive Skin Unscented Beauty Bar, the pediatric dermatologist continued.

Patients on UV phototherapy for their atopic dermatitis can continue except at the planned patch test site, where it should be avoided for 2 weeks beforehand.

In an adolescent with head and neck atopic dermatitis, a pre–patch test course of oral antifungal therapy is worth considering, according to Dr. Jacob.

For the atopic dermatitis patient with clinical signs of bacterial infection at the pre–patch test office visit, culture the lesions and start a preemptive 10-day course of oral cephalexin at 25-50 mg/kg per day three times daily beginning 3 days prior to patch testing, with the choice of antimicrobial adjusted as warranted by the culture results. These patients also go on the emollients, soaps, dilute bleach baths, and irritant allergen avoidance regimen.

A patient with no signs of skin infection when the test patches are removed can continue with the test readings as scheduled, with no further intervention. However, if signs of infection are present, the patient should immediately go on oral cephalexin if not already on it and take a single bleach bath the same day the patches come off. The bath should be at one-tenth to one-half the customary concentration of 0.005% sodium hypochlorite and should be followed by a fresh water rinse.

The usual patch test reading schedule in atopic dermatitis patients is at 24-48 hours, again at 72-96 hours, and once again at 120 hours. That last reading is vital because patients with atopic dermatitis can have a low irritant threshold; the delayed reading lessens the possibility of reading irritant reactions as positives.

The reading at 72-96 hours is the time for induration testing.

"When evaluating patch test reactions, palpation for induration is absolutely necessary," Dr. Jacob emphasized. "First the evaluator palpates the baseline dermatitis, and then the patch application squares, looking for areas of increased induration and effectively subtracting background."

She reported serving as a consultant to Johnson & Johnson and Medimetriks and as a clinical investigator for SmartPractice, which manufactures patch test kits, the use of which remains nonapproved by the Food and Drug Administration in children.

[email protected]

COEUR D’ALENE, IDAHO– Contact dermatitis goes together with moderate-to-severe atopic dermatitis like ham and eggs. Reading patch test results in such patients poses unique challenges, because of the impaired skin barrier function intrinsic to atopic dermatitis, coupled with the moist environment created under the occlusive patches, which predisposes to Staphylococcus aureus colonization and superinfection.

All of this makes the evaluation of patch test results in atopic dermatitis more complicated than in patients without contact dermatitis. But there are tricks that greatly reduce the difficulty.

"Patch testing can play a crucial role in the work-up and management of patients with refractory atopic dermatitis. Prior to patch testing, measures should be taken to improve the skin barrier and reduce bacterial overload," Dr. Sharon E. Jacob advised at the annual meeting of the Society for Pediatric Dermatology.

Her recommended preparation program starts 3 weeks prior to the scheduled patch test. The emphasis is on beefing up the disrupted skin barrier through the use of lipid-replenishing emollients and nonalkaline soaps, avoidance of fragrances and other irritant allergens, and preemptive treatment of S. aureus colonization or superinfection, explained Dr. Jacob of Loma Linda (Calif.) University.

At the start of the 3-week countdown, a patient with no clinical signs of skin infection should be checked for nasal carriage of S. aureus. If positive, or if the patient has a remote history of S. aureus colonization or superinfection but no current signs of colonization, such as oozing or crusting, it’s appropriate to begin intranasal, perianal, and umbilical topical mupirocin twice daily for 5 days.

It’s also time to eliminate irritant allergens, start a regimen of dilute bleach baths, embrace the special emollients and soaps, and make sure areas of dermatitis are getting adequately treated with topical steroids, except for the planned patch test area, which must remain steroid free for 7 days prior to the test day.

The lipid-containing emollients, which should contain ceramides or filaggrin degradation products, are to be used all over the body, including the back, until the day before the test.

Examples of the nonalkaline soaps, which are employed to maintain an acidic skin pH, include Aveeno Moisturizing Bar soap, Cetaphil Gentle Cleansing Bar, and Dove Sensitive Skin Unscented Beauty Bar, the pediatric dermatologist continued.

Patients on UV phototherapy for their atopic dermatitis can continue except at the planned patch test site, where it should be avoided for 2 weeks beforehand.

In an adolescent with head and neck atopic dermatitis, a pre–patch test course of oral antifungal therapy is worth considering, according to Dr. Jacob.

For the atopic dermatitis patient with clinical signs of bacterial infection at the pre–patch test office visit, culture the lesions and start a preemptive 10-day course of oral cephalexin at 25-50 mg/kg per day three times daily beginning 3 days prior to patch testing, with the choice of antimicrobial adjusted as warranted by the culture results. These patients also go on the emollients, soaps, dilute bleach baths, and irritant allergen avoidance regimen.

A patient with no signs of skin infection when the test patches are removed can continue with the test readings as scheduled, with no further intervention. However, if signs of infection are present, the patient should immediately go on oral cephalexin if not already on it and take a single bleach bath the same day the patches come off. The bath should be at one-tenth to one-half the customary concentration of 0.005% sodium hypochlorite and should be followed by a fresh water rinse.

The usual patch test reading schedule in atopic dermatitis patients is at 24-48 hours, again at 72-96 hours, and once again at 120 hours. That last reading is vital because patients with atopic dermatitis can have a low irritant threshold; the delayed reading lessens the possibility of reading irritant reactions as positives.

The reading at 72-96 hours is the time for induration testing.

"When evaluating patch test reactions, palpation for induration is absolutely necessary," Dr. Jacob emphasized. "First the evaluator palpates the baseline dermatitis, and then the patch application squares, looking for areas of increased induration and effectively subtracting background."

She reported serving as a consultant to Johnson & Johnson and Medimetriks and as a clinical investigator for SmartPractice, which manufactures patch test kits, the use of which remains nonapproved by the Food and Drug Administration in children.

[email protected]