CHOP Protocol

Selection of Foods

  • Careful diet history is obtained. For eosinophilic esophagitis, skin testing and patch testing are sometimes performed to foods that are in child’s diet.
    • In a study of 36 children responsive to an empiric 6 food elimination diet, serial biopsies after food reintroductions showed that the most common causative allergen was milk (74%), wheat (26%), egg (17%), soy (10%), peanut (6%) , and seafood (0%). A single causative food allergen was identified in 72%, 2 foods in 8%, and 3 foods in 8%.
  • Current general screen is: milk, egg, soy, peanut, wheat, rice, corn, oat, barley, potato, beef, chicken, ham, lamb, turkey, pea, green bean, carrot, peach, apple (other foods can also be added)
  • A negative control is included with patch testing (either saline or blank chamber)
  • Patients must be off oral steroids or other systemic immunosuppressants for one month before testing – topical immunosuppressants (protopic, elidel, and topical steroids should not be used at the site for one week prior to application.
  • Example panel:


  • Dry powder foods: milk, egg, soy, wheat, rice, corn, oat, barley, potato: purchased in one pound bags from:, peanut from, or other reliable sources
  • Jarred single ingredient baby foods (pureed): purchased over the counter at grocery stores, Beechnut has no “added” ingredients: beef, chicken, ham, lamb, turkey, peas, green beans, carrot, peach, apple
  • Patches: Finn Chambers, patch trays, patch covers, are available from, Finn chambers are available in two sizes: 8 mm and 12 mm, the selection of foods and size chamber is per the attending physician.
  • Gram scale to weigh powders
  • Sharpie type pen, gauze, applicator, medical tape


  • Weigh out appropriate amounts of foods
    • Dry powders: 1 gram powder in 1 ml sterile water for egg, soy, peanut, wheat, corn, rice, oat, barley, potato
    • 3 grams powder in 1ml for milk— want nice “pasty consistency”
    • Pureed or baby foods (meats, vegetables, fruits): 1 tablespoon onto filter paper to absorb excess fluid
  • Load all prepared foods (except rice and corn-only liquid expels when placed in a syringe) into 3 ml oral syringe, label syringes
  • Place Finn chambers (strip of 10, strip of 5, or single large 12 mm chamber) on patch tray, mark patch strip with the ordered foods (this allows for correct placement and positioning of patches, and for mapping the patches once placed)
  • Place foods into the aluminum discs, enough food to cover the bottom of the disc, either by injecting from syringe, or using a stiff applicator (coffee stirrer, cotton tipped applicator)
  • Milk is always in large Finn chamber
  • Cover the tray and bring into room of patient

Food Patch Test Concentrations.png


  • Have parent or older child remove or lift up clothing to expose back. Locate area on back where there is ample and relatively flat space to apply patches. Clean off selected area on back with alcohol prep pad and let dry.
  • Gently remove the paper from the unexposed covered edge of patch, and place patches on desired location, holding the patch taut immediately prior to application to avoid wrinkling, bulging, buckling of the patch sticker, apply from bottom up
  • Once the patches have been put in place, seal the patch sticker around each well by gently rubbing a finger over the tape surrounding the individual wells, making certain that the wells are sealed by the tape. Tap each well to assure skin contact (48 hours of direct skin contact for results)
  • After all wells have been sealed, take a black Sharpie marker, and place a dot on the skin next to the individual wells.
  • If the patches appear not to be sticking well, medical tape can be applied to help secure the patches to the skin. If taping, make certain that the patches are flat, with all wells in direct contact with the skin.
  • Draw a basic map on the patch testing written record (or other appropriate place in chart) indicating where on the back the patches are, and order of foods on patches.


  • Avoid applying patches on areas such as the scapular edges and places that may undergo a good bit of motion.
  • For older children, have them stand straight with their shoulders back
  • For infants, have the parents hold the child with their faces toward the parent
  • For younger children, have them sit in their parents laps, facing the parent and sit as straight as possible.

Teaching Items for parents

  • Keep child’s back dry until time of patch removal-48 hours minimum from time of application
  • Tell parents the importance of the wells being in direct contact with the skin for 48 hours. If the parent notices that a patch if beginning to come off, re-tape.
  • If areas are pruritic, may treat with antihistamine.
  • After 48 hours, parents will gently remove patches; they will need to get them wet: bath or shower, with lots of warm soapy water, or slather baby oil over patches and skin to help them ”slip” off
  • Encourage parents to leave some of the sharpie marker on the skin, to aide in reading the patch tests.
  • Provide family with day and after hours telephone numbers in case of questions/concerns.
  • Remind families of follow up appointment 72 hours after patch application for patch reading


  • Patches removed 48 hours after patch application, interpreted 72 h after patch application (i.e. 24 h after patches removed)

Skin reaction
No reaction (negative)
Single or scattered red papules with minimal induration------
Solid red with moderate induration
Solid red with significant induration
  • Positive test - grade 1 with 4 papules
  • If saline negative control develops reaction, repeat test in 1 month------

Skin reaction
No reaction (negative)
Single or scattered red papules with minimal induration and erythema
Macular erythema with minimal induration
Significant erythema with vesicles
Significant induration with erythema or significant vesicles with erythema

European Task Force on Atopic Dermatitis
Skin reaction
Only erythema, questionable
Erythema, infiltration
Erythema, few papules
Erythema, many or spreading papules
Erythema, vesicles


  • Document in progress note number of patches placed.
  • Retain order sheet with placement diagram for patch reading in 72 hours