2025 – PAGE 101 – ALLERGY & IMMUNOLOGY

(DOUBLE TAKE) ATOPIC DERMATITIS (ECZEMA)

In babies, atopic dermatitis (eczema) SPARES the diaper folds/flexural surfaces (but not in older kids). It is PRURITIC and LICHENIFIED. Food allergies CAN exacerbate eczema. The contribution of early food ingestion to the development of atopic dermatitis is controversial. Eggs, fish, milk, peanut, soy, wheat and strawberries are the foods thought to possibly contribute, but delaying their introduction doesn’t help. Positive skin and RAST tests for foods are not predictive, either. Treatment options include emollients and topical steroids. Avoid use of steroids in areas where the skin is thin. Use the lowest potency steroids that work. Non-steroidal treatment options include topical calcineurin inhibitors (tacrolimus and pimecrolimus) and topical PDE4 inhibitors (crisaborole). Non-steroidal treatments are preferred for the face. Watch for superinfection if the eczema is not improving with appropriate therapy.

IMAGE: www.pbrlinks.com/ECZEMA1

URTICARIA (HIVES)

Urticaria (hives) refers to a skin rash usually consisting of pale red, raised, itchy bumps. It might be associated with burning or stinging and is caused by either an allergy (IgE mediated due to food, insect sting, drug, or environmental allergies) or a non-allergic cause (non-IgE mediated due to viral infection and others). Urticaria due to an allergic cause can last hours, while urticaria due to non-allergic causes can last up to 6 weeks. Viruses are the most common cause of acute urticaria lasting more than 1 day. Food allergies usually cause acute urticaria within 1 hour and usually last for only a few of hours. If urticaria is noted as an isolated skin manifestation (with or without angioedema), you do NOT have to administer epinephrine. You MUST give epinephrine if there is also ANY associated breathing-related symptom (coughing, wheezing or any evidence of airway compromise) or any other systemic symptoms (nausea, vomiting, abdominal pain, or circulatory system compromise) to suggest anaphylaxis. Such cases should be referred to an allergist because of the possible need for venom immunotherapy.

CHRONIC URTICARIA (> 6 weeks)

Chronic urticaria must be present either intermittently or continuously for at least 6 weeks and is most often idiopathic in nature. Other causes can include autoimmune diseases (SLE, JIA, dermatomyositis, Sjogren syndrome), immune complex mediated processes (serum sickness), chronic viral/bacterial/parasite infections (H. pylori, helminthic parasitic infections, HBV, HCV, EBV, HSV), or neoplasms (lymphoproliferative disorders). Chronic urticaria is typically NOT due to an allergic trigger and it is rarely associated with a life-threatening condition. It can occur at any time of the day or night.

PEARL: Recurrent angioedema in the absence of urticaria should be evaluated for hereditary angioedema.

(DOUBLE TAKE) C1 ESTERASE DEFICIENCY (HEREDITARY ANGIOEDEMA)

C1 esterase deficiency results in hereditary angioedema, in which there are recurrent episodes of swelling/edema and abdominal pain.

PEARL: These patients do NOT have pruritis.

ARTIFICIAL FOOD COLORING

Artificial food coloring does NOT cause urticaria. Old reports were based on poor studies.

(DOUBLE TAKE) ANAPHYLAXIS

Anaphylaxis is a serious allergic reaction that is rapid in onset and may cause death according to the NIH and the Food Allergy & Anaphylaxis Network. The criteria generally require TWO systems to be affected in order to qualify for the definition of anaphylaxis. The one exception is when there is acute hypotension (may be evidenced by hypotonia or syncope), in which case the single finding can be used to define anaphylaxis. The four systems that can be affected minutes to hours after exposure to a suspected allergen include:

• Skin or mucosal involvement: Considered one system. Look for hives, itching, flushing or edema.
• Respiratory system: Look for wheezing, stridor, hyposmia or coughing.
• Continued GI symptoms: Look for vomiting or abdominal pain.
• Circulatory system compromise: Look for hypotension as evidenced by hypotonia, syncope or a drop in systolic blood pressure of > 30% (or a systolic blood pressure that is below the 70 mmHg + the child’s age in years).

The following is a review of some common issues to be aware of in case a child presents with anaphylaxis:

• FOOD EXPOSURE: Monitor for four hours for signs of rebound anaphylaxis after initial treatment. Children can potentially be monitored at home if they have a second dose of epinephrine available at home.
• RESPIRATORY COMPROMISE: When anaphylaxis is diagnosed, epinephrine should be given immediately in order to avoid respiratory compromise. If respiratory compromise already exists, then focus on securing the airway first and THEN focus on giving EPInephrine (1:1000, “3 zeroes for 3 letters of EPI”), diphenhydramine, IVF, and steroids.
• BETA BLOCKERS: They blunt the response to EPInephrine. Give glucagon to reverse the beta blocker effect and then give EPInephrine (again).
• ANAPHYLACTOID REACTIONS result from mast cell degranulation. These are not true IgE-mediated reactions. They may be seen with the use of NSAIDS, opiates, contrast, and vancomycin (in vancomycin flushing reaction, previously known as red man syndrome). Pretreat with steroids and diphenhydramine.