Joel Schwab M.D.

Urticaria or hives is an evanescent rash often preceded by itching that can occur on any part of the body. The lesions are raised, pinkish-white patches(wheals) that can occur on any part of the body. They are usually well circumscribed but may be coalescent and will blanch with pressure. Eruptions may evolve quickly over minutes to hours and hey typically last less than 4 hours but they may stay for days or weeks. Approximately 20% of the population has experienced a bout of hives. 

Hives are secondary to edema of the stratum corneum related to vascular dilatation and increased capillary permeability. Angioedema is caused by a similar mechanism but involves deeper layers of the skin and subcutaneous tissue. There is non-pitting, non-dependent, edema. Angioedema commonly affects the gastrointestinal tract, upper respiratory tract, and the tissues around the eyes. If the airway is involved, it may be life threatening.

Pathogenesis

1. Immunologic-  IgE on mast cells bind to antigens leading to degranulation and histamine release. This increases capillary permeability
2. Non Immunologic
1. Activation of the complement system (C3a, C4a, C5a) may trigger release of histamine. Associated with opioids and NSAIDs.
2. Plasma kinin forming system leading to histamine release
3. Physical forces may lead to release of histamine

1. Idiopathic -85% of cases no etiology is identified.
2. Allergic
1. Antibiotics- Penicillin, Cephalasporins, Sulfas. May occur during or after completion of taking drug. May take weeks to resolve.
2. Bee stings may cause local reaction
3. Inhalants- animal dander, pollen, feathers
4. Contact
5. Food- milk, egg whites, peanuts, shellfish, and fish
6. mosquito and flea bites
3. Non-allergic
1. Stress
2. Viral infections- hepatitis, EBV
3. Dermatographia
4. Heat and cold- usually to exposed area only like after putting on ice pack to an area
5. Sun exposure
6. Pressure- around area of tight clothes
7. Vibration
8. Aquagenics
4. Hereditary Angioedema. Autosomal dominant and there is a deficiency of C1q esterase inhibitor which leads to higheer levels of activated complement.
   
5. Associated with systemic diseases- SLE, ALL, Lymphoma, endocrinopathies 
6. Urticaria pigmentosa- Darier's sign.  Rubbing of the pigmented lesion will lead to wheal formation.
   

1. History with emphasis on drugs, diet, and previous bouts of hives
   
2. Have patient or family keep a diary of when hives occur and what medications were taken, foods eaten, and activities.
3. No further workup necessary unless suspect underlying systemic disease. 

1. Avoidance of specific drug, food, or activity
2. If there is a severe reaction or angioedema of the airway, may use epinephrine(1:1000) The dose is 0.01ml/kg.with maximum of 0.3ml. 
3. Antihistamines- Atarax, Benadryl,Tavist, Claritin
4. In rare instances, systemic steroids may be useful.
5. Compassion and reassurance 

1. Eitches, Robert. Urticaria: A wheal of misfortune. Contemporary Pediatrics. June 1993.
2. Weston WL. Urticaria. Pediatrics in Review. 1998; 19:240-244.
3. Plumb J, et al. Exposures and Outcomes of Children with Urticaria Seen in a Pediatric Practice-Based Research Network.  Archives of Pediatrics and Adolescent Medicine. Sept. 2001
4. Leickly F. When the road gets bumpy: Managing chronic urticaria. Contmeporary Pediaatirics May 2000
5. Alangari A. .Clinical Feataures of Children with Cold Urticaria Pediatrics 2004 April e-313
6. Sacksen C. et al. The Etiology of Different forms of Urticaria in Childhood.  Pediatr Dermatol. 2004; 21(2) 102
7. Hernandez R, Cohen B.Insect Bite Induced Hypersensitivity and The SCRATCH Principles: A New Approach to Papular Urticaria.  Pediatrics 2006;118 e189-196
8. Sardina N, Craig T.  Recent Advances in Management and Treatment of Hereditary Angioedema.  Pediatrics December 2011