An 8-year-old boy is brought to the emergency department due to a bee sting. The patient's mother reports he was playing in the family's treehouse yesterday when he saw a beehive and tried to knock it down. He received a bee sting to his right hand. His mother removed the stinger and applied ice last night, but upon waking this morning, she noticed the patient's right hand was swollen and mildly painful. He does not report difficulty breathing, vomiting, or swelling of the throat. Temperature is 36.7 C (98.1 F), blood pressure is 110/60 mm Hg, pulse is 98/min, and respirations are 22/min. Pulse oximetry is 100% on room air. The patient is awake and alert, oropharyngeal examination is normal, and lungs are clear to auscultation bilaterally. On the dorsum of his right hand, there is swelling, redness, and induration extending 11 cm from a central clear area. It is painful to make a fist. Perfusion and sensation are intact in his fingers. Which of the following is the most likely cause of this patient's symptoms?

Question

An 8-year-old boy is brought to the emergency department due to a bee sting.  The patient's mother reports he was playing in the family's treehouse yesterday when he saw a beehive and tried to knock it down.  He received a bee sting to his right hand.  His mother removed the stinger and applied ice last night, but upon waking this morning, she noticed the patient's right hand was swollen and mildly painful.  He does not report difficulty breathing, vomiting, or swelling of the throat.  Temperature is 36.7 C (98.1 F), blood pressure is 110/60 mm Hg, pulse is 98/min, and respirations are 22/min.  Pulse oximetry is 100% on room air.  The patient is awake and alert, oropharyngeal examination is normal, and lungs are clear to auscultation bilaterally.  On the dorsum of his right hand, there is swelling, redness, and induration extending 11 cm from a central clear area.  It is painful to make a fist.  Perfusion and sensation are intact in his fingers.  Which of the following is the most likely cause of this patient's symptoms?

Quizplus · Accepted Answer

11ec25c8_d5f1_993a_bc81_ff3f910114a5_MD0003_00 The exaggerated area (~10 cm) of swelling, induration, and redness on this patient's hand after a sting by a member of the Hymenoptera species (eg, bees, yellow jackets, wasps) is called a large local reaction (LLR). Reactions to Hymenoptera envenomation range from mild (1-5 cm or erythema and swelling at the sting site) to severe (anaphylaxis, toxic reactions), with approximately 10% of individuals developing LLR. LLRs, like many allergic responses, are IgE-mediated. Pain, swelling, and erythema begin at the site of the sting within minutes and can progress in size to approximately 10 cm or more. Symptoms usually climax between 24 and 48 hours and resolve over a few days. To be considered an LLR, the area of exaggerated swelling and erythema must be contiguous with the site of the sting. Treatment options include antihistamines, topical or oral steroids, and anti-inflammatory drugs. Patients with LLR may be at higher risk for developing a future systemic reaction (<3%-16%), but prescribing an epinephrine autoinjector remains debatable. (Choice A) Cellulitis is characterized by skin findings similar to LLRs (eg, erythema, warmth, tenderness). However, superinfections are uncommon in insect bites and would generally occur 3-5 days after the initial bite, not within the first 24 hours, as in this patient. (Choice B) Compartment syndrome presents with pain out of proportion, paresthesia, and pain with passive stretch. This patient's mild pain, intact perfusion, and sensation are inconsistent with this diagnosis. Compartment syndrome from insect bites has been reported but is very rare. (Choice D) Lymphangitis occurs when bacteria from a distal site seed the lymphatic channels, causing erythematous, painful streaks in the skin and fever (not seen in this patient). (Choice E) Systemic anaphylaxis is a sudden and life-threatening IgE-mediated response to certain substances. This patient's reaction is IgE-mediated but local, not systemic. Also, systemic symptoms seen in anaphylaxis (eg, vomiting, airway swelling, respiratory difficulty, shock) are absent in this patient. (Choice F) Toxic reactions occur in patients (usually infants or the elderly) who have sustained envenomation from numerous stings by members of the Hymenoptera species. Symptoms (nausea, vomiting, diarrhea, seizures, fever) are due to direct vasoactive properties of the venom. This patient lacks systemic symptoms (eg, no vomiting or fever) and experienced a single sting. Educational objective: Patients with stings from Hymenoptera species can develop exaggerated local allergic responses called large local reactions, characterized by swelling, erythema, and warmth (up to ~10 cm in size) contiguous with the site of the sting. References: Large local reactions and systemic reactions to insect stings: similarities and differences. (http://www.ncbi.nlm.nih.gov/pubmed/32298380)

An 8-Year-Old Boy Is Brought to the Emergency Department Due