What is the likely diagnosis and acute management for a 72-year-old man with mild bilateral lower‑leg edema and facial angioedema after eating goat intestine and drinking beer?

Likely Diagnosis and Acute Management

This 72-year-old man is experiencing food-induced anaphylaxis, and immediate intramuscular epinephrine administration is mandatory, followed by emergency department observation for at least 4-6 hours. The combination of bilateral lower limb edema and facial angioedema occurring within minutes to hours after consuming goat intestine and beer meets established diagnostic criteria for anaphylaxis 1.

Diagnostic Reasoning

The presentation fulfills anaphylaxis criteria because it involves two or more organ systems (skin/mucosal tissue with angioedema and potential cardiovascular involvement with peripheral edema) occurring rapidly after food exposure 1. Key diagnostic features include:

• Cutaneous manifestations occur in 80-90% of anaphylaxis cases and include angioedema, which is present in this patient 1
• Cardiovascular symptoms occur in up to 35% of cases and can manifest as peripheral edema from fluid shifts and hypotension 1
• The 72-year-old age places him in a high-risk category, as cardiovascular disease is an important risk factor for death from anaphylaxis in middle-aged and older individuals 1

Critical Differential Considerations

Hereditary angioedema (HAE) is unlikely because this patient has no documented family history of angioedema, normal C1-INH function would be expected, and the temporal relationship to food ingestion strongly suggests IgE-mediated mechanisms 1, 2, 3. HAE typically presents with episodic attacks not consistently triggered by specific foods 1.

ACE inhibitor-induced angioedema must be excluded by medication history, as it classically presents with facial and oral cavity swelling without urticaria, though the temporal relationship to food makes this less likely 2, 3, 4.

Immediate Management Protocol

First-Line Treatment

Administer epinephrine 0.3-0.5 mg intramuscularly into the mid-outer thigh immediately 1, 5. This is non-negotiable even in elderly patients with cardiovascular disease, because:

• The risk of death from untreated anaphylaxis outweighs concerns about cardiac effects, and myocardial ischemia can occur from anaphylaxis itself 1
• Deaths from food-induced anaphylaxis occur within 30 minutes to 2 hours due to cardiorespiratory compromise 1, 6
• Delayed epinephrine administration is the primary factor associated with fatal outcomes 1
• No absolute contraindications exist for epinephrine in anaphylaxis 1, 7

Adjunctive Measures

After epinephrine administration:

• Position the patient supine with legs elevated to counteract hypotension and improve venous return 1
• Administer H1 antihistamine (diphenhydramine) and H2 antihistamine (ranitidine) to reduce urticaria and angioedema, though these do NOT treat the underlying anaphylaxis 1, 7
• Give systemic corticosteroids (prednisone or methylprednisolone) to potentially reduce biphasic reactions, which occur in 1-20% of cases typically 8 hours later but can occur up to 72 hours after initial symptoms 1, 6
• Monitor vital signs continuously, as tachycardia without hypotension may indicate compensated shock 1, 6

Critical Medication History

Immediately assess for medications that increase anaphylaxis risk or blunt epinephrine response 1:

• β-adrenergic antagonists decrease response to epinephrine and may require higher or repeated doses 1
• ACE inhibitors and angiotensin II receptor blockers interfere with compensatory mechanisms, resulting in more severe or prolonged symptoms 1
• α-adrenergic blockers decrease epinephrine effectiveness at α-receptors 1

Emergency Department Management

Transfer to an emergency facility for observation of 4-6 hours minimum, with prolonged observation or admission for severe symptoms 1. During observation:

• Monitor for biphasic reactions, which can occur without warning after apparent resolution 1, 6
• Repeat epinephrine every 5-15 minutes if symptoms persist or progress 1
• Prepare for airway management if facial angioedema progresses to laryngeal involvement 1, 8

Diagnostic Workup After Stabilization

Laboratory testing has limited value during acute anaphylaxis but should be pursued after stabilization 1:

• Serum tryptase is typically NOT elevated in food-induced anaphylaxis and lacks specificity 1
• Skin prick testing or serum-specific IgE to goat meat proteins, alcohol additives, and common food allergens (if beer contained food proteins) should be performed 4-6 weeks after the acute event 1, 9
• Oral food challenge remains the gold standard for confirming clinical allergy but must only be performed in a controlled setting with resuscitation equipment available 9, 7

Discharge Planning

Before discharge, the patient must receive 1:

• Epinephrine auto-injector prescription with hands-on training for proper administration technique 1, 9
• Continuation of adjunctive medications: H1 antihistamine every 6 hours for 2-3 days, H2 antihistamine twice daily for 2-3 days, and oral corticosteroid daily for 2-3 days 1
• Medical alert identification (bracelet or wallet card) indicating food allergy and anaphylaxis risk 1
• Strict avoidance instructions for goat meat and potentially cross-reactive mammalian meats until allergy evaluation is complete 1, 7
• Referral to allergist/immunologist for comprehensive evaluation and long-term management 1

Common Pitfalls to Avoid

Do not withhold epinephrine because the patient appears stable or symptoms seem mild—anaphylaxis can progress rapidly to fatal airway obstruction or cardiovascular collapse 1, 6.

Do not rely on absence of urticaria to exclude anaphylaxis, as 10-20% of cases have no cutaneous manifestations beyond angioedema 1, 6.

Do not discharge the patient without extended observation, as biphasic reactions can occur hours after apparent resolution 1, 6.

Do not assume this is a first-time reaction—anaphylaxis can occur at any age with first exposure to a food, and 20% of school-setting anaphylaxis episodes occur with first-time food exposure 1.