Inflammation and Immune Pathology USMLE Step 1 Practice Question
A 28-year-old woman with documented penicillin allergy develops sudden-onset dyspnea, chest pain, and urticaria 2 hours after receiving penicillin for streptococcal pharyngitis. Vital signs show BP 88/52 mmHg, HR 118/min, RR 24/min, SpO2 91% on room air. Physical examination reveals angioedema and diffuse wheezing. Serum tryptase is elevated at 8.5 ng/mL. IgE-mediated mast cell degranulation is suspected. Which hypersensitivity reaction type best explains this clinical presentation?
Answer choices
- AType I hypersensitivity with IgE-mediated mast cell degranulationCorrect answer
- BType II cytotoxic reaction with complement activation
- CType III immune complex deposition in tissues
- DDirect mast cell activation independent of IgE
- EType IV delayed-type hypersensitivity response
- FType I hypersensitivity with IgG-mediated complement activation
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