Blood & Lymphoreticular/Immune, Physiology, USMLE Step 1 - Full Vignette with Extended Explanations скачать в хорошем качестве

Blood & Lymphoreticular/Immune, Physiology, USMLE Step 1 - Full Vignette with Extended Explanations

A 20-year-old man develops watery, itchy eyes and sneezing within minutes of entering a cat owner s apartment, with clear nasal discharge and symptoms that subside after he leaves. He has a history of similar symptoms when exposed to pets and dust since childhood, and examination reveals pale, boggy nasal mucosa and eosinophilia. What clinical and immunologic clues should you use to identify the underlying process responsible for his recurrent symptoms? VIDEO INFO Category: Blood & Lymphoreticular/Immune, Physiology, USMLE Step 1 Difficulty: Easy - Basic level - Suitable for medical students Question Type: Diagnosis - Identify conditions based on clinical presentation Case Type: Tricky Findings Explore more ways to learn on this and other topics by going to https://endlessmedical.academy/auth?h... QUESTION A 20-year-old man presents in late spring because his eyes water and itch and he sneezes when he visits his girlfriend s apartment, where a cat lives. Within minutes of entering the room where the cat stays, he develops clear nasal discharge, nasal itching, and repetitive sneezing; symptoms fade a few hours after leaving. He denies fever, myalgias, or purulent discharge.... OPTIONS A. IgE-mediated immediate (type I) hypersensitivity causing allergic rhinitis triggered by cat dander exposure, with pale boggy turbinates and eosinophilia B. Nonallergic (vasomotor) rhinitis from irritants without IgE involvement despite negative allergen testing and normal nasal mucosa C. Viral upper respiratory infection presenting with fever, myalgias, erythematous nasal mucosa, and purulent nasal discharge for several days D. Acute bacterial sinusitis with facial pain, persistent purulent nasal drainage, and sustained fever exceeding 3 days CORRECT ANSWER A. IgE-mediated immediate (type I) hypersensitivity causing allergic rhinitis triggered by cat dander exposure, with pale boggy turbinates and eosinophilia EXPLANATION "IgE-mediated immediate (type I) hypersensitivity causing allergic rhinitis triggered by cat dander exposure, with pale boggy turbinates and eosinophilia" best fits this vignette because symptoms begin within minutes of exposure to a known aeroallergen (cat), improve after leaving the environment, and respond promptly to an oral second-generation antihistamine. Positive skin-prick and serum specific IgE to cat and dust mite confirm IgE-mediated sensitization. The exam shows classic pale, boggy nasal turbinates with clear rhinorrhea and watery, injected conjunctivae; mild peripheral eosinophilia further supports allergic inflammation. These are textbook features of type I (immediate) hypersensitivity: allergen cross-links IgE bound to mast cells/basophils - rapid mediator release (histamine, leukotrienes) - sneezing, itching, rhinorrhea, and ocular symptoms; a late-phase eosinophilic component can prolong congestion. Per the 2020 AAAAI/ACAAI rhinitis practice parameter, confirmatory testing with specific IgE and the clinical pattern of rapid onset after exposure establish the diagnosis, and response to antihistamine is expected. Nonallergic (vasomotor) rhinitis would show negative allergen testing, normal-appearing (often erythematous) mucosa, and triggers such as strong odors, temperature changes, or irritants; it typically lacks the immediate, exposure-linked pattern and conjunctival itching, and antihistamines are less effective.... Further reading: Links to sources are provided for optional further reading only. The questions and explanations are independently authored and do not reproduce or adapt any specific third-party text or content. --------------------------------------------------- Our cases and questions come from the https://EndlessMedical.Academy quiz engine - multi-model platform. Each question and explanation is forged by consensus between multiple top AI models (i.e. Open AI GPT, Claude, Grok, etc.), with automated web searches for the latest research and verified references. Calculations (e.g. eGFR, dosages) are checked via code execution to eliminate errors, and all references are reviewed by several AIs to minimize hallucinations. Important note: This material is entirely AI-generated and has not been verified by human experts; despite stringent consensus checks, perfect accuracy cannot be guaranteed. Exercise caution - always corroborate the content with trusted references or qualified professionals, and never apply information from this content to patient care or clinical decisions without independent verification. Clinicians already rely on AI and online tools - myself included - so treat this content as an additional focused aid, not a replacement for proper medical education. Visit https://endlessmedical.academy for more AI-supported resources and cases. This material can not be treated as medical advice. May contain errors. ---------------------------------------------------