Physical assessment: In a 35‑year‑old male with chronic cough who now has two episodes of hemoptysis, four days of fever, and productive yellow sputum, provide three key differential diagnoses with rule‑in and rule‑out criteria for each in chart format.

Three Key Differential Diagnoses for 35-Year-Old Male with Chronic Cough, Hemoptysis, Fever, and Productive Sputum

The most critical immediate concern is community-acquired pneumonia, which must be ruled out first given the acute fever, productive yellow sputum, and hemoptysis—this requires urgent assessment of vital signs and chest radiography. 1, 2

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Differential Diagnosis Chart

Diagnosis	Rule-In Criteria	Rule-Out Criteria
Community-Acquired Pneumonia	• Heart rate >100 beats/min [1,2] • Respiratory rate >24 breaths/min [1,2] • Temperature >38°C [1,2] • Focal consolidation, egophony, or fremitus on chest exam [1,2] • Asymmetrical lung sounds [2] • Productive yellow/purulent sputum [1] • Hemoptysis [2] • Chest X-ray showing infiltrate	• All four vital sign/exam findings absent (heart rate <100, respiratory rate <24, temperature <38°C, no focal consolidation/egophony/fremitus) [1] • Normal chest radiograph [2] • Symptoms resolve spontaneously within days without antibiotics [1]
Bronchiectasis	• Chronic productive cough with large sputum volume (>30 mL/day) [1] • Recurrent hemoptysis (due to bronchial arterial proliferation) [1] • History of previous pneumonia or recurrent infections [1] • Crackles and rhonchi on exam (though may be absent) [1] • High-resolution CT showing abnormal airway dilation [1] • Sputum culture positive for H. influenzae, S. aureus, S. pneumoniae, or Pseudomonas [1]	• Sputum production <30 mL/day [1] • Normal high-resolution CT scan (bronchiectasis requires radiographic confirmation of airway dilation) [1] • Single acute episode without chronic history [1] • Physical exam and crackles do not correlate with presence/absence of bronchiectasis [1]
Tuberculosis	• Cough >3 weeks duration [2] • Fever (especially if prolonged/intermittent) [2] • Hemoptysis [2] • From high TB prevalence area or exposure history [2] • Systemic symptoms: weight loss, night sweats [2] • Chest X-ray showing upper lobe infiltrates, cavitation, or lymphadenopathy [2] • Positive sputum smear for acid-fast bacilli [2] • Positive sputum culture for Mycobacterium tuberculosis [2]	• Negative sputum smears (3 samples) for acid-fast bacilli [2] • Negative TB culture [2] • Normal chest radiograph [2] • No TB risk factors or exposure [2] • Rapid symptom resolution with standard antibiotics [1]

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Clinical Reasoning Algorithm

Step 1: Immediate Vital Sign Assessment

• Check vital signs immediately to determine if pneumonia is present: heart rate, respiratory rate, temperature 1, 2
• Perform focused lung examination for asymmetrical sounds, focal consolidation, rales, egophony, fremitus 1, 2
• If ANY vital sign abnormality present OR abnormal lung findings: obtain chest radiograph urgently 1, 2

Step 2: Risk Stratification for Tuberculosis

• Assess TB risk factors: geographic origin, exposure history, duration of symptoms, systemic symptoms 2
• If cough >3 weeks + fever + hemoptysis + any TB risk: obtain chest X-ray and collect three sputum samples for acid-fast bacilli smears and culture 2
• TB must be considered even in low-prevalence areas when common causes are ruled out 2

Step 3: Evaluate for Chronic Underlying Lung Disease

• Given chronic cough history: consider bronchiectasis, especially if recurrent infections or large sputum volumes 1
• Hemoptysis in bronchiectasis results from bronchial arterial proliferation and arteriovenous malformations 1
• High-resolution CT is required to diagnose bronchiectasis (demonstrates abnormal airway dilation) 1

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Critical Pitfalls to Avoid

• Do not assume purulent sputum alone distinguishes pneumonia from acute bronchitis—vital signs and chest exam findings are essential 1
• Do not rely on physical exam findings alone for bronchiectasis—crackles may be absent, and their presence does not correlate with CT findings 1
• Do not dismiss TB based solely on low local prevalence—maintain high suspicion with prolonged cough, fever, and hemoptysis 2
• Hemoptysis is a red flag requiring immediate chest radiography regardless of other findings 2
• The character and timing of cough have no diagnostic value and should not be used to rule diagnoses in or out 3, 4

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Next Steps After Initial Assessment

• If pneumonia confirmed: initiate appropriate antibiotic therapy based on severity and risk factors 1
• If TB suspected: isolate patient, initiate airborne precautions, and notify public health authorities while awaiting culture results 2
• If bronchiectasis suspected: obtain high-resolution CT chest and consider referral to pulmonology for further evaluation and management 1
• If all three ruled out: expand differential to include pertussis (if paroxysmal cough), postinfectious cough, or uncommon causes requiring CT and possible bronchoscopy 1, 3, 2