Pericarditis: The Most Likely Diagnosis
This clinical presentation—flank and lateral chest wall pain that improves with sitting up and worsens with bending over—is classic for acute pericarditis, which characteristically presents with sharp, pleuritic chest pain that is relieved by sitting up or leaning forward. 1
Key Diagnostic Features
Classic Presentation Pattern
- Positional pain relief is pathognomonic: Pericarditis pain classically improves with sitting up or leaning forward, exactly as described in this case 1
- The pain is typically sharp and pleuritic in nature, though these findings may not always be present 1
- Pain can radiate to the lateral chest wall and flank regions, reflecting the anatomic distribution of pericardial inflammation 1
Important Caveat
While this presentation strongly suggests pericarditis, the American Heart Association emphasizes that classic positional features are not always present in all cases of pericarditis 1. However, when they are present—as in this scenario—they are highly suggestive of the diagnosis.
Immediate Diagnostic Workup
Essential First Steps
- Obtain a 12-lead ECG immediately: Look for widespread ST-elevation with PR depression, which is the electrocardiographic hallmark of pericarditis, though changes may be nonspecific and transient 1
- Auscultate carefully for a pericardial friction rub, which may be audible but is often absent 1
- Check troponin levels: A minimally elevated troponin does not appear to confer worse prognosis in pericarditis patients and likely indicates myopericarditis 1
Advanced Imaging When Indicated
- Transthoracic echocardiography (TTE) is effective to determine the presence of pericardial effusion, ventricular wall motion abnormalities, valvular abnormalities, or restrictive physiology 1
- Cardiac MRI with gadolinium is useful if diagnostic uncertainty exists or to determine the presence and extent of myocardial and pericardial inflammation and fibrosis 1
- Cardiac CT may be reasonable to assess pericardial thickening, though evidence is limited 1
Treatment Algorithm
First-Line Pharmacological Management
- Initiate a 1-2 week course of NSAIDs for the pleuritic-type inflammatory pain 2
- Add low-dose colchicine if symptoms persist despite NSAID therapy 2
- Consider acetaminophen as an alternative if NSAIDs are contraindicated 2
Adjunctive Measures
- Apply ice packs or heat as non-pharmacological pain relief 2
- Topical analgesics like lidocaine patches may provide localized relief with minimal systemic effects 2
Critical Differential Diagnoses to Exclude
Life-Threatening Alternatives
- Pulmonary embolism: Dyspnea followed by pleuritic chest pain is the most common presentation, with risk factors including recent surgery, trauma, immobilization, malignancy, smoking, obesity, and oral contraception 1
- Acute coronary syndrome: Must be excluded, particularly in patients over 35 years or with cardiac risk factors 3
- Aortic dissection: Can present with severe acute chest pain radiating to the back in the setting of acute severe aortic insufficiency 1
Other Musculoskeletal Causes
While less likely given the classic positional features, consider:
- Costochondritis: Accounts for 42% of nontraumatic musculoskeletal chest wall pain, diagnosed by tenderness to palpation of costochondral joints 1, 2
- Rib fractures: Particularly post-tussive fractures, though these typically have a clear trauma history 1
- Slipping rib syndrome: Pain in the lower chest and upper abdomen that worsens with bending, though this typically affects ribs 8-10 4
Common Pitfalls to Avoid
- Do not assume musculoskeletal origin without ECG in patients over 35 years or with cardiac risk factors 3
- Do not dismiss the diagnosis if troponin is mildly elevated: This suggests myopericarditis but does not worsen prognosis 1
- Do not expect all classic features to be present: ECG changes may be transient and friction rubs are often absent 1
- Recognize that most cases in developed nations are viral, though tuberculosis should be considered in appropriate clinical contexts 1