What is the likely diagnosis for a 15-year-old male swimmer with right-sided chest pain below the nipple, worsening after sneezing fits and swimming, with no pain on palpation, no shortness of breath, no radiation, and a negative chest X-ray, normal sinus rhythm (NSR) with arrhythmia and ST repolarization on electrocardiogram (EKG), and no family or patient history of cardiac disease?

Right-Sided Chest Pain in an Adolescent Swimmer: Most Likely Diagnosis

This clinical presentation is most consistent with Precordial Catch Syndrome (PCS), a benign musculoskeletal condition that is particularly common in adolescent athletes and swimmers. 1

Why This is Almost Certainly Benign (Not Cardiac)

The clinical features strongly argue against cardiac pathology:

• Right-sided location below the nipple makes ischemic cardiac pain extremely unlikely, as the ACC/AHA guidelines indicate right-sided chest pain has very low probability of ischemia 2
• No pain on palpation helps exclude cardiac causes, as chest wall tenderness markedly reduces ACS probability 2
• Age 15 years with no cardiac history places this patient in an extremely low-risk category, where only 5% of chest pain cases are cardiac in origin 3
• Negative chest X-ray excludes pneumothorax, pneumomediastinum, and other pulmonary emergencies 2
• No shortness of breath, no radiation, pain-free at rest are all features inconsistent with acute coronary syndrome 2

Understanding the ECG Findings

The ECG showing "NSR with arrhythmia, ST repolarization" requires clarification but is likely benign:

• Normal sinus rhythm with respiratory sinus arrhythmia is physiologic in adolescents and athletes 2
• Early repolarization changes are extremely common in young athletes and do not indicate pathology 2
• The ACC/AHA guidelines emphasize that a normal or nondiagnostic ECG occurs in the vast majority of benign chest pain cases 2

Critical point: If the ECG showed true ST-segment elevation, new Q waves, or dynamic ST depression, immediate cardiac evaluation would be mandatory 2, 4. The description provided does not suggest these findings.

Most Likely Diagnosis: Precordial Catch Syndrome

Precordial Catch Syndrome is specifically documented in elite swimmers with the exact presentation described here 1:

• Sharp, localized chest pain triggered by sudden movements (sneezing fits) 1
• Worsens with physical activity (swimming) but resolves at rest 1
• Brief duration (seconds to minutes per episode) over days 1
• No associated cardiac symptoms (dyspnea, syncope, palpitations) 1
• Completely benign and self-limited condition 1

The literature specifically describes two elite swimmers with asthma who experienced acute PCS episodes during competitive swimming that required rescue efforts but proved entirely benign 1.

Alternative Musculoskeletal Diagnoses to Consider

If pain persists beyond 2-3 weeks, consider:

• Costochondritis: Chronic condition in competitive swimmers causing anterior chest wall pain and tenderness at costochondral junctions 5
• Intercostal muscle strain: Common in swimmers from repetitive torso rotation, though typically has pain on palpation 3, 6
• Slipping rib syndrome: Rare but documented in swimmers, presents with persistent lower rib cage pain lasting months 6

Management Algorithm

Immediate management (Day 1-3):

• Reassure patient and family this is benign 1, 3
• Activity modification: avoid forceful sneezing/coughing maneuvers 1
• NSAIDs (ibuprofen 400-600mg TID) if pain interferes with activities 5
• May continue swimming if pain-free at rest 1

If pain persists >2 weeks:

• Re-examine for costochondral tenderness suggesting costochondritis 5
• Consider physical therapy with focus on thoracic mobility 5
• Ensure adequate warm-up before swimming activities 5

Red flags requiring immediate re-evaluation:

• Development of dyspnea, syncope, or palpitations 2, 4
• Pain that interrupts normal activity or occurs at rest 4
• Associated diaphoresis, nausea, or lightheadedness 4

Critical Pitfalls to Avoid

Do not order extensive cardiac workup in this low-risk adolescent with classic benign features, as this leads to unnecessary anxiety, cost, and radiation exposure 2. The ACC/AHA guidelines specifically warn against over-testing in patients with noncardiac chest pain 2.

Do not dismiss as "growing pains" without proper documentation of benign features and clear return precautions 3. Parents need specific instructions about warning signs.

Do not restrict all athletic activity unnecessarily, as PCS is self-limited and activity modification (not cessation) is appropriate 1, 3.

When to Refer to Cardiology

Cardiology referral would only be indicated if 2:

• Pain becomes exertional and reproducible with exercise
• Development of syncope or pre-syncope during activity
• Family history emerges of sudden cardiac death <50 years
• ECG shows true pathologic changes (not early repolarization)

In this case, with the clinical presentation described, no cardiology referral is needed 1, 3.