Differential Diagnosis for 30-year-old Male Veteran with Right Sided Lower Rib Pain

Single Most Likely Diagnosis

• Musculoskeletal strain or costochondritis: The patient's sharp pain that worsens with deep breaths and is localized to the lower ribs suggests a musculoskeletal issue, possibly related to strain or inflammation of the costochondral junctions. The absence of systemic symptoms or specific aggravating factors supports this diagnosis.

Other Likely Diagnoses

• Pulmonary embolism (less likely due to lack of systemic symptoms): Although the patient denies shortness of breath, the acute onset of sharp pain that worsens with deep breaths could suggest a pulmonary embolism. However, the lack of other symptoms such as chest pain, shortness of breath, or systemic symptoms like fevers makes this less likely.
• Gastrointestinal issue (e.g., constipation-related pain): The patient's report of constipation and small pellet-like bowel movements could contribute to abdominal or referred pain, but the pain's location and characteristics (sharp, worse with deep breaths) make this less likely as a primary cause.
• Intercostal muscle strain: Similar to musculoskeletal strain, intercostal muscle strain could cause sharp pain that worsens with deep breathing or movement.

Do Not Miss Diagnoses

• Pneumothorax: Although the patient denies shortness of breath, a pneumothorax could present with sharp chest pain that worsens with deep breathing. This is a critical diagnosis to consider due to its potential for serious complications.
• Myocardial infarction: While less common in a 30-year-old, myocardial infarction can present atypically, especially in individuals with risk factors. The sharp pain and its relation to breathing could be atypical presentations of cardiac ischemia.
• Pulmonary embolism (reiterated for emphasis): Given its potential severity, pulmonary embolism must be considered, even with the patient's lack of typical symptoms.

Rare Diagnoses

• Rib fracture: An acute fracture could cause sharp pain, but there's no reported trauma or strenuous activity that would typically precede such an injury.
• Tumor (e.g., metastatic disease to the ribs): While extremely rare in a 30-year-old without a known primary cancer, any new onset of unexplained pain warrants consideration of neoplastic processes, especially in a veteran population where exposure histories might increase certain risks.
• Herpes zoster (shingles): Could present with sharp, unilateral pain, but typically would be accompanied by a rash, which the patient does not mention.