Differential Diagnosis

• Single most likely diagnosis:
  • Nipple shadow: The small nodular opacity at the right lung base overlying the anterior end of the right sixth rib is most likely a nipple shadow, given its location and description. This is a common finding on chest radiographs and is usually benign.
• Other Likely diagnoses:
  • Non-displaced rib fracture: The minor bony irregularity at the anterior end of the right sixth rib suggests a possible non-displaced fracture. This could be related to trauma or other causes of bone injury.
  • Musculoskeletal injury: Given the location of the bony irregularity and the absence of other significant findings, a musculoskeletal injury such as a strain or contusion could be considered, especially if there is a relevant clinical history.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.):
  • Pulmonary embolism: Although the lung fields are clear, and there's no obvious sign of pulmonary embolism, this condition can sometimes present subtly and must be considered, especially if there are relevant clinical symptoms such as sudden onset of chest pain or shortness of breath.
  • Pneumothorax (small or loculated): Despite the report stating no obvious pneumothorax, a small or loculated pneumothorax could potentially be missed and is critical to identify due to its potential for serious complications.
• Rare diagnoses:
  • Bone tumor: Although rare, a bone tumor could present as a bony irregularity. This would be an unlikely diagnosis without other supporting evidence such as significant pain, a palpable mass, or systemic symptoms.
  • Metastatic disease: Metastatic disease to the rib or lung could present with similar radiographic findings. This would be more likely in the context of a known primary malignancy or systemic symptoms suggestive of metastatic disease.