Differential Diagnosis for Persistent Chest Pain after Trauma with a 4 mm Peripheral Lung Nodule

• Single most likely diagnosis:
  • Benign lung nodule: Given the small size (4 mm) and peripheral location of the nodule, a benign etiology such as a granuloma or a small hamartoma is the most likely diagnosis. The lack of associated symptoms or findings suggestive of malignancy (e.g., significant weight loss, night sweats, or lymphadenopathy) and the absence of a clear history of exposure to carcinogens also support this likelihood.
• Other Likely diagnoses:
  • Traumatic contusion: Although the report does not mention any discernible rib fractures or significant pulmonary findings, a small traumatic contusion could present as a peripheral nodule, especially in the context of recent trauma.
  • Pulmonary infarct: If the patient had a pulmonary embolism (not directly evident from the provided findings but possible in the context of trauma), it could result in a peripheral nodule representing an infarct.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed):
  • Malignant lung nodule: Although less likely given the small size, any new or growing nodule, especially in a smoker or someone with a significant family history of cancer, necessitates consideration of malignancy. Early detection of lung cancer can significantly improve prognosis.
  • Pulmonary embolism (PE): While the findings do not directly suggest a PE, the history of trauma increases the risk. A PE can be life-threatening and requires immediate attention.
  • Aortic injury: The report mentions a normal caliber to the thoracic aorta, but given the history of trauma, an aortic injury (e.g., dissection or transection) must be considered, as it is a potentially fatal condition.
• Rare diagnoses:
  • Infectious nodules (e.g., coccidioidomycosis, histoplasmosis): In endemic areas, fungal infections can cause lung nodules. The history of trauma might not be directly related, but in an immunocompromised patient or someone with specific exposures, these should be considered.
  • Vascular malformations or aneurysms: Rarely, a peripheral nodule could represent a vascular anomaly, such as an arteriovenous malformation or a small aneurysm, especially if the patient has a relevant medical history or genetic predisposition.