What are the causes of round spots in the lungs, also known as pulmonary (lung) nodules?

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Last updated: April 7, 2025 • View editorial policy

Differential Diagnosis for Round Spots in the Lung

Single Most Likely Diagnosis

  • Pulmonary metastases: This is often the first consideration for round spots in the lung, especially if there's a known history of cancer. Metastases can appear as multiple, rounded nodules scattered throughout the lung fields.

Other Likely Diagnoses

  • Pulmonary nodules: These can be benign or malignant and may appear as round spots on imaging. They can be due to a variety of causes including granulomas, hamartomas, or primary lung tumors.
  • Infectious nodules: Certain infections, such as tuberculosis or fungal infections, can cause round spots in the lung due to the formation of granulomas or abscesses.
  • Pulmonary infarcts: These can appear as round, wedge-shaped, or irregular areas of consolidation and are due to pulmonary embolism.

Do Not Miss Diagnoses

  • Pulmonary embolism with infarction: While not always presenting as round spots, it's crucial to consider this diagnosis due to its high mortality rate if untreated.
  • Tuberculosis: Especially in endemic areas or in immunocompromised patients, TB can present with round spots due to granulomas and is critical to diagnose due to its public health implications and the need for specific treatment.
  • Fungal infections: In immunocompromised patients, fungal infections like histoplasmosis or cryptococcosis can present with round lung spots and are potentially life-threatening if not treated promptly.

Rare Diagnoses

  • Pulmonary arteriovenous malformations (AVMs): These can appear as round spots due to the abnormal connection between arteries and veins in the lung.
  • Pulmonary hamartomas: Benign lung tumors that can appear as round, well-defined nodules on imaging.
  • Rheumatoid nodules: In patients with rheumatoid arthritis, these can appear as round spots in the lung due to the formation of rheumatoid nodules.
  • Lymphoma: Both Hodgkin and non-Hodgkin lymphoma can involve the lung and present with round spots or nodules, though this is less common.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.