Differential Diagnosis for a Speculated Mass on the Lung in CT Scan

• Single most likely diagnosis
  • Lung cancer: This is the most common cause of a speculated mass on the lung, especially in smokers or those with a history of smoking. The speculated appearance is often due to the tumor's invasive growth pattern into surrounding lung tissue.
• Other Likely diagnoses
  • Pulmonary metastasis: Metastases from other primary cancers can also present as speculated masses on the lung, especially if the primary cancer has a high propensity for lung metastasis, such as breast, colon, or renal cell carcinoma.
  • Tuberculosis (TB): Although less common in some regions, TB can cause speculated masses, particularly in endemic areas or in immunocompromised patients. The speculated appearance may be due to the healing process of TB lesions.
  • Fungal infections: Certain fungal infections like aspergillosis or histoplasmosis can cause lung masses with speculated borders, especially in immunocompromised individuals.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Pulmonary embolism (PE): Although PE typically presents with different symptoms and imaging findings, a large PE can occasionally mimic a lung mass. Missing this diagnosis can be fatal.
  • Pneumonia: Certain types of pneumonia, especially those caused by atypical organisms or in immunocompromised hosts, can present with mass-like lesions. Delayed diagnosis can lead to severe consequences.
• Rare diagnoses
  • Hamartoma: A benign lung tumor that can have a speculated appearance on CT scan due to its mixture of cartilaginous, fat, and soft tissue components.
  • Pulmonary arteriovenous malformation (AVM): A rare congenital anomaly that can present as a speculated mass due to the abnormal vascular structure.
  • Inflammatory pseudotumor: A rare, benign lesion that can mimic a lung mass and have a speculated appearance due to its inflammatory and fibrotic components.