E1845. Spectrum of CT Appearance of Lung Cancer and Their Mimickers Such as Infections and Other Processes
  1. Isha Gujrathi; Brigham and Women's Hospital; Dana Farber Cancer Institute
  2. Mark Hammer; Brigham and Women's Hospital
Several benign lung diseases or proliferations may mimic lung carcinoma in its clinical, pathological, and radiological presentation, which makes the differential diagnosis critical. The objective of our exhibit is to describe the spectrum of CT findings and appearances of different subtypes of lung cancer, as well as describe imaging findings in benign lung conditions and infections that may mimic lung cancer.

Educational Goals / Teaching Points
Several benign pulmonary conditions may have imaging findings on CT that may mimic lung cancer. On the other hand, there are instances where a diagnosis of lung cancer is often missed since the imaging findings mimic pulmonary infections or other pathologies. It is important for radiologist to know the CT appearances of various subtypes of lung cancers to be able to accurately diagnose lung cancer and to differentiate from benign pulmonary findings.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
On CT, lung cancer can have varied appearances such as ground-glass or solid nodules, mass-like consolidation, or a cavitary/cystic lesion. A slowly growing ground-glass nodule or development of a solid component in a previously purely ground-glass nodule should raise suspicion for lung cancer. Lung cancers often demonstrate upper lung predominance and are relatively well-defined as compared to infectious conditions. Not all lung cancers demonstrate FDG uptake, particularly slowly growing adenocarcinoma spectrum lesions. On the other hand, some benign pulmonary conditions such as acute infections may demonstrate FDG uptake, and follow-up imaging is key to narrowing the differential diagnosis and ruling out underlying lung cancer. Many cavitating pulmonary infections may resemble lung cancer and vice versa; for example, cavitary tuberculous lesions may mimic squamous cell carcinoma. Sarcoidosis can present as mass-like consolidation with accompanying thoracic lymphadenopathy and can mimic lung cancer.

Lung cancer, particularly adenocarcinoma, can have variable appearance on CT and might be indistinguishable from infection. Adjacent inflammation, if present, is very helpful to exclude lung cancer and make a diagnosis of infection. Ultimately, follow-up examination or tissue diagnosis is crucial in diagnosing early lung cancer.