What is the significance of the size in the diagnosis of solitary pulmonary nodules?

Updated: Aug 22, 2019
  • Author: Pujan H Patel, MD; Chief Editor: Guy W Soo Hoo, MD, MPH  more...
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Although a well-defined nodule of smaller size that is clearly visible on chest radiographs may be calcified and benign, small lesions may very well be early stage bronchogenic carcinoma. A lesion greater than 4 cm in diameter is very likely a bronchogenic carcinoma, although exceptions include lung abscess, Wegener's granulomatosis, lymphoma, round pneumonia, rounded atelectasis, and hydatid cyst.

Midthun et al reported that the likelihood of malignancy was 50% for nodules greater than 20 mm and 18% for those 8-20 mm in diameter. With lesions smaller than 8 mm, a sharp decline is noted, with nodules of 4-7 mm having a likelihood of malignancy of only 0.9% and those less that 3 mm, only 0.2%. [20]

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