Solitary Pulmonary Nodule

What are the criteria for calling a lesion as solitary pulmonary nodule?

Single lesion
Round or oval
Between 1-5 cms in diameter
- Lesions less than 1 cm are called nodules
- Lesions larger than 5 cms are called masses

Common causes for solitary pulmonary nodule

Lung Cancer / Adenocarcinoma
Benign tumors
Granuloma

How do patients with solitary pulmonary nodule present?

In the majority incidentally
If malignant, they may present with symptoms related to metastasis

A case of adenocarcinoma presenting as solitary pulmonary nodule:

Adenocarcinoma Lung

Note the solitary pulmonary nodule.
The film on the right is an old x-ray. The lesion was not present one year ago.

A case of granuloma presenting as solitray pulmonary nodule:

CXR

Arrow points to the solitary pulmonary nodule.
White arrowhead points to the right hilum which is full and dense.
Black arrowheads point to calcification, evident in both hilum.

CT of the same patient above

A. Calcified hilar node
B. Calcification of the solitary pulmonary nodule

What are the imaging findings that indicate that a given solitary pulmonary nodule is benign?

Stable in size for two years
Demonstrable calcium

are two strong points in favor of a benign lesion.