Fig. 4.16 Nocardia lung infection manifesting as multiple lung nodules. Also note ground-glass opacities in right lung

Inflammation (Non-granulomatous)

Many processes can resemble a mass and be appropriately classified (from a finding perspective) into the mass category. The importance is deriving a conclusion based on findings, patterns, and the clinical third dimension.

An example of inflammatory mass would be an abscess. This can appear like the previous case of a cavitary lesion (coccidiomycosis case).

Another example would be infection that manifests as multiple nodules or masses. See Fig. 4.16 for a case of Nocardia lung infection manifesting as multiple lung nodules.

Benign Neoplasm

A benign tumor takes on the shape of a well-defined opacity, whereas a malignant tumor has more spiculated and irregular margins.

Hamartoma

Hamartomas are common benign neoplasms, of which 90% are found in the lung. Hamartomas make up 5% of all solitary lung nodules. They have the following characteristics.

They frequently contain cartilage with fibrous connective tissue and various amounts of fat, smooth muscle, and seromucous glands.

Approximately 30% contain calcium, usually of the “popcorn” variety. They are seen most commonly in the fourth and fifth decades of life.

Fig. 4.17 The malignant mass (left) is spiculated and the benign mass (right) has smooth margins

Fig. 4.18 This AP CXR demonstrates a wellcircumscribed calcified rounded/lobulated nodule near right cardiac border

Case 4.6

Figures 4.18 and 4.19 are examples of a hamartoma.

Findings: Popcorn-like calcification in right lung field near right heart border. CT verifies location in right middle lobe and further characterizes as a popcorn-shaped calcification. A calcified granuloma is incidentally seen in the right upper lung field on the CXR.