FM Radiology Case - Cavitary Disease

Question 1

Define a cavity in the lung.

Answer 1

Air-containing space surrounded by a wall

Question 2

What are the elements of a systematic evaluation for cavitary lung disease?

Answer 2

1. Number
2. Location
3. Wall thickness
4. Lining of the wall
5. Contents
6. Other associated findings

Question 3

What are the two general etiologies leading to multiple cavities?

Answer 3

Hematogeous etiology and bronchogenous etiology

Question 4

DDx - hematogenous etiology of multiple cavities on lung x-ray?

Answer 4

Metastases, septic emboli, vasculitis

Question 5

DDx - bronchogenous etiology of multiple cavities on lung x-ray?

Answer 5

Aspiration abscess, TB, coccidiomycosis, bronchiectasis

Question 6

DDx - single cavities on lung x-ray?

Answer 6

Primary lung cancer, post-traumatic lung cyst, many other diseases

Question 7

Aspiration lung abscesses are in dependent locations based on the position when the patient aspirated. 85% of aspiration lung abscesses are located in what locations?

Answer 7

Superior segment of lower lobes, axillary sub-segment of anterior and posterior segments of RUL

Question 8

When can aspiration lung abscesses be ruled out?

Answer 8

When the cavity is located in the apical segment of upper lobes

Question 9

Where does TB classically occur?

Answer 9

Apical segments of lower and upper lobes

Question 10

DDx - thick-walled (>5mm cavities)

Answer 10

Aspiration lung abscess, necrotizing pneumonia, squamous cell cancer, blastomycosis, Wegener’s granulomatosis

Question 11

DDx - thin-walled (<1mm cavities)

Answer 11

M. kansasii, coccidiomycosis, open negative TB, blebs, congenital cysts, metastatic cavitating squamous cell carcinoma from larynx or cervix

Question 12

DDx - irregular, nodular, shaggy lining of the wall

Answer 12

Lung abscess, necrotizing pneumonia, cavitating primary cancer

Question 13

DDx - contents - air fluid level

Answer 13

Lung abscess, cavitating primary lung cancer, active bleeding in the cavity

Question 14

DDx - contents - fungal ball

Answer 14

Aspergillosis

Question 15

Associated features seen with lung cancer?

Answer 15

Ipsilateral lymph nodes, lytic bone lesion

Question 16

Associated feature seen with fungal ball?

Answer 16

Adjacent thickening of the pleura

Question 17

Lesions that evolve?

Answer 17

Infected bullae, aspergilloma, subacute necrotizing asgerillosis, bleeding from Rasmussen’s aneurysm in a tuberculous cavity

Question 18

Why does aspiration lung abscess occur in the superior segment of lower lobes?

Answer 18

Gravity dependent phenomenon; location of aspiration depends on the position of patient at the time of aspiration. If the patient is supine on their back, the first dependent entry is into the superior segment of lower lobe. If the patient is in right lateral decubitus position, it is the axillary sub-segments of RUL. If you are in supine position with face down, aspiration into lungs does not occur. Hence it is very unusual to encounter aspiration lung abscesses in anterior segments.

Question 19

What is the process for determining the etiology of a cavity?

Answer 19

1. Single or multiple?

If single: location, wall thickness, associated findings

If multiple: vascular or bronchial?

Vascular - sharp contrast with the rest of the lungs

Bronchial - when there is fuzziness around the cavity