1/Pulmonary metastases
Pulmonary involvement may occur via three types of spread: hematogenous (the most common),
lymphatic,
and endobronchial.
These routes of the spread to the lungs explain the imaging features.
- Single or multiples nodules :
Nodules are the most common form of metastatic disease (30 to 50 %),
with variable size,
and may range from millimeters to several centimeters.
They may appear ground glass,
solid or mixed solid and ground glass.
Calcification or cavitation may also occur.
Solid nodules :
These nodules are often multiple bilateral,
peripheral,
spherical and sharply demarkated with variable sizes predominating at the periphery of the lungs and the lower lobe Fig. 1 Fig. 2 .
‘‘mass-vessel sign’’ or a feeding vessel may be seen and is characteristic of hematogenous spread.
Hemorrhage around a nodule can create the appearance a ground glass rim especially in hypervascular nodules (renal carcinoma).
Hematogenous metastases can also present as a miliary pattern (profuse,
discrete,
rounded nodules measuring ≤ 3 mm) more likely to be seen in tumors from the thyroid gland,
kidney,
and melanoma.
Cavitated nodules :
Typical cavitary metastases present as an air space lesion with thick irregular walls less frequently with thin walls Fig. 3 Fig. 4.
Chemotherapy may induce cavitation in solid lesions but some primary tumours may metastasize to the lung with cavitated nodules especially squamous cell lesions and adenocarcinoma.
Occurence of a pneumothorax may be the revealing sign of a cavitary metastasis.
Calcified nodules :
Calcification in metastases is uncommon and more likely encountered in matrix-forming primary tumors such as osteosarcoma and chondrosarcoma Fig. 5 Fig. 6.
- Endobronchial metastases:
Endobronchial metastases are rare (2 to 4%) .
It may occur as a result of direct deposition,
via aspiration of tumoral cells,
lymphatic or hematogenous spread,
or direct invasion from tumor in the adjacent parenchyma or lymph nodes.
It appears as soft tissue filling airways Fig. 8 ,
polypoid endobronchial nodule,
bronchial wall thickening and iregularity with atelectasis associated and post obstructive pneumonia.
Fig. 7: Endobronchial metastases from rectal adenocarcinoma. CT shows soft tissue filling the bronchus.
References: Salah Azaiez institute, Tunis/ Tunisia
The extrathoracic malignancies that are most commonly associated with endobronchial metastases are breast,
colorectal carcinoma,
melanoma,
thyroid cancer,
and sarcomas .
- Lymphangitic carcinomatosis:
It is the result of the spread of the tumor in the pulmonary lymphatic system.
It appears as reticular and nodular opacities,
nodular and/or smooth thickening of the interlobular septa and peribronchovascular interstitium with preservation of the secondary pulmonary lobule architecture Fig. 9 Fig. 10 .
It may be focal,
unilateral,
or diffuse and often associated with pleural effusion.
Lymphangitic carcinomatosis is most commonly seen in case of breast,
gastrointestinal,
and genitourinary systems cancers.
The main differential diagnosis is sarcoidosis.
Fig. 11: Lymphangitic carcinomatosis from pancreatic adenocarcinoma.
CT shows diffuse nodular interlobular septal thickening associated with left pleural effusion.
References: Salah Azaiez institute, Tunis/ Tunisia
- Endovascular metastases :
It is the result of tumor emboli with proliferation in the vasculature.
CT shows multifocal dilatation and areas of beading often in mid to small pulmonary arteries.
Infarction leads to the appearence of peripheral airspace.
Tumours most frequently associated with tumor emboli are breast,
prostate and gastric cancer Fig. 12.
2/ Adenopathy
It occurs generally with parenchymal lung metastases most frequently associated with genitourinary system,
head and neck tumours,
breast cancer,
and melanoma.
It can be seen in all nodal groups.
It appears as enlarged lymph node in the mediastinum with or without capsular effraction Fig. 13.
3/ Pleural metastases
Pleural metastases can be the result of hematogenous or lymphatic spread or related to hepatic metastases.
The parietal pleura is less frequently involved than the visceral pleura.
Chest radiographs and CT show an effusion (the most common manifestation) or smooth or nodular thickening of the pleura.
This thickening may be focal or diffuse and suggest malignancy if circumferential > 1 cm with mediastinal pleura involvement.
in this case it becomes indistinguishable from pleural involvement in mesothelioma and lympoma
In extrathoracic malignancy,
it is frequently associated with adenocarcinoma,
pancreas,
stomach and renal cell carcinoma.
Fig. 14: Pleural metastases from ankle synovialosarcoma. Chest X ray and CT show multiple pleural masses massively necrotic involving peripheral and mediastinal pleura and left fissure.
References: Salah Azaiez institute, Tunis/ Tunisia
3/ Cardiac metastases
the pericardium is the most affected by metastatic disease followed by ,
epicardium and then myocardium.
Cardiac metastases are commonly asymptomatic. The typical imaging pattern includes pericardial effusion, multiple nodules or masses,
or diffusely infiltrative lesions.
Cardiac MR is the best tool to detect these locations.
lesions show a low T1 signal (high T1 in melanoma) and high T2 signal .
Enhancement post contrast is generally heterogeneous .CT imaging is also nonspecific,
demonstrating soft tissue masses Fig. 15 Fig. 16 Fig. 17 Fig. 18
Fig. 18
Fig. 19: Metastatic pericardial effusion from breast cancer
CT shows large global pericardial effusion. Note the left breast mass (red arrow).
References: Salah Azaiez institute, Tunis/ Tunisia
Fig. 15: Cardiac metastases from osteosarcoma.
CT scan shows calcified masses involving the right ventricle and the percardium.
References: Salah Azaiez institute, Tunis/ Tunisia
Primary tumors mostly associated with cardiac metastases are adenocarcinoma,
melanoma,leukemia,
lymphoma,
kaposi’s sarcoma.
5/ Parietal metastases
Bone :
Metastatic disease of the bone is the most common type of bone malignancy.
70% of patients with breast and prostate carcinoma develop skeletal metastases.
It may affect all sites,
In fact,
the bone in the chest contains persistant red marrow : vertebrae,
sternum and ribs Fig. 20 Fig. 21
Soft tissue metastasis :
Although soft tissue accounts for about 40% of total body weight,
it is resistant to metastases.
Skin involvement occurs near the site of the primary tumor and breast cancer is the most common primary lesion followed by melanoma.
typical manifestation is cutaneous or subcutaneous nodules
Fig. 22: Cutaneous and subcutaneous metastases in a patient with breast cancer
References: Salah Azaiez institute, Tunis/ Tunisia