Grand Rounds- Cannon Ball Secondaries And Pulmonary Metastasis.

Pulmonary Medicine Blog By Dr Deepu.
Lung Cancer incidence is on rise so does the metastasis to the lungs. As the age increases the incidence of lung cancer and also the lung metastasis increases.
An elderly male presented to us with weakness and giddiness associated with chest pain since a month. Clinical examination revealed an enlarged right supraclavicular node. Rest of the clinical findings were normal.

Before proceeding study this chest X Ray carefully.

Chest X ray shows large , well circumscribed, round pulmonary nodules that are distributed in upper mid and lower lung zones bilaterally, some forming into a mass but most of them are seen concentrated in the lower zones and mostly along the peripheral lung fields. also there is a homogenous mass in the left mid zone just lateral to the descending aorta. The diagnosis could be cannon ball secondaries with unknown primary.
Study the CT images before proceeding

The CT scan above shows multiple nodules of varying sizes, concentrated mostly in the lower lobes and left upper lobe bronchus seems occluded partially by the mass. Here study this mediastinal window and coronal cuts

The mediastinal window shows a few lymph nodes in paratracheal and subcarinal area.
We screened his brain , GIT, bones and Genitourinary system for primary Tumor, the scans were normal , further we considered bronchoscopy and Scopy showed a fungating mass in the left upper lobe, Biopsy reports are awaited. Will update once it becomes available.
Cannonball metastases are large, well circumscribed, round pulmonary metastases that appear, well, like cannonballs. 
The French term "envolĂ©e de ballons" which translates to "balloons release" is also used to describe this same appearance. 

Causes of Cannon Ball Metastais
Classical- renal cell carcinoma  choriocarcinoma,
Less commonly - prostate cancer, synovial sarcoma or endometrial carcinoma.
Pulmonary metastases are very common and it is  due to metastatic spread to the lungs from a variety of tumour. It can spread via blood or lymphatics. 
Clinical presentation
Pulmonary metastases are asymptomatic usually,
The constitutional symptoms are related to primary cancerous metastatic condition
Those attributable to the primary tumour dominating. 
Haemoptysis , Chest pain , difficulty in breathing and pneumothorax are sometimes the presenting symptom.
Tumour cells reach the lungs via the pulmonary circulation, where they lodge in small distal vessels. 
The most common primaries to result in pulmonary metastases include: 
breast carcinoma
colorectal carcinoma
renal cell carcinoma
uterine leiomyosarcoma
head and neck squamous cell carcinoma
Primaries which most frequently metastasise to lungs (although in themselves much less common tumours) include:
Ewing sarcoma
malignant melanoma
testicular tumours
thyroid carcinoma
Radiographic features
Pulmonary metastases characteristically appear as peripheral, rounded nodules of variable size, scattered throughout both lungs . uncommon features include consolidation, cavitation, calcification, haemorrhage and secondary pneumothorax.

Plain radiograph
Plain films are insensitive, although frequently able to make the diagnosis, as often pulmonary metastases are large and numerous.
CT is excellent at visualising pulmonary nodules. Typically metastases appear of soft tissue attenuation, well circumscribed rounded lesions, more often in the periphery of the lung. They are usually of variable size, a feature which is of some use in distinguishing them from a granuloma.
A prominent pulmonary vessel has frequently been noted heading into a metastasis. This is termed the feeding vessel sign.
Some tumours have a predilection for innumerable small metastases (miliary pattern):
Malignant melanoma
Renal cell carcinoma
Thyroid carcinoma
Trophoblastic disease( choriocarcinoma)
Pulmonary metastasis may be single. Seen most frequently  in colorectal carcinoma.
Other primaries which often present with solitary metastases include:
Malignant melanoma
skeletal sarcoma
adenocarcinomas in general
Adenocarcinoma metastases may rather than displace or destroy adjacent lung parenchyma, cells grow in a lepidic fashion (spread along aleveolar walls) resulting in pneumonia-like consolidation. Air bronchograms may also be visible.
Cavitation is present in ~4% of cases. The most common primary is squamous cell carcinoma, most often from the head and neck or from the lung. Other primaries include adenocarcinomas, and sarcomas.
Calcification, although uncommon and more frequently a feature of benign aetiology (e.g. granuloma or hamartoma) is also seen with metastases, particularly those from papillary thyroid carcinoma and adenocarcinomas. Treated metastases, osteosarcomas and chondrosarcomas may also contain calcific densities.
halo of ground-glass opacity representing haemorrhage can be seen, particularly surrounding haemorrhagic pulmonary metastases, such as choriocarcinoma and angiosarcoma.
Treatment and prognosis
In general presence of pulmonary metastases is an ominous finding, indicating poor prognosis. The specific prognosis will however depend on the primary tumour.

Tumours with prominent necrosis located near a pleural surface may result in a pneumothorax. Osteosarcoma is classically described as the pulmonary metastasis that results in pneumothorax. Another cause of pneumothoraces include cystic or cavitatory pulmonary metastases.

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