Cardiothoracic & Vascular (Part 1)

The size of the tumour and visceral pleural invasion make this lesion T2a. Chest wall invasion would make this tumour T3 however this is not reported as present. Enlarged ipsilateral hilar, mediastinal and subcarinal nodes are N2. There is no evidence of a M1a/M1b lesion.

There are new guidelines from the British Thoracic Society for the investigation and management of pulmonary nodules (2015). They have produced a lengthy document, but the first few pages provide a summary of the recommendations, with flow-charts to help guide management. The guidelines overall aim to help reduce imaging follow-up. There is also a focus on using volumetric analysis of nodules, and calculating the risk of a nodule being malignant using a risk calculator (link provided in the references). They want to standardise the diagnostic approach for nodules detected incidentally and those that are found during screening.

Nodules with a maximum diameter of <5mm do not get followed up (instead of 4mm with the old Fleischner Guidelines). Nodules with a maximum diameter between 5 - 6mm get a CT at 1 year. Those between 6 - 8mm get a CT at 3 months. When these follow-up CTs are performed, ideally volumetrics should be calculated, and further follow-up guided by the volume doubling time (VDT). Those with a maximum diameter of >8mm get their risk calculated using the Brock Model Risk calculator (provided on the BTS website). The flow charts then determine follow-up based on the risk of malignancy calculated. If it has a malignant risk of <10%, then a CT in 3 months is advised. If it has a risk >10%, then a PET may be appropriate.

This particular nodule has a maximum diameter of 7mm. Therefore guidance states w should repeat CT at 3 months and calculate a VDT. Under old guidance (Fleischner society guidelines) the average size of this nodule would be calculated (6mm in this case), which for a low risk patient would mean a 12 month follow up CT.ReferencesBritish Thoracic Society Guidelines
https://www.brit-thoracic.org.uk/document-library/clinical-information/p...

British Thoracic Society Risk Calculator
https://www.brit-thoracic.org.uk/guidelines-and-quality-standards/pulmon...

Thymolipomata are usually incidentally discovered on imaging of the chest for other reasons. They may however present with dyspnoea, chest pain or cough. Imaging characteristics are as described, they may also have some heterogeneity due to thymic soft tissue within the mass. Liposarcoma are generally of higher attenuation and less homogenous, as are teratomas. Mediastinal lipomatosis more often occurs in the upper mediastinum. Oesophageal lipomas tend to arise within the lumen of the oesophagus and cause dysphagia.

The differential diagnosis above is of an anterior mediastinal mass. Mature teratomas are a type of germ cell tumour which are usually cystic and frequently contain fat and calcification. They are usually discovered incidentally and displace rather than invade surrounding structures. They may become symptomatic when large. Immature teratomas are usually solid. Thymomas may contain fat (thymolipoma) however calcification is not a usual feature in these tumours.

Extramedullary haematopoesis is a response to inadequate haemoglobin production and is seen in patients with haemolytic anaemias and myelofibrosis. Appearances on CT are of heterogenous soft tissue masses in the paravertebral regions with inhomogeneous contrast enhancement. The imaging appearances together with the clinical context are highly suggestive of extramedullary haematopoesis in this case. The other options are less likely in this case and have different imaging appearances, outlined in the short articles below.

Alpha-1 antitrypsin deficiency is a hereditary metabolic disorder that typically affects middle aged adults and manifests as basal panlobular emphysema and hepatic cirrhosis.
Sarcoidosis can affect both the lung and liver however the imaging findings outlined above are atypical (hepatosplenomegaly, upper/mid zone lung disease).
Schistosomiasis can also affect the lung and the liver, typically with small pulmonary nodules and ground glass in the lung and liver cirrhosis.
Haemochromatosis causes liver cirrhosis but does not typically affect the lungs.
Cystic fibrosis can also affect both the liver and the lungs however the patient was previously well, which would not be the case if the patient had a history of CF.

The history of stroke and subsequent immobility (supine in bed) raise suspicion of aspiration pneumonia and pulmonary embolism. The patient is anticoagulated making PE less likely and the CXR appearances are against this also. Aspiration pneumonia in recumbent patients commonly affects the posterior segments of the upper lobe and superior segments of the lower lobes.

Lymphangiomyomatosis (LAM) is a multisystem disorder which almost exclusively affect females of child bearing age. It may occur in isolation or in association with tuberous sclerosis. Chest findings include chylous pleural effusion, hyperinflation, variable sized thin walled cysts and recurrent pneumothoraces.

A mass extending above the superior clavicle with lung tissue located between the mass and the neck is likely to lie in the posterior mediastinum. This appearance is termed the cervicothoracic sign and is suggestive of a posterior mediastinal mass. Obliterated left subclavian artery reflection, Effacement/dense ascending aorta, & Obliterated cardiophrenic angle are suggestive of an anterior mediastinal mass. Pseudoparavertebral line (left) is suggestive of a middle mediastinal mass.

A - D are all signs of abnormal vessels which may point to the source of bleeding. A filling defect within a vessel is more likely to represent an embolus or vessel thrombosis which is not relevant in this case.

Pericardial cysts are usually discovered incidentally during examinations performed for other reasons. Their imaging appearances are as described. The other lesions listed would have different attenuation and/or enhancement characteristics.

Ankylosing spondylitis is a multisystem autoimmiune condition which usually presents in young men. The condition manifests with respiratory (upper zone fibrosis, reticulonodular opacities, bullae and cavitation), musculoskeletal (sacroilitis, bamboo spine, bony erosion (spine) and enthesitis) and cardiac (aortic valve insufficiency and aortitis) complications to name a few.

The hilum overlay sign occurs when a mass arises in the anterior mediastinum and the hilar vessels are seen through the mass, meaning that the mass does NOT arise from the hilum. Due to the anatomy of the mediastinum most of these masses will lie in the anterior mediastinum. Widened paratracheal stripe, Lateral doughnut sign and AP window mass are seen with middle mediastinal masses. Widened paravertebral stripe is seen in posterior mediastinal masses.

There are new guidelines from the British Thoracic Society for the investigation and management of pulmonary nodules (2015). They have produced a lengthy document, but the first few pages provide a summary of the recommendations, with flow-charts to help guide management. The guidelines overall aim to help reduce imaging follow-up. There is also a focus on using volumetric analysis of nodules, and calculating the risk of a nodule being malignant using a risk calculator (link provided in the references). They want to standardise the diagnostic approach for nodules detected incidentally and those that are found during screening.

Nodules with a maximum diameter of <5mm do not get followed up (instead of 4mm with the old Fleischner Guidelines). Nodules with a maximum diameter between 5 - 6mm get a CT at 1 year. Those between 6 - 8mm get a CT at 3 months. When these follow-up CTs are performed, ideally volumetrics should be calculated, and further follow-up guided by the volume doubling time (VDT). Those with a maximum diameter of >8mm get their risk calculated using the Brock Model Risk calculator (provided on the BTS website). The flow charts then determine follow-up based on the risk of malignancy calculated. If it has a malignant risk of <10%, then a CT in 3 months is advised. If it has a risk >10%, then a PET may be appropriate.

This particular nodule has a maximum diameter of 5mm. Therefore we should repeat CT at 1 year. If the size is stable using volumetry, then the patient can be discharged. If it is measured using only the 2D diameter and shown to be stable, then a further follow-up CT in another 12 months is recommended. This demonstrates the emphasis of the new guidelines on volumetric measurements. Under old guidance (Fleischner society guidelines) the average size of this nodule would be calculated (5mm in this case), which for a high risk patient such as this would mean follow up CTs at 6-12 & 18-24 months.ReferencesBritish Thoracic Society Guidelines
https://www.brit-thoracic.org.uk/document-library/clinical-information/p...

British Thoracic Society Risk Calculator
https://www.brit-thoracic.org.uk/guidelines-and-quality-standards/pulmon...

On size criteria alone this tumour would be T2a. Chest wall invasion and nodules within the same lobe upgrade the tumour to T3.