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Thorax 3 (Lung (areas of increased density (most common) - opacities…
Thorax 3
Lung
- on CXR lung abnormalities are areas of decreased density - lucencies. OR areas of increased density (most common) - opacities
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sarcoidosis*
- systemic disease with unknown origin.
- four stages of chest films: bilateral hilarity lymphadenopathy, bilateral hilarity lymphadenopathy+ pulmonary disease, only pulmonary disease, irreversible fibrosis
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Mediastinum, pleura and chest wall
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Neurogenic tumors
- Usually are found in the posterior mediastinum
- Approximately 30 % are malignant
- CT typically shows a paravertebral mass, ellipsoidal or dumbbell-shaped; may cause expansion of an intervertebral foramen
- Foci of bone destruction without sclerotic borders indicate malignancy
- Most neurogenic tumors have an oval shape and are homogeneous soft-tissue attenuation
Lymph node enlargement
- CT is currently the technique of choice for evaluating the status of the mediastinal and hilar lymph nodes
- Lymph nodes can be identified on CT when are 2-5 mm in diameter
- The differentiation between benign and malignant LN is difficult because node size is the only criterion available on CT scans
- When a short axis nodal diameter of 1 cm is taken as a threshold, CT is approximately 60% sensitive and 70% specific in detecting malignant involvement
- Micrometastases are found in 5-15% of normal size lymph nodes
- 15-30% of moderately enlarged lymph nodes (10-15 mm) are free of metastases
- The most frequent inflammatory causes of mediastinal lymph node enlargement are fungal infections and tuberculosis
- Most mediastinal lymph nodes are hypoattenuating relative to the mediastinal vessels
Pancoast Tumor
- Bronchial carcinoma arising in the apex of the lung
- The typical clinical manifestation are caused by invasion of the brachial plexus (shoulder and arm pain) or the sympathetic chain (Horner’s syndrome)
- CT: PT has a strong propensity for invading the ribs, vertebral column esophagus, trachea, brachiocephalic vessels and cervical soft tissues
Bronchial carcinoma
- The most frequent tumor in the statistics of neoplasm-related death rates
- The commonest tumor of the central tracheobronchial system
- The most frequent histological types:
adenocarcinoma (30%), squamous cell carcinoma (25%), small-cell carcinoma (20%), large cell carcinoma (10%)
- characterized by early lymphogenous and hematogenous spread
- Lymph node metastases are commonest with small-cell carcinomas
- The highest rates of metastases are to the:
liver and adrenals (up to 40%), brain (up to 43%), bone (up to 33%)
abdominal lymph nodes (up to 30%), kidneys (up to 25%)
staging
- Useful in selecting patients for surgical resection, planning radiotherapy and monitoring the response to chemotherapy
- Stages I and II are acceptable to resection
- Stage III is divided into two classes:
IIIA includes with limited mediastinal or chest wall invasion and are potentially resectable
IIIB is considered non-resectable
TNM staging
- T0 – no direct evidence of primary tumor
- T1 – intrapulmonary tumor ≤ 3 cm, surrounded by lung parenchyma or visceral pleura, no infiltration of the intermediate or main bronchi
- T2 – tumor > 3 cm, or tumor involving the intermediate or main bronchus but at least 2 cm distal to the carina, or tumor involving the visceral pleura
- T3 – tumor of any size involving the main bronchus within 2 cm of the carina, or tumor directly invading the parietal or mediastinal pleura, diaphragm, chest wall, or pericardium
- T4 – tumor of any size invading the heart, great vessels, trachea, carina, esophagus, or spinal column, or the presence of malignant pleural effusion, satellite lesions within the same lobe as primary tumor
- N0 – no metastasis to regional lymph nodes
- N1 – metastasis to ipsilateral bronchial or hilar lymph nodes
- N2 – metastasis to ipsilateral mediastinal and subcarinal lymph nodes
- N3 – metastasis to scalene or supraclavicular lymph nodes, or metastasis to contralateral mediastinal or hilar lymph nodes
- M1 – distant metastases, satellite lesions in different lobe as primary tumor (ipsi – or contralateral)
Metastases
- Pulmonary metastases most commonly originate from carcinomas of the: breast, kidneys, colon, stomach, pancreas, seminomas and sarcomas
- CT is the most sensitive modality for detecting metastases in the staging of tumors
- Spiral CT can detect pulmonary nodules as small as 2-3 mm in diameter
CT morphology
- Metastases typically have smooth margins
- A mass with ill-defined margins should raise suspicion of a peripheral bronchial carcinoma
- Solitary metastases are rare, accounting for just
5 % of all solitary nodules
- The likelihood that pulmonary nodules are metastatic increase with the numbers of the of nodules that are seen
- Metastases are commonest in the outer portion of the lung (90%) and near the pleura; predominantly involve the lower lobes (66%)
- 40% of metastases are found to have associated blood vessels (feeding vessel sign)
- Calcifications are rare and generally suggest benignancy, although calcified metastases are known to arise from: osteosarcoma, chondrosarcoma (less commonly), Mucous-forming adenocarcinoma – breast, colon, ovary (rarely), thyroid carcinoma , soft-tissue sarcomas, after chemotherapy
- silhouette sign: loss of normal inter faces due to lung pathology (consolidation, atelectasis, mass), which can be used to localize disease in specific lung segments; note that pleural or mediastinal disease can also produce the silhouette sign)
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