Central airway pathology: clinic features, CT findings with pathologic and virtual endoscopy correlation

Abstract

Objectives: To describe the imaging features of the central airway pathology, correlating the findings with those in pathology and virtual endoscopy. To propose a schematic and practical approach to reach diagnoses, placing strong emphasis on multidetector computed tomography (MDCT) findings.

Methods: We reviewed our thoracic pathology database and the central airway pathology-related literature. Best cases were selected to illustrate the main features of each disease. MDCT was performed in all cases. Multiplanar and volume-rendering reconstructions were obtained when necessary. Virtual endoscopy was obtained from the CT with dedicated software.

Results: Pathological conditions affecting the central airways are a heterogeneous group of diseases. Focal alterations include benign neoplasms, malignant neoplasms, and non-neoplastic conditions. Diffuse abnormalities are divided into those that produce dilation and those that produce stenosis and tracheobronchomalacia. Direct bronchoscopy (DB) visualises the mucosal layer and is an important diagnostic and therapeutic weapon. However, assessing the deep layers or the adjacent tissue is not possible. MDCT and post-processing techniques such as virtual bronchoscopy (VB) provide an excellent evaluation of the airway wall.

Conclusion: This review presents the complete spectrum of the central airway pathology with its clinical, pathological and radiological features.

Teaching points: • Dividing diseases into diffuse and focal lesions helps narrow the differential diagnosis. • Focal lesions with nodularity are more likely to correspond to tumours. • Focal lesions with stenosis are more likely to correspond to inflammatory disease. • Posterior wall involvement is the main feature in diffuse lesions with stenosis.

Keywords: Relapsing polychondritis; Respiratory tract diseases; Tracheal diseases; Tracheobronchomegaly; Tuberculosis.

Fig. 1

Endobronchial papilloma of a 50-year-old patient. (i) Contrast-enhanced CT scan of the chest in mediastinal window shows a mildly enhancing nodule (arrow). (ii) Lung window confirms its endobronchial origin (arrow). Diagnosis was made after resection. (iii) Photograph of the resected lung shows a polypoid irregular intrabronchial lesion. (iv) Photomicrograph (original magnification, ×2; haematoxylin-eosin stain) shows an exophytic lesion with benign keratinized squamous epithelium (stars) covering an irregular stroma (arrowheads)

Fig. 2

Hamartoma in a 62-year-old patient. (i) Contrast-enhanced CT scan showing a lesion (arrowhead) with popcorn-like calcification and fat-tissue attenuation, consistent with hamartoma. (ii) Endobronchial involvement produces air trapping in the anterobasal segment because of valve effect. (iii) Gross pathology specimen showing a multilobulated tumour lesion that combines adipose (arrowheads), cartilaginous (stars) and epithelial tissue invaginations (arrow) consistent with hamartoma. (iv) Same findings are shown in the photomicrograph (original magnification, 4×; haematoxylin-eosin stain)

Fig. 3

(i) Contrast-enhanced CT scan in a 55-year-old patient showing a nodule within the right main bronchus (arrowhead) with avid contrast enhancement, suggestive of a carcinoid tumour. After resection, pathological analysis (not shown) confirmed the diagnosis. (ii) Virtual bronchoscopy depicts the lesion

Fig. 4

Squamous cell carcinoma in a 63-year-old patient, a heavy smoker. (i) Axial CT scan shows a nodular lesion (arrowhead) located on the tracheal carina with an endoluminal and extraluminal component. (ii) Photomicrograph (original magnification, ×20; haematoxylin-eosin stain) shows infiltrating groups of atypical squamous epithelial cells (arrow), with necrotising material in the centre of the epithelial nest (star)

Fig. 5

Cystic adenoid carcinoma in a 44-year-old patient, with no smoking history. (i) Axial MDCT (arrowhead) shows an endoluminal mass with an extraluminal solid component that deforms the left side of the tracheal wall. (ii) Coronal MDCT reconstruction demonstrates that the longitudinal axis of the lesion is greater than the axial axis. These are the typical findings in a cystic adenoid carcinoma. After resection, pathological analysis confirmed the diagnosis. (iii) Photomicrograph (original magnification, ×4; haematoxylin-eosin stain) shows an extensive interstitial infiltration by groups of tumoral cells with pseudo-glandular pattern (arrowheads)

Fig. 6

Haemangiopericytoma. (i) Axial MDCT showing an intratracheal mass (arrowhead) with irregular margins, with no specific features. (ii) Volume-rendering reconstruction showing the important irregular stenosis. After surgery and pathological analysis, the diagnosis of haemangiopericytoma was made

Fig. 7

Lymphoma. (i) Coronal multiplanar reconstruction showing an endobronchial enhancing lesion in the left main bronchus (arrowhead) that produces an almost complete occlusion of the bronchus. (ii) Volume-rendering reconstruction better depicting the occlusion of the main left bronchus. Note the air trapping at the upper lobe of the left lung and the loss of volume of the inferior lobe (arrow). Histological analysis (not shown) yielded the diagnosis of lymphoma

Fig. 8

A 58-year-old patient with metastatic colon cancer. (i) Multiplanar coronal reconstruction showed a newly appeared small nodular lesion within the left bronchus wall (arrowheads), highly suggestive of progression of the disease. (ii) Virtual bronchoscopy showed more irregularities in the bronchus wall

Fig. 9

Tuberculosis in the left main bronchus of a 31-year-old female. (i) Axial MDCT scan shows a significant stenosis of the main left bronchus, without the presence of a mass. (ii) Coronal MinIP reconstruction shows a short area of stenosis located at the left main bronchus (arrow)

Fig. 10

A 20-year-old patient developed dyspnoea after a long period of intubation. MDCT was performed. (i) Multiplanar coronal reconstruction and (ii) volume rendering showing stenosis in the upper trachea (arrowhead). Planimetry, not shown, yielded stenosis of 54%. (iii) Virtual bronchoscopy showing the lesion

Fig. 11

A 51-year-old female with a long history of progressive dyspnoea and stridor. (i) Multiplanar sagittal reconstruction showing a severe subglottic stenosis (arrowhead). (ii) Lateral view of a volume-rendering reconstruction of the same study. No other causes were found, and an exclusion diagnosis of idiopathic stenosis was made

Fig. 12

Inflammatory pseudotumour in the left main bronchus of a 50-year-old male, with a history of cough and wheeze for about 6 months. (i) Axial MDCT scan in the pulmonary window, showing a partially occlusive endobronchial nodule, located on the left main bronchus. (ii) Bronchoscopic image shows a hypervascular lesion, obstructing 95% of the bronchial lumen of the left main bronchus. Final diagnosis was made after resection. (iii) Photomicrograph (original magnification, ×4; haematoxylin-eosin stain) demonstrates an inflammatory infiltrate, composed mainly of myofibroblasts, characteristic of inflammatory pseudotumour

Fig. 13

A 17-year-old male after a motorbike crash. MDCT scan and multiplanar coronal reconstruction showing complete rupture of the inferior lobe of the bronchus (arrow) causing pneumomediastinum (arrowhead) and pneumothorax. Areas of consolidation due to contusion are also seen in the upper as well as inferior lobes

Fig. 14

Mounier-Kuhn syndrome in a 45-year-old patient with a long history of lower respiratory tract infections. (i, ii) Axial and coronal MDCT scan, showing significant tracheobronchial dilatation and central bronchiectasis, both typical findings of Mounier-Kuhn syndrome

Fig. 15

Acquired tracheobronchomegaly in a 72-year-old patient with a history of treated tuberculosis. (i) Axial MDCT shows tracheal dilatation, bronchiectasis, and tuberculosis sequelae, with a dense band and a calcification in the right superior lobe

Fig. 16

Tracheal rhinoscleroma in a 47-year-old male. (i) Axial MDCT scan shows a concentric irregular thickening of the trachea wall without evident calcifications. (ii) Sagittal MDCT scan demonstrates diffuse irregular narrowing of the tracheal wall, including the posterior. (iii) Bronchoscopy shows nodular plaques on the mucosal surface of the trachea

Fig. 17

Tracheal amyloidosis in a patient with a history of pulmonary amyloidosis and episodic dyspnoea. (i) Coronal MDCT scan shows tracheal nodules protruding into the tracheal lumen, which has calcifications. (ii) Axial MDCT scan demonstrates the nodular affectation and the compromised posterior tracheal wall. (iii) Virtual endoscopy shows diffuse nodular narrowing of the tracheal lumen

Fig. 18

Tracheobronchial granulomatosis with polyangitis in a 57-year-old patient with a long history of multisystemic disease. (i) Axial MDCT scan shows a diffuse thickening of the bronchial wall, including the posterior wall, which helps to differentiate it from polychondritis. (ii) Coronal VRT reconstruction demonstrates stenosis on the subglottic area and left main bronchus. (iii) Photomicrograph (original magnification, ×20; haematoxylin-eosin stain) shows a necrotising granulomatous lesion with focal vascular destruction. The shape of the granuloma is elongated and the material in the necrotic centre has abundant nuclear debris

Fig. 19

Tracheal sarcoidosis in a 59-year-old female with a history of pulmonary sarcoidosis. (i) Axial MDCT scan shows diffuse and irregular trachea. (ii) Virtual bronchoscopy and (iii) direct bronchoscopy have excellent correlation. (iv) Photomicrograph (original magnification, ×2; haematoxylin-eosin stain) shows small epithelioid granulomas without necrosis

Fig. 20

Relapsing polychondritis of the trachea in a 51-year-old patient. (i) Axial MDCT shows wall thickening, sparing the posterior wall of the trachea. (ii) Coronal MDCT shows extensive compromise of the trachea. Note the high density of the thickening wall

Fig. 21

Tracheobronchopathia osteochondroplastica, as an incidental finding in a 63-year-old patient. (i) Axial MDCT scan shows an irregular thickening of the tracheal wall with calcifications and sparing the posterior wall. (ii) VRT reconstruction demonstrating the extension of the disease along the tracheal wall. (iii) Endoscopy demonstrated a nodular pattern without compromise of the posterior wall. (iv) Photomicrograph (original magnification, ×2; haematoxylin-eosin stain) shows chondroid and bony material (star) beneath the ciliated surface (arrows)

Fig. 22

Tracheobronchomalacia in a 67-year-old patient. (i) Inspiratory axial MDCT shows a normal tracheal diameter. (ii) Expiratory axial MDCT scan demonstrating collapse of the tracheal wall during expiration, characteristic of tracheobronchomalacia

Fig. 23

Schematic diagnostic approach to tracheobronchial focal lesions

Fig. 24

Schematic diagnostic approach of tracheobronchial diffuse lesions