BASICS OF HRCT PART 6 - DISTRIBUTION PATTERN AND ADDITIONAL FEATURES

Upper lung zone preference is seen in:

• Inhaled particles: pneumoconiosis (silica or coal)
• Smoking related diseases (centrilobular emphysema
• Respiratory bronchiolitis (RB-ILD)
• Langerhans cell histiocytosis
• Hypersensitivity pneumonitis
• Sarcoidosis

Lower zone preference is seen in:

• UIP
• Aspiration
• Pulmonary edema

Central distribution is seen in sarcoidosis and cardiogenic pulmonary edema.

Peripheral distribution is mainly seen in cryptogenic organizing pneumonia (COP), chronic eosinophilic pneumonia and UIP.

Additional findings

Pleural effusion is seen in:

1.     Pulmonary edema

2.     Lymphangitic spread of carcinoma - often unilateral

3.     Tuberculosis

4.     Lymphangiomyomatosis (LAM)

5.     Asbestosis

Hilar and mediastinal lymphadenopathy

In sarcoidosis the common pattern is right paratracheal and bilateral hilar adenopathy ('1-2-3-sign').
In lung carcinoma and lymphangitic carcinomatosis adenopathy is usually unilateral.
'Eggshell calcification' in lymph nodes commonly occurs in patients with silicosis and coal-worker's pneumoconiosis and is sometimes seen in sarcoidosis, postirradiation Hodgkin disease, blastomycosis and scleroderma .

read other posts in this series

• CHEST X RAY INTERPRETATION

• CHEST X RAY PART 1- NORMAL ANATOMY AND ITS VARIANTS

• BASICS OF CHEST X RAY- PART 2 , EASY WAY TO INTERPRET CXR.

• BASICS OF CHEST X RAY PART 3- SYSTEMATIC APPROACH, SILHOUETTE SIGN AND HIDDEN AREAS IN CHEST XRAY

• BASICS OF CHEST X RAY-PART 4, THE HEART AND PERICARDIUM

• BASICS OF CHEST X RAY-PART 5, THE HILUM AND MEDIASTINUM

• BASICS OF CHEST X RAY PART-6, THE LUNGS, PLEURA AND THE CHEST WALL.

• BASICS OF HRCT INTERPRETATION

• BASICS OF HRCT INTERPRETATION-PART 2- RETICULAR PATTERN

• BASICS OF HRCT INTERPRETATION-PART 3- NODULAR PATTERN

• BASICS OF HRCT PART-4 , HIGH ATTENUATION PATTERN

• BASICS OF HRCT PART 5- LOW ATTENUATION PATTERN

• BASICS OF HRCT PART 6 - DISTRIBUTION PATTERN AND ADDITIONAL FEATURES

• BASICS OF HRCT PART 7 - DIFFERENTIAL DIAGNOSIS OF INTERSTITIAL LUNG DISEASE

• HRCT FINDINGS OF ATYPICAL ADENOMATOUS HYPERPLASIA.

• SARCOIDOSIS- CT FINDINGS

• MOUNIER KUHN SYNDROME

• AIR BRONCHOGRAM SIGN

• THE ‘DARK BRONCHUS’ SIGN

• THE RINGS !!!THE TRAMS!!!, CHEST X RAY FINDINGS IN BRONCHIECTASIS

• THE HRCT FINDINGS OF BRONCHIECTASIS.

• GRAND ROUNDS- CANNON BALL SECONDARIES AND PULMONARY METASTASIS...

• GRAND ROUNDS - OPAQUE HEMITHORAX.

• RADIOLOGY- CHEST X RAY SPOTTERS.

• CLINICAL CASE - GIVE YOUR DIAGNOSIS!!!

• SPOTTER : IDENTIFY THE RADIOLOGICAL SIGN IN CHEST X RAY 

• CHEST X RAY- IMPORTANCE OF DIAPHRAGM. THE DIAPHRAGM IS UNIQUE AND PROVIDES 

PLEURAL EFFUSION

Fluid accumulation in pleural space.

Clinical Picture

• Patients present with shortness of breath and cough.
• Can be asymptomatic and recognized on routine CXR.
• Dullness with decreased breath sounds and mediastinal shift can be seen.
• Chest x-ray shows fluid in pleural space with classical meniscus. Additional findings will depend on the etiology.

Etiology

Multiple etiologies can give rise to pleural effusion. Following are the common.

• Congestive heart failure
• Malignancy
• Parapneumonic
• Tuberculosis
• Rheumatoid arthritis

Pathophysiology

Mechanisms leading to accumulation of fluid in pleural spaces vary. Following are some.

• Increased hydrostatic pressure eg CHF.
• Increased capillary permeability eg malignancy
• Direct extravasation eg Chylothorax
• Negative pressure induced eg trapped lung

Diagnosis

• Pleural effusions are categorized as exudates and transudates.
• Thoracentesis is essential to obtain fluid for appropriate studies based on the clinical setting.
• Malignancy is the most common cause of exudative effusions and should be ruled out with cytological exam.
• In undiagnosed effusions one have to consider pleural biopsy either by blind method or by thoracoscopy.

Treatment

• Appropriate specific therapy based on the etiology.
• Therapeutic thoracentesis may be required to relieve shortness of breath.
• Pleural sclerosis will be a consideration in malignant effusions to prevent recurrence.