SHORT TALK ABOUT DIFFERENTIAL DIAGNOSIS BILATERAL HYPERLUCENT LUNGS , COMMON AND LESS COMMON CAUSES WITH CLUES TO DIAGNOSIS AND SOME EXAMPLES HOPPING YOU LIKE IT DR HISHAM ALKHATIB CONSULTANT RADIOLOGIST

1. Bilateral Hyperlucent
Hemithorax
Hisham AlKhatib, M.D.
Consultant Radiologist

2. •‫اله‬ ‫وعلى‬ ‫هللا‬ ‫رسول‬ ‫على‬ ‫والسالم‬ ‫والصالة‬ ‫هلل‬ ‫الحمد‬
‫اجمعين‬ ‫م‬ّ‫ل‬‫وس‬ ‫وصحبه‬
•، ‫علما‬ ‫وزدني‬ ‫ينفعني‬ ‫بما‬ ‫وعلمني‬ ‫علمتني‬ ‫بما‬ ‫انفعني‬ ‫اللهم‬
‫الحكيم‬ ‫العليم‬ ‫انك‬
• Praise be to Allah and prayers be upon the
Messenger of Allah and his family and
companions.
• Oh God, give me the benefit of what you
have taught me and teach me what benefits
me.

3. ESSENTIAL INFORMATION

4. Key Differential Diagnosis Issues
• Pulmonary causes
– Usually related to airways disease
– Pulmonary vascular causes much less common
• Extrapulmonary causes
– Congenital or developmental lack of chest wall
soft tissue
– Bilateral mastectomy

5. Key Differential Diagnosis Issues
• Technical
– Overexposure
• Uncommon with digital radiography
– Incorrect window and level settings on CT

6. DIFFERENTIAL DIAGNOSIS

7. Common Causes
• Centrilobular Emphysema
• Panlobular Emphysema
• Bronchiectasis
• Bronchiolitis

8. Helpful Clues for Common
Diagnoses

9. Centrilobular Emphysema
– Most common type of emphysema
– Almost always smoking related
– Predominates in upper lobes and superior
segments of lower lobes
– Radiography: Hyperinflation, attenuation of
vessels in affected areas
– CT: Centrilobular foci of low attenuation without
perceptible walls
– Bulla: Emphysematous space > 1 cm

12. Panlobular Emphysema
– Most commonly associated with α-1-antitrypsin
deficiency
– Rarely associated with intravenous drug abuse
(e.g., methylphenidate [Ritalin])
– Predominates in basal portions of lungs

13. Panlobular Emphysema
– Radiography
• Hyperinflation
• Attenuation of vessels in affected areas, particularly
lower lung zones
– CT
• Hyperinflation, particularly of lower lobes
• Diffusely decreased attenuation of affected lung
parenchyma with small vessels

16. Bronchiectasis
– Hyperinflation and air-trapping from associated
small airways disease
– Related to chronic or recurrent infection
• Rarely result of congenital cartilage abnormality
(Williams-Campbell syndrome)

17. Bronchiectasis
– Radiography
• Pulmonary hyperinflation
• Dilated bronchi
• “Tram-tracking”: Parallel lines representing nontapering
walls of ectatic bronchi seen in profile
• Mucoid impaction may be present

18. Bronchiectasis
– CT
• Bronchial abnormalities clearly shown
• Diffuse low attenuation and small vessels often present
in parenchyma supplied by dilated and inflamed
bronchi
• Extensive air-trapping may be apparent on expiratory
CT

21. Bronchiolitis
– Usually infectious
• Viral
• Mycoplasma
– Radiography: Hyperinflation, small lung nodules
– CT: Centrilobular nodules, tree in bud opacities

23. Less Common Causes
• Constrictive Bronchiolitis
• Asthma
• Pulmonary Langerhans Cell Histiocytosis
• Lymphangiomyomatosis

24. Helpful Clues for Less Common
Diagnoses

25. Constrictive Bronchiolitis
– Submucosal and peribronchial fibrosis resulting in
luminal narrowing or occlusion
– Numerous causes
• Infection: Viral (adenovirus and respiratory syncytial
virus), Mycoplasma, Pneumocystis
• Connective tissue diseases, especially rheumatoid
arthritis and Sjögren syndrome
• Drug reaction
• Inhalational injury (toxic fumes, smoke)
• Transplant: Lung and blood stem cell

26. Constrictive Bronchiolitis
– Radiography: Normal lung volume to
hyperinflation
– CT: Heterogeneity of lung with smaller vessels in
areas of low attenuation
• Expiratory imaging confirms presence of air-trapping

28. Asthma
– Chronic airway inflammation with remodeling
– Radiography
• Most patients have normal or near normal radiographs
• Bronchial wall thickening may be evident
• Pulmonary hyperinflation in severe cases

29. Asthma
– CT
• Bronchial wall thickening
• Bronchial luminal narrowing
• Air-trapping (expiratory CT)
• Allergic bronchopulmonary aspergillosis should be
considered with central bronchiectasis and mucoid
impaction

31. Pulmonary Langerhans Cell
Histiocytosis
– Nearly all patients are smokers
– Radiography
• Hyperinflation
• Reticular or reticulonodular abnormality sparing
costophrenic sulci

32. Pulmonary Langerhans Cell
Histiocytosis
– CT
• Upper lobe predominant cysts: Vary in size and shape
• Small nodules ± central lucency progressing to cysts
over time
• Ground-glass opacity
– Spontaneous pneumothorax in < 10%

35. Lymphangiomyomatosis
– Occurs exclusively in women of child-bearing age
or patients with tuberous sclerosis
– Radiography
• Hyperinflation
• Diffuse reticular abnormality (from superimposition of
cysts)
• Pleural effusion (chylous)

36. Lymphangiomyomatosis
– CT
• Diffuse lung cysts ranging 2-20 mm with thin, smooth
walls
• Associated findings: Renal angiomyolipomas,
retroperitoneal and mediastinal lymphangiomas,
chylous pleural effusion
– Patients may present with recurrent or chronic
pneumothoraces

39. Rare but Important
• Pulmonary Atresia

40. Helpful Clues for Rare Diagnoses

41. Pulmonary Atresia
– Presents in neonatal period: Cyanosis
– Associated with other congenital cardiac
malformations (e.g., tetralogy of Fallot)
– Radiography
• Cardiomegaly
• Concave pulmonary artery segment
• Pulmonary oligemia
– Diagnosis usually confirmed by echocardiography
or cardiac MR

43. THANK YOU