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KEY FACTS
Terminology
Imaging
Top Differential Diagnoses
Pathology
Clinical Issues
Diagnostic Checklist
TERMINOLOGY
Synonyms
- Azygos fissure
Definitions
- Anomalous intrapulmonary course of azygos vein that creates accessory fissure
- Includes 4 layers of non-fused parietal and visceral pleura (mesoazygos) invaginated into medial right upper lobe (RUL)
- Vertical or curved oblique course of fissure
- Teardrop-shaped lower margin contains azygos vein
- Trigone
- Cranial aspect of fissure (triangular shape); determines size of lung medial to fissure
- Included lung shape classified based on trigone position
- Type A: Trigone located in lateral aspect of pulmonary apex
- Type B: Trigone located at mid point of apex; fissure is relatively vertically oriented
- Type C: Trigone located medially; fissure curves toward mediastinum
- Fissure length varies with type: Longer in type A, shorter in types B and C
- Accessory fissure of variable size borders medial aspect of RUL
- Anomalous intrapulmonary course of azygos vein that creates accessory fissure
IMAGING
Imaging Recommendations
Radiographic Findings
CT Findings
DIFFERENTIAL DIAGNOSIS
PATHOLOGY
General Features
CLINICAL ISSUES
Presentation
Demographics
DIAGNOSTIC CHECKLIST
Image Interpretation Pearls
Selected References
- Bostanci K et al: Variations in pulmonary fissural anatomy: a medicolegal autopsy study of 256 cases. ANZ J Surg. 90(4):608-11, 2020
- Semionov A et al: Migration of the azygos vein from the azygos fissure to the mediastinum. Radiol Case Rep. 14(6):763-5, 2019
- Taydas O et al: Reentrance of azygos vein into azygos fissure after pneumothorax. Eurasian J Med. 49(1):62-3, 2017
- Suwatanapongched T et al: Visibility and variability of pleural fissures on normal digital chest radiographs of 1,000 healthy adults. Jpn J Radiol. 33(4):201-9, 2015
- Lenoir V et al: The empty azygos fissure. J Radiol Case Rep. 7(4):10-5, 2013
- Villanueva A et al: Migrating azygos vein and vanishing azygos lobe: MDCT findings. AJR Am J Roentgenol. 194(3):599-603, 2010
- Maldjian PD et al: The empty azygos fissure: sign of an escaped azygos vein. J Thorac Imaging. 23(1):54-6, 2008
- Hayashi K et al: Radiographic and CT appearances of the major fissures. Radiographics. 21(4):861-74, 2001
- Shin MS et al: Clinical significance of azygos vein enlargement: radiographic recognition and etiologic analysis. Clin Imaging. 23(4):236-40, 1999
- Caceres J et al: The azygos lobe: normal variants that may simulate disease. Eur J Radiol. 27(1):15-20, 1998
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References
Tables
Tables
KEY FACTS
Terminology
Imaging
Top Differential Diagnoses
Pathology
Clinical Issues
Diagnostic Checklist
TERMINOLOGY
Synonyms
- Azygos fissure
Definitions
- Anomalous intrapulmonary course of azygos vein that creates accessory fissure
- Includes 4 layers of non-fused parietal and visceral pleura (mesoazygos) invaginated into medial right upper lobe (RUL)
- Vertical or curved oblique course of fissure
- Teardrop-shaped lower margin contains azygos vein
- Trigone
- Cranial aspect of fissure (triangular shape); determines size of lung medial to fissure
- Included lung shape classified based on trigone position
- Type A: Trigone located in lateral aspect of pulmonary apex
- Type B: Trigone located at mid point of apex; fissure is relatively vertically oriented
- Type C: Trigone located medially; fissure curves toward mediastinum
- Fissure length varies with type: Longer in type A, shorter in types B and C
- Accessory fissure of variable size borders medial aspect of RUL
- Anomalous intrapulmonary course of azygos vein that creates accessory fissure
IMAGING
Imaging Recommendations
Radiographic Findings
CT Findings
DIFFERENTIAL DIAGNOSIS
PATHOLOGY
General Features
CLINICAL ISSUES
Presentation
Demographics
DIAGNOSTIC CHECKLIST
Image Interpretation Pearls
Selected References
- Bostanci K et al: Variations in pulmonary fissural anatomy: a medicolegal autopsy study of 256 cases. ANZ J Surg. 90(4):608-11, 2020
- Semionov A et al: Migration of the azygos vein from the azygos fissure to the mediastinum. Radiol Case Rep. 14(6):763-5, 2019
- Taydas O et al: Reentrance of azygos vein into azygos fissure after pneumothorax. Eurasian J Med. 49(1):62-3, 2017
- Suwatanapongched T et al: Visibility and variability of pleural fissures on normal digital chest radiographs of 1,000 healthy adults. Jpn J Radiol. 33(4):201-9, 2015
- Lenoir V et al: The empty azygos fissure. J Radiol Case Rep. 7(4):10-5, 2013
- Villanueva A et al: Migrating azygos vein and vanishing azygos lobe: MDCT findings. AJR Am J Roentgenol. 194(3):599-603, 2010
- Maldjian PD et al: The empty azygos fissure: sign of an escaped azygos vein. J Thorac Imaging. 23(1):54-6, 2008
- Hayashi K et al: Radiographic and CT appearances of the major fissures. Radiographics. 21(4):861-74, 2001
- Shin MS et al: Clinical significance of azygos vein enlargement: radiographic recognition and etiologic analysis. Clin Imaging. 23(4):236-40, 1999
- Caceres J et al: The azygos lobe: normal variants that may simulate disease. Eur J Radiol. 27(1):15-20, 1998
