The azygos lobe clinical implications and an unusual variant joseph m. Azygos vein abutting the posterior wall of the right main. Its actually a congenital failure of normal migration of the azygos vein from the chest wall to its place above the tracheobronchial angle. Embryologically, it arises from an anomalous lateral course of the azygos vein 1 in a pleural septum within the apical segment of the right upper lobe or in other words an azygos lobe is formed. In 1877, azygos lobe was first described by heinrich wrisberg. Azygos anterior cerebral artery radiology reference. It occurs when the right posterior cardinal vein, one of the precursors of the azygos. They are affected by a wide range of pathology that results in a diverse range of illnesses. We use cookies to offer you a better experience, personalize content, tailor advertising, provide social media features, and better understand the use of our services.
It is important to have a good understanding of the entity, as it can mimic certain pathological conditions like bullae, abscesses or lung masses. The congenital azygous lobe with its suspensory azygous web is an anatomic variant that can obscure visualization of the superior sulcus of the right hemithorax during various thoracic surgical procedures. Current anatomy textbooks do not mention the azygos lobe at all. Normally, the thoracic portion of the azygos vein is derived from the right posterior cardinal vein and arches over the apex of the right lung, draining towards the superior vena cava. Right posterior cardinal vein precursor of azygos vein fails to migrate over lung apex, instead penetrating the lung and carrying pleural layers with it. A 55 year old male presented with a complaint of dyspnea and non productive cough. Four patients who underwent thoracoscopic sympathicotomy for massive palmoplantar hyperhidrosis were discovered to have this irregularity. Azygos lobe is a very rare but normal anatomic variant of right upper lobe seen in only 0. An azygos fissure is seen on approximately 12% of chest xrays autopsy studies suggest they are more common.
Its radiological aspects are well known but there are few anatomical reports about. Azygos arch crosses right upper lobe bronchus 3 and. A rare cause of right paratracheal opacity sciencedirect. He was found to have right paratracheal opacity on chest x ray. A rare case of an azygos lobe in the right lung of a 40.
The azygos lobe is a rare anatomical variant, most often encountered in the right lung 12. A normal variant is an atypical finding that is seen in a percentage of the population, which generally has no clinical significance, and is considered within the spectrum of normal findings. The azygos lobe is an anatomical variant that deserves special attention because it is found in at least 1% of chest radiographs. The four layers of pleura are then known as the azygos fissure, and the bit of lung tissue separated from the rest of the lung is known as the azygos lobe. Azygos fissure, vein, and lobe azygos fissure represents one of the accessory fissures of lung, which is a normal developmental variant. As an anatomical variation in 12% of the population, the arch can be displaced laterally, thereby creating a pleural septum separating an azygos lobe from the upper lobe of the right lung. The azygos lobe is a normal variant that is found in 1% of anatomic specimens and on about 0.
Normal variant, found in 1% of anatomic specimen and about 0. An azygos lobe is a rare congenital variant of the right lung, usually diagnosed as an incidental finding. Thoracoscopic surgery for hyperhidrosis in the presence of. As a result, there is no anterior communicating artery. Awareness of this anatomical variant and its characteristic xray features is. Scroll down to view images of normal anatomical variants. An azygos anterior cerebral artery is an uncommon to rare variant of the circle of willis where the two a1 segments of the anterior cerebral artery aca join to form a single trunk. The azygos lobe is created when a laterally displaced azygos vein makes a deep fissure in the upper part of the lung. The azygous lobe is a normal anatomical variant with reported incidence of 0. We describe the signs that allow identification of such variants and the role of ct in explaining the findings and excluding a. Anatomy, thorax, lung azygos lobe statpearls ncbi bookshelf. It is important to report and document the different variations of the azygos venous system because especially in ct and mri scans.
On a chest film it is seen as a fine line that crosses the apex of the right lung. The azygos lobe is a rare anatomical variant, most often encountered in the right lung. The presence of an azygos fissure, associated with collapse of the right upper lung lobe, may allow the displacement of the azygos vein outside the azygos fissure. The azygos lobe is a rare anomaly that developmentally arises when the right posterior cardinal vein penetrates the apex of the lung, instead of passing over it, and travels inferiorly taking pleural layers with it to entrap a portion of the right upper lobe. This organization is similar to that seen in lower primates 2. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks. The azygos vein, which is lined by visceral and parietal pleura, lies in the base of the fissure. Medially there is a small connection of the azygos lobe with the rest of the upper lobe. It is also important in preparation for surgical procedures. An azygos lobe is an unusual but important anatomical variant of the right lung anatomy 1,2. Click on an image to see a full larger version with arrows. They contain 1500 miles of airways, 300500 million alveoli and have a combined surface area of 70 square meters half a tennis court. The azygos lobe imaging is amazinginteresting cases. Azygos lobe of right lung information including symptoms, causes, diseases, symptoms, treatments, and other medical and health issues.
Heinrich wrisberg first recognized it during a postmortem exam in 1877 and it was first described on the chest radiograph in 1923 1,3. The azygos vein itself is seen on end, and may simulate a pulmonary mass. Overview of anatomy and pathophysiology of lung cancer. An azygos lobe is a normal anatomic variant of the right upper lobe due to invagination of the azygos vein and pleura during embr yological development in the fetus. The clinical importance of an azygos lobe is that it can become consolidated with infection and mimic a lung mass.
It occurs when the right posterior cardinal vein, one of the precursors of the azygos vein, fails to migrate over the apex of the lung and penetrates it instead, carrying along pleural layers that entrap a portion of the right upper lobe. This arch of the azygos vein arcus venae azygos is an important anatomic landmark. An azygos lobe is created when a laterally displaced azygos vein creates a deep pleural fissure into the apical segment of the right upper lobe during embryological development. Terminology spelling it hemiazygous when referring to the vein is incorrect, regardless of whether british or american english 7. Prenatal diagnosis of a variant of the azygos venous system. It is a normal anatomic variant of the right upper lobe due to invagination of the azygos vein and pleura during development in the fetus.
Found as an anatomic variant in about 1% of people, the azygos lobe forms when the posterior cardinal vein, instead of remaining along the apex of the lung, penetrates the upper medial portion of the apical segment of the right upper lobe. Azygos lobe al is a rare normal anatomic variant of the lung with a frequent location at the right upper lobe. Ihe azygos lobe is a now commonly recognized congenital anomaly of the upper lobe of the lung. The azygos lobe is a rare anomaly in bronchopulmonary segmentation due to an unusual course of the azygos vein. The azygous lobe formation is a benign process and is often found incidentally. Azygos lobe definition of azygos lobe by medical dictionary. The vein remains in the substance of the lungs but as the upper lobe develops inferiorly to superiorly, a double fold of visceral pleura two layers of visceral pleura and two layers of parietal pleura develops. In human anatomy, an azygos lobe is a normal anatomical variation of the upper lobe of the right lung.
Cureus a rare case of an azygos lobe in the right lung. This reports describes the presence of azygous lobe, a rare anatomical variant, encountered during. An azygos lobe is a rare congenital variant usually of the right lung, not a true separate lobe. We describe the signs that allow identification of such variants and the role of ct in explaining the findings and excluding a pathological process. A normal anatomic variant includes the presence of an azygos lobe see fig. Some variations of the azygos venous system can easily be confused with pathological conditions such as aneurysms, tumors and enlarged lymph nodes. The hemiazygos vein is the asymmetric counterpart to the azygos vein and forms part of the azygos venous system. In this paper we describe the normal appearance of the azygos lobe on conventional radiography and ct, presenting variants that may simulate pathology on the chest radiograph. An azygos lobe is a rare, anatomical variant of the upper lobe of the right lung. The invaginated visceral and parietal pleural layers persist to form a fissure. The azygos vein freely anastomoses with the vertebral venous plexus.
Low this article has been rated as lowimportance on the. Its demarcating fissure contains both visceral and parietal pleural layers. Its etiology is related to a defect of the migration of the azygos vein during the embryonic development. An azygos lobe is a rare variant of normal anatomy, seen in approximately 12% of the population. Start this article has been rated as startclass on the projects quality scale. The lungs are the functional units of respiration and are key to survival. This normal variant consists of the upper right lung developing around the azygos vein. We use cookies to give you the best possible experience on our website. We report a case of a 51yearold man with past medical history significant for drug and alcohol abuse, who presented to the emergency department with altered mental status and hypoxic respiratory failure.
Clinically, the azygos lobe has been accepted as a normal variation that can. A cadaver with azygos lobe and its clinical significance. This small variant lobe is separated from the upper lobe by a deep fissurelike groove that cradles the azygos. The azygous lobe found in the south african population. This book is distributed under the terms of the creative commons. This organization is similar to that seen in lower primates 2 epidemiology. The azygos lobe is a normal variant of pulmonary anatomy, present in 0. Azygos lobe is formed when a displaced right posterior cardinal vein penetrates.
This is relatively unusual, as most elements of anatomy reflect bilateral symmetry. Azygos fissure as seen on a pa chest radiograph normal variant. Another term for the same concept is impar wellknown structures incorporating this nomenclature include the azygos vein and ganglion impar also azygos lobe, refers to a normal variant shown in the right upper medial lung. A small lobe sometimes found on the upper part of the right lung, formed by an infolding of the pleura and separated from the rest of the upper lobe by a deep groove lodging the azygos vein. By continuing to use this site you consent to the use of cookies on your device as described in our cookie policy unless you have disabled them. Media in category human anatomy, azygos lobe the following 22 files are in this category, out of 22 total. This anatomical variant azygous lobe can also be visible on ct imaging, as a thickened fissure from the posterior vertebral body extending to the superior vena cava. An azygos lobe is an accessory lobe of the lung that may occasionally be confused with a. In the embryo the right posterior cardinal vein, part of which persists as the azygos vein. This normal variant is often seen on ap lower cervical views, as was the situation with this particular case.