Several axial images as well as two coronal images are provided demonstrating that there are multiple cysts of varying sizes within the pancreas. These cystic lesions demonstrate no overt to wall enhancement or nodular components. Notably there are no cysts identified within the kidneys or liver. No adrenal abnormalities are present.
The presence of multiple pancreatic cysts is a rare finding, particularly in the absence of other polycystic changes indicative of adult polycystic kidney disease (renal cysts and liver cysts are almost ubiquitous prior to pancreatic cyst development). The remaining differential for multiple pancreatic multiple cysts is extremely limited. This might include postinflammatory cysts which are usually associated with some form of acute or chronic inflammatory finding. Multiple intra papillary mucinous neoplasms could be considered, however, these are usually multilocular side branch communicating lesions. In the absence of cystic lesions elsewhere, the appearances are almost certainly due to von Hippel-Lindau (VHL) syndrome. VHL syndrome is associated in approximately 50% of cases with pancreatic cysts, representing the sole focus of disease of approximately 10% of cases. The precise incidents of cysts varies from family to family with VHL. The majority of these cases are asymptomatic. Cysts can replace the entirety of the pancreas, rarely associated with exocrine dysfunction. The cysts are commonly simple cysts or can reflect a unilocular/oligocystic serous cystadenomas. Serous (microcystic) cystadenomas can also occur in their polymicrocystic configuration with central scarring or calcification. Unlike the cystic lesions of the kidney in VHL these lesions have no malignant potential. Mucinous cystic lesions do not occur in VHL. In addition to simple cysts and serous cystadenoma a third type of lesion can occur in the pancreas in VHL. This is the presence of neuroendocrine lesions appearing and 8-17% of cases. In this case the enlarged diffusely arterially enhancing lesion in the head the pancreas indeed reflects an additional neuroendocrine tumour. Neuroendocrine lesions in VHL are ubiquitously nonfunctioning, however, have a propensity to malignancy. Despite this predisposition to malignancy they are less likely to metastasize than comparable nonfunctioning neuroendocrine tumours in patients without VHL (10-20% v 60-90%). Criteria have been proosed (Blansfield et al) for projection of metastatic risk in pancreatic neuroendocrine tumour in patients with VHL. These include tumour size greater or equal to 3 cm, the presence of mutation in exon 3 and a tumour doubling time of <500 days. If the patient has none of these criteria the risk of metastatic disease is considered low and radiological surveillance is advised every 2-3 years, if 1 criterion is positive follow-up every 6-12months is advised. If 2 or more criteria are positive surgical management should be considered due to higher risk of future neuroendcrine malignancy.
Dr Vlahos next lecturing commitments are at
European Congress of Radiology (Vienna, March), Society of Thoracic Radiology (Arizona, March), PH Meeting (London, March), Post FRCR London teaching (April), American Roentgen Ray Society (Los Angeles, April), MD Anderson (Summer), Davos IDKD Course (Athens, Sept), RSNA (Chicago, December), National Diagnostic Imaging Symposium (Florida, Dec). Hope to catch you there! The original chest x-ray demonstrates widening of the superior mediastinum, albeit with very sharply defined borders. If there is an appropriate clinical history of a high velocity injury (generally abrupt deceleration from 30mph or greater) then any form of widened or unusual appearance of the mediastinum should be further evaluated by contrast enhanced CT to exclude a vascular injury. Indeed, approximately 10% of vascular injuries occur with a chest radiograph that is normal, therefore, even a normal chest radiograph does not exclude this injury in the right clinical scenario.
In this instance the traumatic history was minor and the radiological interpretation was that this abnormality simply reflected a normal variation of a cervical aortic arch, with both the ascending and descending board crisply visualised. There are no features of rib notching to suggest recurrent lesion associated with a prominent ascending aorta/arch. However, the clinical team was less confident, therefore, insisted on CT. The CT images were performed following injection of contrast from the left arm. The top left image demonstrates the aortic arch is indeed cervical, appearing at the level above the clavicles. On this image the left axillary and brachiocephalic vein can be seen densely opacified with contrast. The second image (top right) demonstrates two abnormalities. Firstly the most anterior venous structure in the thorax, namely the left brachiocephalic vein is absent, hence the ascending aorta is in contact with the sternum. In addition there is a dense contrast opacified structure lying lateral to the trachea, passing posterior to the aorta on this image reflecting the congenitally displaced left brachiocephalic vein passing posterior to the ascending aorta. On the final image this passes anterior to the trachea and joint the right brachiocephalic vein to form a conventional SVC. There is no shunt. This congenital variation is named cervical aortic arch with subaortic brachiocephalic vein. It is a rare benign variation that may become apparent during catheter insertions. It is also important to recognise on non contrast imaging as a potential confusing appearance. The unipacified vessel posterior to the aorta on non contrast imaging can be confused as the right pulmonary artery and in the right paratracheal space for a lymph node. The absence of a brachiocephalic vein at surgery may be confused for a duplicated left SVC which this is not. The presence of a vertically oriented vessels in the left prevascular space has a limited differential. In addition to subaortic brachiocepahlic vein this may include partial or total anomalous pulmonary venous return or left sided superior vena cava. The cause of this particular congenital abnormality is uncertain but likely relates to abnormality development of the middle cardinal vein. You will recall that persistence of the cardinal vein is associated with a left-sided SVC which would descend further down the left side of the cardiac silhouette , via the ligament of Marshall (in the left wall of the left atrium) into the coronary sinus. It has been stated and the incidence of left-sided SVC is less in patients with left brachiocephalic subaortic veins, alluding to different insults of the cardinal vein embryogenesis, however, as this abnormality is so rare such associations are difficult to assess. In and of itself this abnormality is asymptomatic and not usually asssociated with other cardiac disease or significant abnormalities. |
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