Metanephric Adenoma

Metanephric adenoma is a rare benign renal tumor, accounting for 0.2% of adult renal epithelial tumors. It is a hypovascular solid tumor.

It is a well-demarcated mass that usually shows mild enhancement on CT. It may appear hypointense on T2-weighted images. Differential considerations include papillary renal cell carcinoma and angiomyolipoma with minimal fat.

Reference

• Silverman SG, Mortele KJ, Tuncali K, Jinzaki M, Cibas ES. Hyperattenuating renal masses: etiologies, pathogenesis, and imaging evaluation. Radiographics. 2007 Jul-Aug;27(4):1131-43.
• Hwang SS and Choi YJ. Metanephric adenoma of the kidney: case report. Abdom Imaging. 2004 May-Jun;29(3):309-11.

Reverse 3 Sign

On upper gastrointestinal series, the reverse 3 sign refers to thickening of the duodenal folds with puckering at the site of the ampulla of Vater. This is due to edema, both from duodenal inflammatory changes, or indirect changes involving the pancreatic head. It's classically associated with pancreatic head adenocarcinoma, but can also be seen with acute pancreatitis and duodenal carcinoma.

Reference

Gastrointestinal Radiology: The Requisites (2nd ed). p 85
Clin Imaging. 1991 Oct-Dec;15(4):283-5.

Puestow Procedure

The Puestow procedure is a lateral side-to-side pancreaticojejunostomy that is used for the treatment of chronic pancreatitis. The pancreas is essentially filleted along its long axis from the uncinate process to the tail and connected to a Roux en-Y loop of jejunum.

The pancreaticojejunal anastomosis can usually be seen on CT. The anastomosed loop of bowel may be collapsed and empty, creating a soft tissue bulge arising from the anterior aspect of the pancreatic body and/or tail. This may be mistaken for a tumor when collapsed, or an abscess or pseudocyst when full of fluid and/or gas.

The anastomosed loop of bowel may also contain small amounts of fluid or gas, mimicking an abscess, or be filled with refluxed enteric contrast. In some cases, however, the anastomosis may not be clearly seen.

You may also seen peripancreatic stranding, pancreatic calcifications, or gas or enteric contrast within the pancreatic duct. Some patients who also have a choledochoduodenostomy, choledochojejunostomy, hepaticoduodenostomy, or hepaticojejunostomy before or during the Puestow procedure may also demonstrate pneumobilia.

Reference

Freed et al. Abdomen after a Puestow Procedure: Postoperative CT Appearance, Complications, and Potential Pitfalls. Radiology. 1997; 203(3):790

Traumatic Carotid-Cavernous Fistula

The intraorbital contents should be carefully evaluated in the setting of trauma. A carotid-cavernous fistula can be suggested on non-contrast studies by the enlargement of the superior ophthalmic vein and extraocular muscle(s). The cavernous sinus will also be enlarged, but may not be seen on non-contrast CTs. A CTA can be performed to evaluate the cavernous sinus. CTA of the brain may show dilatation and early enhancemnet. Angiography is considered the gold standard for diagnosis and can be used for treatment.

A potential pitfall is isolated dilatation of the superior ophthalmic vein, which can be seen as a normal variant, in cavernous sinus thrombosis, venous varix, and Graves disease.

Vein of Labbe

The vein of Labbé (also known as the inferior anastomotic vein) is a large superficial vein running from the superficial middle cerebral vein to the transverse sinus. It's found over the mid (60%), posterior (30%), or anterior (10%) aspects of the temporal lobe

The characteristic appearance of thrombosis of the vein of Labbé is hemorrhagic infarction in the lateral aspect of the temporal lobe. Since the drainage territory of the vein of Labbé overlaps the middle cerebral artery territory, occlusion of middle cerebral artery branches may cause a similar appearance.

The two may be differentiating by noting 1) the invariable involvement of the adjacent insular cortex in middle cerebral artery occlusion 2) the propensity of venous occlusions to cause hemorrhagic infarction, and 3) the age of the patient (venous infarctions are more common in young patients).

Reference

• Radiopaedia
• Jones BV. Lobar Hemorrhage from Thrombosis of the Vein of Labbé. Radiology 2003;228:693-696.

Rugger Jersey Spine

The "rugger jersey" spine refers to sclerotic bands along the superior and inferior vertebral body endplates of the thoracolumbar spine, giving it the appearance of a rugby jersey.

The sclerotic areas reflect accumulation of excess osteoid. Although sclerotic-appearing, these areas are actually poorly mineralized.

The finding is virtually diagnostic of osteosclerosis seen with secondary hyperparathyroidism of chronic renal failure.

The rugger jersey spine can be confused with the appearance of other diseases:

• Paget disease: The "picture frame" appearance of Paget disease demonstrates thickening of the cortex of the vertebral body on all sides, not just at the at the superior and inferior endplates.
• osteoporosis: Trabecular thinning causes lucency of the middle vertebral body and relative opacity of the superior and inferior endplates, but you may also see wedging and compression of the vertebral bodies

Reference

Wittenberg A. The rugger jersey spine sign. Radiology. 2004 Feb;230(2):491-2.

Atrial Myxoma

Atrial myxomas are the most common primary tumor of the heart. The majority (>80%) are located in the the left atrium attached to atrial septum, usually at the fossa ovalis.

Clinical Issues

The main clinical concern in embolization, which happens more often with villous tumors (about 1/3 of myxomas are vollous). The myxoma may also become infected, resulting in septic emboli. If the myxoma obstructs the mitral or tricuspid valve, symptoms of valvular stenosis may be seen.

Imaging

Echocardiography is the modality of choice for evaluation. Plain films are almost always normal. 50% of myxomas in the right atrium calcify (rare in left atrium), which may be seen on radiographs.

Differential Diagnosis

• thrombosis
• metastasis
• cardiac lipoma
• lymphoma