Grade II Spinal Cord Ependymomas

Ependymomas of the spinal cord originate from the ependymal walls. They have been classified by the World Health Organization into grades I, II, and III. Grade I tumors include myxopapillary ependymomas and subependymomas. Grade II tumors are just called ependymomas and can be further divided as cellular, papillary, clear cell, or tanycytic. Grade III tumors are called anaplastic ependymomas, tend to occur in the brain, and are rare in the spine.

Grade II spinal cord ependymomas (simply called ependymomas) tend to be located somewhat centrally in the cervical spinal cord in association with large satellite cysts.

MRI is the imaging modality of choice. Ependymomas are isointense to slightly hypointense to the spinal cord on T1-weighted images and may have areas of hyperintensity due to hemorrhage. Satellite cysts are T1-hypointense. T2-weighted images reveal a hyperintense mass with or without intramural cysts. Polar (rostral or caudal) cysts and a syrinx may also be seen in the adjacent spinal cord. Hemorrhage may also be seen, sometimes presenting as a "cap sign" (hemosiderin deposits due to chronic hemorrhage at the rostral or caudal margins). Post-contrast images reveal avid and homogeneous enhancement.

Differential considerations for an intramedullary cyst with one or more enhancing nodules includes:

• Ependymoma: Well-circumscribed mass with hemorrhage. More common in the cervical spine.
• Myxopapillary ependymoma:
• Pilocytic astrocytoma: Most common primary spinal cord neoplasm in children. Can be eccentric with indistinct margins. Hemorrhage is uncommon.
• Hemangioblastoma: Look for a hemangioblastoma in the brain, cysts in the pancreas, and cystic or solid lesions in the kidneys to make the diagnosis of von Hippel-Lindau disease.

References

• Balériaux DL. Spinal cord tumors. Eur Radiol. 1999;9(7):1252-8.
• Armstrong TS, Vera-Bolanos E, Gilbert MR. Clinical course of adult patients with ependymoma: Results of the Adult Ependymoma Outcomes Project. Cancer. 2011 Apr 28.

Pleural Masses

Multiple

• Pleural metastases: Case shown above (Ewing sarcoma)
• Asbestos related pleural disease: Look for calcifications.
• Malignant mesothelioma: Diffuse nodular pleural thickening, thicker at lung bases, with a small hemithorax and pleural effusion. Grows along fissures.
• Invasive thymoma: Pleural metastases rare, but well-described.
• Lymphoma: Look for other enlarged nodes.
• Splenosis: Left-sided pleural thickening in a patient with history of distant trauma and an absent spleen.

Solitary

• Pleural metastases:
• Solitary fibrous tumor of the pleura: Hypervascular mobile mass displacing rather than invading adjacent structures. No chest wall involvement. Calcifications are more common in malignant lesions, but malignant and benign tumors are indistinguishable on imaging.
• Lipoma: Like solitary fibrous tumors of the pleura, pleural lipmas may also be pedunculated and mobile.
• Malignant mesothelioma:

Cemento-Osseous Dysplasia

Cemento-osseous dysplasias are a group of benign fibro-osseous lesions that arise from periodontal ligament tissues in the tooth-bearing regions of the mandible and maxilla. Cemento-osseous dysplasias can be classified as periapical, focal, and florid based on location and extent (see below).

Early in the course of the disease radiographs and CT reveal a predominantly lucent lesion with multiple closely apposed or confluent, round or ovoid cystic areas. There is a narrow zone of transition with adjacent normal bone. As the disease progresses, the lesions become progressively more opaque internally. There is usually no extension into adjacent bone or cortical expansion. Infection in overlying teeth (spontaneous or post biopsy) may spread across the lesion and evolving into osteomyelitis with sequestration.

Small, discrete lesions may mimic apical periodontitis, while larger lesions can look similar to ossifying fibromas.

Cemento-osseous dysplasia can be classified as:

• Periapical: Also known as cementoma, periapical cementoma, periapical cemental dysplasia, and periapical fibrous dysplasia. Predominantly involves the apical areas of mandibular incisors.
• Focal: Essentially the same entity as periapical cemento-osseous dysplasia, but predominantly involving the tooth-bearing areas of the posterior jaws, particularly in sites of former extraction. Some have proposed that both periapical and focal cemento-osseous dysplasia be known as focal cemento-osseous dysplasia.
• Florid (shown above): A more extensive version of focal cemento-osseous dysplasia that involves two or more quadrants of the jaw. Most cases have bilateral mandibular molar/premolar involvement with or without maxillary involvement. Florid cemento-osseous dysplasia is usually asymptomatic, with pain being the most common symptom in symptomatic patients.

Special thanks to Dr. Carla Ross for the case.

References

• Eversole R, Su L, ElMofty S. Benign fibro-osseous lesions of the craniofacial complex. A review. Head Neck Pathol. 2008 Sep;2(3):177-202.
• Scholl RJ, Kellett HM, Neumann DP, Lurie AG. Cysts and cystic lesions of the mandible: clinical and radiologic-histopathologic review. Radiographics. 1999 Sep-Oct;19(5):1107-24.

Pineal Region Masses

• Pineal cyst (shown above): Most common pineal lesion.
• Pineal tumor: Pineoblastoma (children), germinoma (young adults), pineocytoma (older people).
• Extrapineal tumor: Meningioma, tectal glioma.
• Arachnoid cyst: Located in the quadrigeminal plate cistern.
• Infection: Neurocysticercosis.
• Congenital: Lipoma.
• Dermoid/epidermoid cyst:
• Vein of galen malformation:

J-Shaped Sella

The J-shaped sella, seen on the lateral view of the skull, is caused by flattening of the tuberculum sellae, forming the stem of the J. The normal dorsum sellae forms the loop of the J. The extension of the anterior aspect of the sella is distinguished from the true pituitary fossa by the tuberculum sellae.

Differential considerations include:

• Normal variant: In 5% of normal children. Normalizes later in life.
• Hypothyroidism:
• Slowly growing parasellar tumor: Optic glioma (e.g., in neurofibromatosis type 1).
• Mucopolysaccharidoses: Classically described in Hurler syndrome, but can be seen in the other mucopolysaccharidoses. The case above is from a patient with Hunter syndrome.
• Mild arrested hydrocephalus:
• Hajdu-Cheney syndrome: Rare disorder of bone metabolism. The diagnosis is made by finding acroosteolysis with any three of the following: Wormian bones, open skull sutures, platybasia, micrognathia, mid-facial flattening, premature loss of teeth, coarse hair, and short stature.

References

• Merle P, Georget AM, Goumy P, Jarlot D. Primary empty sella turcica in children. Report of two familial cases. Pediatr Radiol. 1979 Oct;8(4):209-12.
• Wren MW. Significance of the so-called J-shaped sella in the diagnosis of intracranial aneurysm. Br J Ophthalmol. 1969 May;53(5):307-9.

Gallstones Misbehaving

• Gallstone ileus: A gallstone that erodes through a biliary-enteric fistula and gets imapcted in the terminal ileum, causing obstruction. Occurs in 15% of patients with a biliary-enteric fistula.
• Mirizzi syndrome: Gallstone impacted in the cystic duct results in extrinsic compression and obstruction of the extrahepatic bile duct. The cystic duct is usually oriented parallel to the extrahepatic bile duct. CT, ultrasound, or MRI shows a calculus at the junction of the cystic duct and extrahepatic bile duct in conjunction with a dilated bile duct proximal to and a normal-caliber duct distal to the calculus.
• Bouveret syndrome: Biliary-enteric fistula allows a gallstone to enter the duodenum. Gastric outlet obstruction may occur due to impaction of the gallstone in the distal stomach or proximal duodenum. Occurs most commonly in elderly women.
• Dropped calculi: Gallstone spillage is fairly common during laparoscopic cholecystectomy (up to 30%). Abscess formation is relatively rare (< 3%), with the calculus serving as the nidus for infection days to years after cholecystectomy. Patients will usually develop recurrent abscesses until the calculus is removed (drainage and antibiotics by themselves are not effective). Calculi may be found anywhere in the peritoneal or even pleural cavity. Dropped calculi may mimic peritoneal metastases and metastatic ovarian cancer. Invasion through the abdominal wall or across tissue planes with fibrosis and draining sinuses can be seen with actinomycosis, and may mimic a malignant process.

References

• Brennan GB, Rosenberg RD, Arora S. Bouveret syndrome. Radiographics. 2004 Jul-Aug;24(4):1171-5.
• Gayer G, Petrovitch I, Jeffrey RB. Foreign Objects Encountered in the Abdominal Cavity at CT. Radiographics. 2011 Mar-Apr;31(2):409-28.
• Turner MA, Fulcher AS. The cystic duct: normal anatomy and disease processes. Radiographics. 2001 Jan-Feb;21(1):3-22;
• Vyas JM, Kasmar A, Chang HR, Holden J, Hohmann E. Abdominal abscesses due to actinomycosis after laparoscopic cholecystectomy: case reports and review. Clin Infect Dis. 2007 Jan 15;44(2):e1-4.

The Jatene Procedure: Basics

The Jatene, or arterial switch, procedure corrects D-transposition of the great vessels. Patients usually first receive palliative treatment with prostaglandin E1 and balloon atrial septostomy (Rashkind procedure). The Jatene procedure is then performed in the first month of life

The Jatene procedure involves switching the main pulmonary artery (MPA) and the aorta (Ao) and relocating the ostia of the coronary arteries (RCA and LCA) to the new aorta. The Lecompte procedure is also performed, whereby the main pulmonary artery bifurcation is placed anterior to the ascending aorta. Axial images show the aorta posterior to the main pulmonary artery and between the right and the left pulmonary arteries (RPA and LPA, respectively). Dense contrast is seen in the left brachiocephalic vein (LBCV) on the coronal curved reformatted image.

Complications to watch for include:

• Left ventricular impairment: Early.
• Coronary artery issues: Early. Stenosis or occlusion.
• Supravalvular pulmonary artery stenosis: Most frequent midterm complication. Most commonly occurs at the site of the anastomosis between the former aorta, any interposed graft (used to lengthen the main pulmonary artery), and the main pulmonary artery. Our patient had supravalvular stenosis and underwent pericardial patch augmentation of the main pulmonary artery (not clearly visible on CT).
• Right or left pulmonary artery stenosis: Tend to occur after a Lecompte procedure, possibly due to stretching of these arteries after extensive dissection. Our patient had narrowing of the right pulmonary artery, which was subsequently stented.

References

• Beek FJ, Beekman RP, Dillon EH, Mali WP, Meiners LC, Kramer PP, Meyboom EJ. MRI of the pulmonary artery after arterial switch operation for transposition of the great arteries. Pediatr Radiol. 1993;23(5):335-40.
• Gutberlet M, Boeckel T, Hosten N, Vogel M, Kühne T, Oellinger H, Ehrenstein T, Venz S, Hetzer R, Bein G, Felix R. Arterial switch procedure for D-transposition of the great arteries: quantitative midterm evaluation of hemodynamic changes with cine MR imaging and phase-shift velocity mapping-initial experience. Radiology. 2000 Feb;214(2):467-75.
• Kersting-Sommerhoff BA, Seelos KC, Hardy C, Kondo C, Higgins SS, Higgins CB. Evaluation of surgical procedures for cyanotic congenital heart disease by using MR imaging. AJR Am J Roentgenol. 1990 Aug;155(2):259-66.
• Martins P, Castela E. Transposition of the great arteries. Orphanet J Rare Dis. 2008 Oct 13;3:27.