CT and MR imaging of the pediatric orbit.

Orbital abnormalities encountered in the pediatric population differ substantially from those found in adult patients. Retinoblastoma, the most serious intraocular tumor, is often difficult to diagnose, but use of computed tomography (CT) (which reveals the characteristic focal calcification) and magnetic resonance (MR) imaging allows this tumor to be differentiated from pseudogliomas, such as Coats disease, and retrolental fibroplasia. CT and MR imaging help in the differentiation of orbital cellulitis from preseptal, lacrimal, and eyelid infectious processes and of orbital pseudotumor from Graves disease. In cases of orbital trauma, CT is excellent for detecting orbital fractures and metallic foreign bodies; MR imaging is better for depicting ocular and optic nerve injuries. Both modalities allow the differentiation of rhabdomyosarcoma from dermoid, cavernous hemangioma, and lymphangioma and provide helpful information for the diagnosis of many other tumors. Since CT and MR imaging have widely expanded the capabilities of orbital imaging, it is more important than ever before for radiologists to understand pediatric orbital disease.     

Pseudotumor of the orbit in pediatrics. Diagnostic imaging

Orbital pseudotumor is an inflammatory lesion with increased orbital mass and a typical rapid onset. It is very uncommon in children. Diagnosis is difficult and there is no uniform procedure. Two patients with different forms of this entity are presented, and their clinical symptoms and CT and ultrasonographic features are discussed. We found the CT and US findings to be important for the differential diagnosis. Therefore, these diagnostic modalities should be applied immediately on the onset of typical clinical symptoms, because the condition can result in ophthalmoplegia and amaurosis if not treated at once.     

Superior blowout fracture of the orbit: the blowup fracture.

We describe a patient who sustained a blowout fracture of the superior orbital roof without an orbital rim fracture. The initial CT study (obtained with 10-mm-thick sections) did not show herniation of the intraorbital fat into the anterior cranial fossa; however, thin (3-mm-thick) direct orbital sections showed a fracture of the midportion of the superomedial orbital roof with displacement of the fracture fragment into the anterior cranial fossa.     

Amyloid tumor of the orbit

Summary A patient with an amyloid tumor of the orbit was studied by computed tomographic scanning. The tumor density was 10 delta units unenhanced and 72 units enhanced.     

Aneurysmal bone cyst of the orbit with unusual angiographic features.

A 14 month old boy with sudden onset of proptosis of the left eye due to an aneurysmal bone cyst of the orbit is reported. Sequential plain films of the orbital region demonstrated changes ranging from subtle loss of bone definition of the orbital margin to the characteristic appearance of an aneurysmal bone cyst twelve months later. Arteriography at the time of the initial evaluation demonstrated prolonged retention of the contrast medium which we believe represents changes secondary to the number of giant cells present in the tumor rather than the relative vascularity of the lesion. While aneurysmal bone cyst of the orbit is extremely rare, it should be included in the differential diagnosis of proptosis in the pediatric age group.     

Giant cell angiofibroma of the orbit

Giant cell angiofibroma (GCA) is a benign pathologic entity that has recently been reported in the literature. Originally described in the orbit, extraorbital sites of disease have also been reported. Herein, we describe the clinical, imaging, and pathologic findings of a case of GCA of the orbit.