Orbital Tumors Workup

Updated: Sep 04, 2019
  • Author: Michael Mercandetti, MD, MBA, FACS; Chief Editor: Hampton Roy, Sr, MD  more...
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Workup

Laboratory Studies

Laboratory testing should be directed by the clinician's suspicion level of the presumed etiology of the lesion. For example, lymphatic tumors require blood cell counts, imaging studies, and bone marrow evaluation. Often, the diagnosis is made following orbital biopsy or after removal of the lesion. In these scenarios, laboratory studies are predicated by the histopathologic findings.

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Imaging Studies

The structural complexities of the orbit and its content present an imaging challenge. Strides in radiologic modalities have allowed the clinician to obtain detailed and logistic information about orbital tumors. [13]

Before the advent of computerized tomography (CT) scans, roentgenography was the imaging modality most commonly used to evaluate suspected orbital masses. Since roentgenography allows for only a 1-dimensional view and poorly defines soft tissue structures, CT scan has become the mainstay of orbital imaging.

CT scan, first used in the 1970s, is the product of tissue density calculations. X-rays with different vectors are emitted, penetrating through target tissues with resulting radioabsorbencies. These differences in radioabsorbencies are assigned value-specific gray shades to create the 2-dimensional image. CT scan can produce detailed axial and coronal views of soft tissue and bony structures. Image windows from 1-3 mm in thickness allow for detailed evaluation of orbital masses. Contrast-enhanced images may be obtained and can help identify inflammatory processes, vascular tumors, and engorged vessels. Calcified lesions are discernible without the addition of contrast. See the image below.

Axial CT scan revealing lateral orbital neoplasm. Axial CT scan revealing lateral orbital neoplasm.

Magnetic resonance imaging (MRI) excites protons by applying a radio frequency with a strong magnetic field. Hydrogen nuclei emit signal intensities that are assigned specific gray tones to create an anatomical reproduction. Three-dimensional views can be gained, directly, in any anatomical plane offering excellent spatial resolution of orbital masses and soft-tissue enhancement. MRI may provide excellent soft-tissue resolution, but CT scan is superior for gleaning details about orbital bony structures.

Coronal MRI showing left orbital cavernous hemangi Coronal MRI showing left orbital cavernous hemangioma.

Ocular ultrasonography can be used to visualize anterior and middle orbital lesions. Sound waves of 5-15 MHz breech orbital tissues that reflect echogenic energy captured by an oscilloscope. A-scan ultrasonography allows for a 1-dimensional description of echoes, while B-scan ultrasonography provides a 2-dimensional image. C-scan ultrasonography affords coronal views, and D-scan ultrasonography creates 3-dimensional orbital views. With the advent of CT scan, C and D ultrasonography remain unpopular. Doppler ultrasonography may be used to evaluate orbital vasculature and blood flow.

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Diagnostic Procedures

Fine needle aspiration biopsy (FNAB) is a technique used for diagnosing orbital lesions. This outpatient procedure allows for retrieval of a cytological specimen through a well-controlled and minimally invasive surgical technique. In experienced surgical hands, FNAB can differentiate benign from malignant lesions with an accuracy of 95%. FNAB coupled with clinical and radiological finding can lead to a proper diagnosis in 80% of cases. Disadvantages include poor cellular yield, cytopathologic and not a histological diagnosis, difficulty in interpreting the specimen, and inadequate cellular yields requiring another biopsy procedure. Potential complications include retrobulbar hemorrhage, globe perforation, ptosis, extraocular motility dysfunction, and inadvertent entry intracranially. Patients with cystic lesions should not undergo FNAB.

Open biopsy of an orbital tumor is the common method of obtaining tissue from the orbital lesion. It also may be necessary if FNAB is not able to obtain adequate tissue for pathological assessment. An advantage of the open biopsy is the establishment of a histological diagnosis because enough of a specimen usually is obtained. Disadvantages include the associated morbidity and costs associated with this procedure.

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Other Tests

Genetic analysis of tumors has aided in tumor identification. [14]

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Staging

The TNM guideline advocated by the American Joint Committee on Cancer (AJCC) [15] is used to stage cancers of the orbit. The "T" relates to tumor characteristics and size, "N" denotes status of the lymph nodes in the regional area, and "M" stands for metastases. These components result in an overall "stage" that ranges from 0 to IV. [16, 17]

The two most employed stages are a clinic stage and a pathologic stage, the latter being based on the tissue itself.

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