By Dr Ananya Mandal, MD
Once a patient present with symptoms of eye disease like blurring or loss or vision or change in the appearance of the eye, the ophthalmologist examines the eye carefully for eye cancers.
Diagnosis of intraocular melanoma
Tests commonly used to diagnose intraocular melanoma include (1, 2, 3) –
- Ophthalmoscopy – An ophthalmoscope is a small portable instrument that can be used to look into the inside cavity of the eye through the lens.
- Ultrasound scan – This device is a small one that uses sound waves to look at the various structures within the eye. The probe is rubbed around the eye.
It emits sound waves which send back echoes that can be converted into a radiological picture by a computer. The black, white and grey plate can reveal the internal structure of the eye.
- Fundus photography – This method takes a color picture of the back of the eye or retina. This can show the tumor before and after treatment in some cases. The camera takes the picture after the pupil is fully dilated or expanded using special eye drops.
- Biopsy of the cancer or tumor – Sometimes a small sample of tissue is aspirated with a needle or removed under a microscope.
Ocular melanomas often do not often require a biopsy to confirm diagnosis. Once biopsy is done the cells visible under the microscope may show spindle cells (long tapered cells) (Grade 1), epitheloid cells (oval cells) (Grade 3) or mixed cells (Grade 2). (4)
- CT scan or computerised axial tomography – This is a standard technique that takes three-dimensional picture of the inside of eye. Sometimes a contrast dye may be injected before the scan. This also highlights blood vessels on the scan and helps identify the tumor and its location.
- Fluorescein angiography – This technique uses a dye called flourescein that is given intravenously over the arm. The dye travels in the blood through the blood vessels of the eye. A special camera takes the picture of the blood vessels of the eye, choroid and iris with the dye highlighting the blood vessels.
- An MRI (magnetic resonance imaging) scan – This gives a more detailed picture of the inner structures of the eye.
- A PET scan or Positron Emission tomography scan. This is also an imaging technique that looks at the inner structures of the eye.
- Sometimes in individuals with inherited forms of melanomas biopsy samples may be subjected to chromosomal or genetic tests for diagnosis.
- Routine blood tests – Melanomas of the eye may spread to other organs – commonly the liver. Routine blood tests for general health, liver and kidney function tests are important to exclude spreads.
- Imaging studies like CT scan, PET scan or MRI of the abdomen, bones or other parts of the body is often indicated to exclude spread of the cancer to other parts of the body.
Diagnosis of intraocular lymphomas
Tests commonly used to diagnose intraocular lymphomas include (3) –
- Imaging studies – Ultrasound scans, CT scans and MRI scans are used to diagnose the cancers. They show the size, location and shape of the tumors and also show any enlarged or affected lymph nodes around the eyes. These lymph nodes may carry cancer cells.
- Biopsy – Usually a fine needle is used to aspirate some vitreous fluid from within the eye. The sample is examined under the microscope for lymphoma cancer cells.
- Lumbar puncture or spinal tap – Since eye lymphomas may be an extension of central nervous system lymphomas, a spinal tap to examine the Cerebrospinal fluid may be needed. The CSF bathes the brain and the spine and thus may offer clues to affliction of the spine or brain with lymphoma.
- Bone marrow examination may be done to exclude spread or other locations of the lymphoma.
Staging of eye cancer
Once the cancer is detected it needs to be staged. Staging helps doctors decide the extent of spread of cancer, its outcome and possible treatment strategy.
Diagnostic tests are used to determine the stage of the eye cancer.
The most common staging method is using the TNM grades. Here T stands for Tumor; N for nodes or lymph node involvement; and M for metastasis or spread of the tumor.
For eye cancers Tumor size for uveal melanomas affecting iris is different from that affecting choroidal and ciliary bodies.
TX stands for undetected and T0 stands for no tumor. T1 tumor of iris is when it is confined to the iris, T2 is when it has spread to the ciliary body or choroid, T3 when it has reached sclera and T4 when it has reached outside the eyeball.
Similarly NX means unevaluated lymph node spread, N0 means no node involvement and N1 means regional node involvement.
Spread, if present, is denoted by M1 and if absent by M0.
Based on a combination of these features the cancer is staged into Stages I (e.g. T1, N0, M0), II (e.g. T2, N0, M0), III (e.g. T3, N0, M0) or IV (any T, N1, M0; or, any T, any N, M1). There are further sub stages. A recurrent cancer that has returned after successful elimination by therapy is also reclassified. (4)
Edited by April Cashin-Garbutt, BA Hons (Cantab)
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Last Updated: May 30, 2012