Today's Veterinary Practice

NOV-DEC 2018

Today's Veterinary Practice provides comprehensive information to keep every small animal practitioner up to date on companion animal medicine and surgery as well as practice building and management.

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PEER REVIEWED 40 NOVEMBER/DECEMBER 2018 of a mass. Sometimes diagnosis can be based on histopathologic appearance of enucleated globes. Diagnosis and Prognosis Canine uveal melanomas tend to grow in a distinctive nodular fashion, but diagnosis may still be challenging. Clients may note a color change in the eye as the first sign of a problem, or the mass may go unnoticed until it causes uveitis and/or secondary glaucoma. Melanocytic tumors are diagnosed clinically, based on location in the iris, nodular appearance, and typical dark pigmentation, although some can be nonpigmented. Large masses can cause dyscoria, anterior displacement of the iris, or lens subluxation. For patients with dramatic uveitis or hyphema that prevents direct examination, use of ocular ultrasonography may help you determine the diagnosis and anatomic location. Melanocytic tumors have a low metastatic potential (4% to 6%), and the prognosis for the patient's overall health is good, but secondary complications may necessitate enucleation. 1,5,7-9 Ciliary body tumors often go undiagnosed until they have caused significant uveitis and secondary glaucoma. Because of their location posterior to the iris, they often remain unseen until they have grown quite large. Occasionally, they can be seen as a tan or pink mass behind the lens or extending through the pupil. In most cases, however, they are detected by ocular ultrasonography or even histopathology after globe enucleation because of intractable glaucoma. Fortunately, although about 15% of these tumors are malignant, their metastatic potential is low and the prognosis for overall health is good. 5 Ocular ultrasonography is a valuable, noninvasive imaging tool and can generally be performed by an ophthalmologist or radiologist to help make a diagnosis and further recommendations. It is particularly useful for patients with opacities in the clear ocular media that prevent direct examination, and it can generally be performed without sedation. Even for patients in which the mass can be directly observed, ultrasonography can help you determine the origin of the mass as well as enable its measurement. Most practitioners use B-mode ultrasonography for image capture, although A-mode can be useful for taking measurements and is used in human ophthalmology for evaluating the internal structure of some masses. 10 The accuracy of ultrasonography for identification of intraocular masses is good, but occasionally intraocular blood clots can mimic masses 10 ( FIGURE 3 ). For avoiding misdiagnosis of blood clots as tumors, standardized imaging protocols performed by an experienced operator can be helpful; for some animals, serial ultrasonography can also be beneficial. For obtaining images of the best possible quality, appropriately sized probes for ocular imaging are needed. For some patients, computed tomography or magnetic resonance imaging is helpful. These modalities can be used to detect bony involvement, extra-ocular soft tissue extension, or local invasion from an intraocular tumor. They can also provide information for surgical planning and help determine whether further treatment with chemotherapy or radiation might be needed. Treatment Treatment of any intraocular neoplasia in the dog is FIGURE 3. Ultrasonography image of a globe from a patient with hyphema, partial anterior lens luxation, and secondary glaucoma; image obtained by use of B-mode ultrasonography. Ultrasonography revealed retinal detachment (arrow) and possible ciliary body mass (asterisk). Because of secondary complications, this eye was enucleated. Histopathologic examination revealed retinal detachment and a blood clot in the posterior chamber. Courtesy of Dr. Ellen Belknap (3) Ciliary body tumors often go undiagnosed until they have caused significant uveitis and secondary glaucoma. *

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