melanosis or melanoma in cats

January 18, 2016 8:09 AM

Please share your experiences dealing with your cat's diagnosis of ocular (eye) melanosis or melanoma. Melanosis is the spreading of eye freckles on the iris, whereas melanoma is a tumor on the iris. These separate conditions can appear similar. Please share how your vet has diagnosed and treated either condition.

thank you.

posted by Jason and Laszlo to Pets & Animals (3 answers total)

My cat Mel's eye has been completely brown for over ten years now, and he has never received treatment. He was "diagnosed" by my mom who is a retired vet and named him "Mel for melanoma". He has only actually visited a vet's office once, when he had an infection we could not treat at home, and none of the vets there (also family members) commented on the melanoma.
posted by acidic at 9:03 AM on January 18, 2016

Melanosis can be differentiated from melanoma by clinical ophthalmic examination.

Signs suggestive of melanoma rather than benign melanosis include: rapid increase in size, diffuse pigmentation of the iris, thickening of the pigmented area, difference in iris size, changes in pupil movement, infection of the iris, and increased intraocular pressure (glaucoma).

A true differential diagnosis is obtained by histopathology (looking at slices of tissue under the microscope) after enucleation (removal). It is not possible to biopsy the iris without significant damage to the eyeball.

Regular ophthalmic examination including an intraocular pressure (IOP) every 6 months is recommended to monitor melanosis. Melanoma likes to spread to the liver, lungs, bones, and lymph nodes, and can have already done so when neoplastic change is detected in the eye. But most cases of iris melanosis do not undergo malignant change to melanoma.

If you suspect melanosis or melanoma, go see your vet so they can perform a full eye exam, or refer you to someone who will.
posted by Seppaku at 9:18 AM on January 18, 2016

I don't have experience with this, but I wanted to say that I've found the r/AskVet sub on reddit to be a great resource for these sorts of questions.
posted by schroedingersgirl at 9:44 AM on January 18, 2016