PRESENTING SIGNS

Most cases present because the eye has become red or the owner has noticed a change in appearance. Some blepharospasm and ocular discharge might be present but this is not consistent, especially early in the course of the disease. It is more common to encounter unilateral cases, associated with primary intraocular neoplasia, but bilateral cases, normally associated with metastatic disease, do occur. These latter patients are more likely to present with a uveitis rather than just change of appearance, and the patient might be systemically unwell. Such cases are discussed more in the section on uveitis. Thus, in most dogs, there are no other clinical symptoms which the owner has noticed. Sometimes the owner has not been aware of any problem at all and the lesion is identified by the veterinary surgeon during a consultation for something else. Affected dogs are typically 8–10 years and older.

CASE HISTORY

In most cases there is no previous history of ocular disease, or relevant systemic disease.

CLINICAL EXAMINATION

Since most cases of intraocular neoplasia will be primary rather than secondary it is likely that the general clinical examination will be normal. Obviously if both eyes are affected or the patient is unwell, then metastatic disease is more likely. However, the majority of cases will be unilateral. As such, the abnormal eye can be compared to the normal one during examination which is helpful.

The affected eye might be blind but usually vision is present. Thus a menace response is likely to be normal. Some conjunctival hyperaemia and episcleral congestion might be present but not always. Normally a discoloured lesion will be present. This can be on or in the iris, or behind it poking thorough the pupil. Its colour can vary from dark brown to pale pink and various shades in between (Figure 37.1). The pupil is frequently distorted (dyscoria) but pupillary light reflexes remain. Mild uveitis, with aqueous flare and episcleral congestion, can be present and occasionally the patient is not presented until the eye is painful and enlarged through secondary glaucoma.

Figure 37.1 Ciliary body mass in an elderly Labrador cross. The non-pigmented mass can be seen at 1–3 o’clock behind the pupil. Apart from some dyscoria due to the mass, plus age-related iris atrophy and nuclear sclerosis, the eye is otherwise unremarkable.

If the neoplasm is based in the iris, then the discolouration will be visible within the iris, and can be raised above it (Figure 37.2). Thus looking at the eye from the side can be useful to determine if the lesion protrudes out from the plane of the iris. Ciliary body-based masses are more difficult to see initially; however, by dilating the pupil the lesion should be more easily visualized through the pupil, especially when looking tangentially across the eye. Vitreal haze is often present with ciliary body neoplasms. Fundus neoplasia is rare but occasionally chor-oidal extension of uveal melanomas does occur.

Figure 37.2 Uveal melanoma in a Labrador. The pigment is close to the iris base and slightly raised above the plane of the iris.

The most commonly encountered uveal tumour in dogs is the iris melanoma/melanocytoma, with ciliary body adenoma/adenocarcinoma the next most frequent. However, many tumour types can occur – haemangiosarcoma, medulloepithelioma, primary lymphoma and so on, and although the clinical examination can suggest the tumour type, it is only on histological examination or cytology that this can be confirmed.

DIFFERENTIAL DIAGNOSES

• Non-neoplastic proliferations (e.g. iris freckles and pigment dispersal syndrome)

• Iris darkening following uveitis (diffuse hyperpigmentation)

• Intraocular extension from extraocular mass (e.g. limbal melanoma; see Case example 56.1)

• Perforating injury with iris prolapse

• Uveal cyst (Figure 37.3)

Figure 37.3 Iris cyst in a Labrador. The pupil has been dilated. The free floating cyst can be seen to be hollow and is not attached to the iris.

CASE WORK-UP

If an ocular mass is suspected a thorough clinical examination is required to try to establish whether this is primary or secondary. Thus if there are no changes in the fellow eye, nor on general examination, it is appropriate to assume the lesion is primary – especially if it presents as a mass rather than a diffuse uveitis.

Gonioscopy can be useful to determine whether extension into the drainage angle has occurred (which could indicate an increased risk of metastasis as tumour cells escape from the eye into the general circulation). Ocular ultrasonography can be considered but this might not provide further information about the lesion (although it can differentiate a solid mass from a cyst). Chest and abdominal radiography and/or ultrasonography should be undertaken if there is any suspicion of metastatic spread – for example, in advanced cases where there is not only a visible mass but also associated uveitis and secondary glaucoma.

Fine needle aspirates of draining lymph nodes can also be performed should metastatic disease be suspected. However, since many cases of ocular neoplasia in dogs are primary, and metastasis is uncommon, extensive work-up is not usually required unless there is an unusual aspect to the presentation.

Stay updated, free articles. Join our Telegram channel

Join