Ocular oncology

Bulbus Destruction by Choroidal Melanocytoma in a Dog: A 3-Year History

A 3-year-old male Slovak Hound with retinal detachment was presented. The causative intraocular mass was detected by ultrasonography, and the course of the disease was monitored over a 3-year period. Enucleation was performed due to secondary glaucoma. A benign choroidal melanocytoma was diagnosed by histopathology. To our knowledge, this is the first report that describes the disease over such a long period of time. The mild course of the disease questions enucleation of eyes with no or minor symptoms. Conventional treatment may be a suitable alternative to surgery for dogs with high anesthesia risks.

Current Therapeutics and Future Perspectives to Ocular Melanocytic Neoplasms in Dogs and Cats

Neoplasms of melanocytic origin are diseases relevant to dogs and cats' ophthalmic oncology due to their incidence, potential visual loss, and consequent decrease in life quality and expectancy. Despite its non-specific clinical presentation, melanocytic neoplasms can be histologically distinguished in melanocytomas, which present benign characteristics, and malignant melanomas. The diagnosis often occurs in advanced cases, limiting the therapeutic options. Surgery, cryotherapy, radiotherapy, photodynamic therapy (PDT), and laser are currently available therapeutic strategies. As no clinical guidelines are available, the treatment choice is primarily based on the clinician's preference, proficiency, and the owner's financial constraints. While surgery is curative in benign lesions, ocular melanomas present a variable response to treatments, besides the potential of tumour recurrences or metastatic disease. This review presents the currently available therapies for ocular melanocytic neoplasms in dogs and cats, describing the therapeutic, indications, and limitations. Additionally, new therapeutics being developed are presented and discussed, as they can improve the current treatment options.

Choroidal neuroendocrine neoplasia in a dog

OBJECTIVE

To report onset and progression of clinical signs of a neuroendocrine neoplasm (NEN) presumed metastatic to the choroid in a dog.

ANIMALS STUDIED

A 7.5-year-old female spayed German shepherd dog mix referred for advanced imaging and evaluation of a subretinal mass in the right eye.

PROCEDURES

Procedures performed included general physical and ophthalmic examinations; ocular, orbital, and abdominal ultrasonography; thoracic radiographs; cranial magnetic resonance imaging; serologic testing for infectious agents; analysis of hematologic as well as serum and urine biochemical parameters; echocardiography; electrocardiography; cytologic assessment of lymph nodes; and histopathology and immunohistochemistry of the enucleated globe.

RESULTS

Examination and imaging identified a pigmented mass within and expanding the superior choroid. Following enucleation, a choroidal NEN with tumor emboli in scleral blood vessels was diagnosed by histopathologic assessment and confirmed by immunohistochemical labelling. Despite extensive and repeated diagnostic testing over many months, a putative primary site was not identified until 19 months after the initial ocular signs were noted. At that time, a heart-base mass and congestive heart failure were highly suggestive of a chemodectoma.

CONCLUSION

This comprehensive report of a NEN presumed metastatic to the choroid in a dog suggests that ocular disease can be a very early and solitary sign of NEN in the dog.

Retrobulbar embryonal tumor with multilayered rosettes in a golden retriever dog

Although rare, embryonal tumors (previously called primitive neuroectodermal tumors) should be considered in the differential diagnosis of retrobulbar tumors in dogs regardless of the age of the patient, and ancillary tests are required for definitive diagnosis.

The investigation of histopathology and locations of excised eyelid masses in dogs

Background

Eyelid masses are the most common ocular diseases in dogs. However, there are no studies specifically investigating the location of eyelid masses.

Methods

118 dogs with 119 eyelid masses were included. Medical records and pathology reports were retrospectively reviewed at National Taiwan University veterinary hospital and Vision Eyecare Centre for Animals between 2012 and 2017.

Results

Mean age of dogs was 9.4±2.5 years. Female spayed dogs had significantly higher prevalence of eyelid mass than female intact dogs (p<0.01). Prevalence of upper eyelid mass was significantly higher than lower eyelid mass (p<0.01). The upper lateral eyelid was the significantly more common location compared with the upper medial eyelid. Mean mass volume was 258.2±661.0 mm³. The most common eyelid mass type was meibomian epithelioma (34.5%), followed by meibomian adenoma (29.4%) and meibomian hyperplasia (18.5%). Non-tumours comprised 25.2%, benign tumours comprised 67.2% and malignant tumours comprised 7.6% of all eyelid masses. Malignant tumours were significantly larger than benign lesions (p<0.01). All dogs underwent surgical excision without any complications.

Conclusion

The majority of eyelid masses were benign. Surgical intervention can prevent further ocular irritation and provide good prognosis.

Feline ocular post-traumatic sarcomas: Current understanding, treatment and monitoring

PRACTICAL RELEVANCE

Ocular tumors in cats are seen uncommonly in general practice. Feline ocular post-traumatic sarcomas (FOPTS) represent a very aggressive type of ocular cancer that occurs in cats with a prior history of trauma or severe intraocular disease. Treatment options are limited and early recognition is imperative for close monitoring of disease progression and prompt enucleation.

CLINICAL CHALLENGES

There is often a delay between the initiating ocular trauma and tumor formation, with an average latency of approximately 6-7 years. Therefore, many cases may not be presented with a documented history of a traumatic incident, especially if the event occurred prior to adoption. While a histologic diagnosis is easy to obtain with enucleation, the aggressive and locally invasive behavior of FOPTS may prevent complete surgical resection.

GLOBAL IMPORTANCE

Cats are the most popular pet in the USA and Western Europe. As there is no breed predisposition for this particular cancer, and males are only slightly over-represented compared with females, a relatively large population of companion animals is at potential risk of developing FOPTS.

AUDIENCE

While uncommon, the understanding and recognition of this tumor type by general practitioners is important for the feline patient. This allows for close monitoring of cats known to have undergone serious ocular trauma, and prompt referral or early enucleation, as well as client education.

PATIENT GROUP

The typical patient is a middle-aged to older cat with a history of mechanical trauma to the eye, past intraocular surgery or chronic uveitis.

EVIDENCE BASE

Historically, there has been limited clinical evidence upon which to determine the optimal treatment for FOPTS, beyond enucleation of the affected eye. Recommendations are generally based on limited case reports and clinical experience of the practitioner.

Outcome of secondary intention healing of full thickness lower eyelid defects in dogs

OBJECTIVES

To assess healing of the canine lower eyelid without anatomical reconstruction.

MATERIALS AND METHODS

Retrospective case series of three client-owned dogs with lower eyelid defects. These dogs that underwent debridement of lower eyelid wounds that were left to heal by secondary intention were assessed for anatomical, functional and aesthetic outcomes.

RESULTS

Two of the cases had previously undergone tumour resection with a lip-to-lid reconstruction and, following flap failure, developed a full thickness defect. The third dog presented with a traumatic laceration. Each dog lost approximately 70 to 90% of the lower eyelid margin. Two received topical antimicrobial eye drops after debridement, while the third dog required no further treatment. Follow-up periods of 3 years, 15 months and 4 months were available. All owners were satisfied with the cosmetic outcome and provided pictures. One owner reported epiphora but no other ophthalmic complications occurred.

CLINICAL SIGNIFICANCE

The result of this small case series supports the notion that not all lower eyelid injuries or tumour resections require anatomical reconstruction. Selected cases can be left to heal by secondary intention with minimal post-operative complications.

Comparative Aspects of Canine Melanoma

Melanomas are malignant neoplasms originating from melanocytes. They occur in most animal species, but the dog is considered the best animal model for the disease. Melanomas in dogs are most frequently found in the buccal cavity, but the skin, eyes, and digits are other common locations for these neoplasms. The aim of this review is to report etiological, epidemiological, pathological, and molecular aspects of melanomas in dogs. Furthermore, the particular biological behaviors of these tumors in the different body locations are shown. Insights into the therapeutic approaches are described. Surgery, chemotherapy, radiotherapy, immunotherapy, and the outcomes after these treatments are presented. New therapeutic perspectives are also depicted. All efforts are geared toward better characterization and control of malignant melanomas in dogs, for the benefit of these companion animals, and also in an attempt to benefit the treatment of human melanomas.

Management of eyelid neoplasms in the dog and cat

Eyelid neoplasms are common in the older dog and typically benign. Eyelid neoplasms in the cat are less common and more often malignant. Resection of eyelid masses may be curative; however, restoration of the eyelid structure after mass excision is essential for maintaining long-term ocular surface health. Surgical techniques and instrumentation for eyelid surgery are reviewed. Indications, benefits. and limitations of sharp excision, cryotherapy, and laser excision and ablation are discussed. Neoplasia of the third eyelid is also discussed.

Suspected uveal metastasis of a nail bed melanoma in a dog

A 13-year-old Golden Retriever was referred for evaluation of generalized corneal edema, dyscoria, and suspected glaucoma affecting the right eye. The dog exhibited no signs of systemic illness, but had a history of a melanoma of the nail bed of the first digit of the right hind limb, excised 1 year previously. Ophthalmologic examination revealed diffuse corneal edema, mild anterior uveitis, glaucoma and a mass within the right iris. Enucleation was performed and histopathologic evaluation of the globe revealed the iris to be infiltrated with an anaplastic melanoma, suspected to represent a metastasis of the original nail bed tumor.

Use of chemical ablation with trichloroacetic acid to treat eyelid apocrine hidrocystomas in a cat

CASE DESCRIPTION

A 7-year-old Persian cat was evaluated for recurrence of multiple cystic periocular masses. A number of cyst-like lesions had been resected from the left eyelids 18 months earlier, with lesions recurring within 6 months after surgery. The cat had blepharospasm and signs of discomfort following rupture of the largest cyst the day prior to examination. Previous histologic examination of the cysts had revealed apocrine hidrocystomas.

CLINICAL FINDINGS

Multiple pigmented nodules were seen around the skin of the upper and lower left eyelids. The nodules were brownish to black, round, soft, and fluid-filled. Signs of pain were not evident during palpation of the nodules.

TREATMENT AND OUTCOME

The largest cyst on the upper eyelid was removed by means of a V-shaped full-thickness excision. Histologic and immunohistochemical examination of the excised tissue confirmed the diagnosis of apocrine hidrocystoma. The remaining periocular cysts were surgically debrided and then treated topically with 20% trichloroacetic acid. All lesions healed rapidly without any signs of discomfort. During a recheck examination 12 months later, the upper and lower left eyelids appeared morphologically normal, and there was no evidence of recurrence.

CLINICAL RELEVANCE

Findings suggested that chemical ablation with trichloroacetic acid may be a useful treatment for apocrine hidrocystomas in cats.

Standardised B-scan and A-scan echographic evaluation of spontaneous anterior uveal melanomas in the dog

In humans, A-scan echographic characteristics of choroidal and ciliary body malignant melanomas permit the prediction of histopathological findings in >95% of cases. The aim of this study was to determine the echographic characteristics, in A-mode and B-mode, of 16 spontaneous anterior uveal melanomas in the dog using a 10 MHz sector transducer. The acoustic hallmark of the tumours was their low to medium reflectivity, internal vascularity and hard consistency. All had an irregular shape, with no acoustic shadowing and the regular lesional spikes. In our experience, the most important sonographic differential diagnoses are ciliary body adenocarcinoma and chronic inflammatory lesions. We believe that standardised A-scan echography can be used in the evaluation and diagnosis of a very high percentage of anterior uveal melanomas.