Labrador with changed appearance

Signalment:

9-year-old male neutered Labrador Retriever

Chief complaint:

For the last three months he had not been eating well at home and would not eat dry food so the clients had changed him to tinned food. Two weeks ago the clients noticed the change in him that led to this consultation.

1

What did you find question, based on the photograph, when you examined this dog? Large mass on the maxilla causing facial deformity Swelling of the temporal muscles on the left side Muscle wasting over the entire head and face Muscle wasting of the temporal muscles on the right side Nothing: the dog looked normal Please select an option Incorrect. Look more closely at the photograph. Incorrect. Look more closely at the photograph. Incorrect. Look more closely at the photograph. Correct! Incorrect. Look more closely at the photograph.

2

What cranial nerve innervates this muscle? Facial Trigeminal Abducens Hypoglossal Oculomotor Please select an option Incorrect. Review anatomy and choose again. Correct. Incorrect. Review anatomy and choose again. Incorrect. Review anatomy and choose again. Incorrect. Review anatomy and choose again.

3

You examine the dog further and can feel a large mass located at the caudal part of the ramus of the mandible. When you open his mouth you see a large tumour. What is the most common oral tumour seen in the dog? Osteosarcoma Squamous cell carcinoma Malignant melanoma Amelioblastoma Fibrosarcoma Please select an option Incorrect. Review oral tumours and choose again. Incorrect. Review oral tumours and choose again. Correct. Incorrect. Review oral tumours and choose again. Incorrect. Review oral tumours and choose again.

4

Based on your knowledge of oral tumours which of the above carries the best prognosis (i) and which carries the worst prognosis (ii)? (i) Amelioblastoma, (ii) fibrosarcoma (i) Squamous cell carcinoma, (ii) malignant melanoma (i) Fibrosarcoma, (ii) osteosarcoma (i) Malignant melanoma, (ii) amelioblastoma (i) Amelioblastoma, (ii) malignant melanoma Please select an option Incorrect. Review oral tumours and choose again. Incorrect. Review oral tumours and choose again. Incorrect. Review oral tumours and choose again. Incorrect. Review oral tumours and choose again. Correct

5

What do you recommend to your client? Do nothing. This tumour is large and must have invaded the temporal muscles. Advise an incisional biopsy and computed tomography (CT) scan to determine the extent of the tumour. Excise what you can from the inside of the mouth. Recommend palliative care and send him home on non-steroidal anti-inflammatory drugs (NSAIDs). That irrespective of a biopsy the prognosis is poor and you would have to remove his dog’s jaw. Please select an option Incorrect. You have made a judgement without attempting to evaluate your patient. Understandably your client is not satisfied and goes for a second opinion. Correct Incorrect. That would not benefit your patient and would literally just make a mess. Your client decides to get a second opinion. Incorrect. Your client wants to know if anything further can be done for his dog and therefore seeks a second opinion. Incorrect. You need a better idea of the extent of the tumour and exactly what it is before deciding on options.

Histopathology report

Stratified squamous epithelium covering the tissue is ulcerated. The epithelial tissue is proliferative and contiguous in places with a mass present below. The underlying collagen is infiltrated by a solid mass of proliferating squamous epithelial tissue. The epithelial tissue occurs as masses, trabeculae or nests with minimal stromal tissue. The epithelial cells are variable in size; they have large nuclei with prominent nucleoli; mitotic figures are frequent.

6

Your client went ahead with the CT scan and biopsy and now wants to know what you found. The biopsy report is available for you to examine but unfortunately the diagnosis is missing so you will have to interpret it for your client. Review the Histopathology report and make your diagnosis. Osteosarcoma Squamous cell carcinoma Malignant melanoma Amelioblastoma Fibrosarcoma Please select an option Incorrect. Making a wrong diagnosis affects the treatment plan and prognosis. Correct. Incorrect. Making a wrong diagnosis affects the treatment plan and prognosis. Incorrect. Making a wrong diagnosis affects the treatment plan and prognosis. Incorrect. Making a wrong diagnosis affects the treatment plan and prognosis.

7

You next review the CT scan. What are your findings based on the scan? A this is a large tumour but should be easy to remove as the bone is not affected. There is significant lysis of the mandible so surgery is not an option. The cancer has spread to the nerves so surgery would not be possible. There is significant bony lysis and the tumour is extensive so a hemimandibulectomy would be necessary to debulk this tumour surgically. The tumour has infiltrated the temporal muscles so you don’t know how it could be removed. Please select an option Incorrect. Your client is not convinced and gets a second opinion. Incorrect. Your client is not convinced and gets a second opinion. Incorrect. Your client is not convinced and gets a second opinion. Correct. Incorrect. Your client is not convinced and gets a second opinion.

8

What is the treatment of choice for oral squamous cell carcinoma in the dog? Removal of tumour with underlying bone (mandibulectomy/maxillectomy) with adequate margins. Carboplatin chemotherapy Radiation Palliative therapy with NSAIDs Photodynamic therapy Please select an option Correct. Incorrect. Your client is unhappy with your knowledge of his dog’s condition. You can review the chapter on oral tumours in North and Banks, Small Animal Oncology. Incorrect. Your client is unhappy with your knowledge of his dog’s condition. You can review the chapter on oral tumours in North and Banks, Small Animal Oncology. Incorrect. Your client is unhappy with your knowledge of his dog’s condition. You can review the chapter on oral tumours in North and Banks, Small Animal Oncology. Incorrect. Your client is unhappy with your knowledge of his dog’s condition. You can review the chapter on oral tumours in North and Banks, Small Animal Oncology.

9

The problem in this case is that the tumour is extremely large and located caudally so even with a hemimandibulectomy medial margins would not be achieved and adjuvant radiation would be required. Your client is concerned about such a large surgery and wants to know if there are any alternative options. Can you suggest another option? Debulking surgery Palliative Cyclooxygenase-2 (COX-2) inhibitors Radiation Please select an option Incorrect. This has already been discussed. Incorrect. This would be unlikely to have a major impact on this tumour, especially when a superior treatment option is available. Incorrect. This would be unlikely to have a major impact on this tumour, especially when a superior treatment option is available. Correct. Choose again.

10

It was decided to go ahead with a course of neoadjuvant radiotherapy with the goal of shrinking the tumour to reduce surgical dose. Before starting treatment however it is important to complete staging. What is required to stage this patient fully? Thoracic radiographs or CT scan Lymph node aspirate/excisional biopsy Both thoracic radiographs/CT scan and lymph node aspirate/excisional biopsy No staging is required because this tumour does not metastasize. Please select an option Incorrect. An additional diagnostic procedure is required in this case. Choose again. Incorrect. An additional diagnostic procedure is required in this case. Choose again. Correct. A CT scan was performed and a lymph node biopsy was negative. Incorrect. Your client wants the very best for his dog and so decides to take him to another veterinary surgeon. Choose again. Choose again.

11

You now review the contrast-enhanced thoracic CT scan. Based on the image, what do you tell your client? The CT scan is normal and there are no visible secondaries in the lungs. There are metastatic nodules throughout the lungs and nothing further can be done. There are metastatic nodules in the lungs but they will grow slowly so treatment for the oral tumour should go ahead anyway. There are metastatic nodules in the lungs but they will be treated with chemotherapy. The scan shows evidence of pulmonary fibrosis so the patient has a second serious medical problem. Please select an option Correct. Incorrect. Unfortunately your client takes your advice and euthanizes his dog. Incorrect. Your client is concerned that he would be putting the animal through a lot but wouldn’t have very long because of the metastasis and so decides on euthanasia. Incorrect. Your client is concerned that he would be putting the animal through a lot but wouldn’t have very long because of the metastasis and so decides on euthanasia. Incorrect. Your client is concerned that he would be putting the animal through a lot but wouldn’t have very long because of the metastasis and so decides on euthanasia.

12

Why would an excisional lymph node biopsy of the submandibular lymph node be superior to a fine-needle aspirate? A. Squamous cell carcinoma often causes local inflammation resulting in enlarged lymph nodes; it is important to rule out reactive versus neoplastic. B. It is unlikely that the lymph node would be positive so it doesn’t really make any difference. C. A biopsy is always more accurate because early metastatic cells can be missed on cytology. D. Both A and C are correct E. Neither would be appropriate because the sentinel node in this location would be the retropharyngeal node. Please select an option Incorrect. Choose again. Incorrect. Incorrect. Choose again. Correct. Incorrect. Choose again.

13

Radiotherapy went well and the tumour shrank, permitting a reduced surgical dose. The patient underwent a caudal mandibulectomy. What is the most common acute side-effect of irradiating the oral cavity? Vomiting Tooth decay Mucositis Fibrosis Thinning of cortical bone Please select an option Incorrect. Choose again. Incorrect. Choose again. Correct Incorrect. Choose again. Incorrect. Choose again.

14	What is the most common delayed effect of irradiating the oral cavity? Bone necrosis Gingival recession Tooth loss Fibrosis of the tongue Skin necrosis Please select an option Incorrect. Choose again. Correct Incorrect. Choose again. Incorrect. Choose again. Incorrect. Choose again.

15

In view of the successful elimination of the primary, what do you consider the patient’s long-term prognosis to be? Excellent - he should be cured. Very good - the risk of local recurrence or metastatic spread is low. Good - he may develop metastatic spread, but not for years. Fair - this was a large tumour that had been present for months before detection so recurrence or metastatic spread is still a possibility. Poor - he would be unlikely to live more than 6 months. Please select an option Incorrect. This is what we would hope but local recurrence or metastatic spread is still a possibility. Incorrect. This is what we would hope but local recurrence or metastatic spread is still a possibility. Incorrect. This is what we would hope but local recurrence or metastatic spread is still a possibility. Correct. Incorrect. He should have a better prospect than 6 months.

16

Your client had a cat that had exactly the same problem and he wants to know if she could have had the same treatment. What do you tell your client about oral squamous cell carcinoma in the cat? The cat could have had neoadjuvant radiation followed by a caudal mandibulectomy with the same outcome. We never perform mandibulectomies on cats because they will not tolerate them. Oral squamous cell carcinoma of the mandible of the cat is very sensitive to radiation so radiation is the sole treatment. Oral squamous cell carcinoma of the cat does not respond well to radiation and the results have been poor with conventional protocols. Cats do not get mandibular squamous cell carcinoma; it is always sublingual. Please select an option Incorrect. Review oral squamous cell carcinoma in the cat. Incorrect. Review oral squamous cell carcinoma in the cat. Incorrect. Review oral squamous cell carcinoma in the cat. Correct. Incorrect. Review oral squamous cell carcinoma in the cat.

17

Currently, what is the treatment of choice for cats with oral squamous cell carcinoma? Early detection while surgery is still an option Mitoxantrone chemotherapy Approved NSAID Prednisolone Cisplatin chemotherapy Please select an option Correct. Incorrect. Q15&17 are general knowledge questions and do not relate to your ability to manage your patient. Incorrect. Q15&17 are general knowledge questions and do not relate to your ability to manage your patient. Incorrect. Q15&17 are general knowledge questions and do not relate to your ability to manage your patient. Incorrect. Q15&17 are general knowledge questions and do not relate to your ability to manage your patient.

This resource was adapted from North and Banks, Small Animal Oncology provided by Elsevier Health Sciences as part of the PublishOER Project.