JVD 2009 1 Resection Of Mast Cell Tumor If The Lip In A Dog

Question 1

What are the operative goals when resecting a tumor of the oral cavity?

Answer 1

To completely resect the tumor To provide tension free closure To maintain normal occlusion and function of the mouth and oral cavity

Question 2

What percentage of all malignancies in dogs are oral?

Answer 2

5.3%

Question 3

What are the differential diagnoses for this tumor and which diagnosis is most likely?

Answer 3

Mast cell tumor- most likely Differentials: Cutaneous lymphosarcoma Histiocytoma Eosinophilic granuloma Squamous cell carcinoma

Question 4

What treatment options other than surgery were considered ?

Answer 4

Radiation therapy, chemotherapy or a combination of both.

Question 5

What drug was added to the normal premedicant routine and why?

Answer 5

H1 blocker diphenhydramine 3.0mg/kg IM was used to block the effects of histamine release which can occur when mast cell tumors are manipulated during surgery

Question 6

Excisional biopsies of which regional lymph nodes were recommended.

Answer 6

Left parotid, mandibular and medial retropharyngeal

Question 7

What regional blocks were used to provide local anaesthesia?

Answer 7

Bilateral infraorbital blocks

Question 8

What margin was used to resect the tumor on the right dorsal side and the left dorsal side

Answer 8

left 0.5cm right 1.0cm Full thickness through the lip and oral mucosa.

Question 9

What technique is being employed here to resect this tumor?

Answer 9

A bilateral labial advancement flap

Question 10

What substances are released from mast cells when they are activated?

Answer 10

Histamine, heparin, proteases and other inflammatory mediators.

Question 11

What are some of the clinical signs of mast cell disease?

Answer 11

Erythema, pruritus, swelling, ulceration, delayed healing, haemorrhage and anaphylaxis from massive degranulation of mast cells.

Question 12

What percentage of skin and subcutneous tumors are mast cell tumors?

Answer 12

20-25%

Question 13

Why should histopathological evaluation be performed prior to surgery on mast cell tumors?

Answer 13

Aspirates are insufficient to determine histological grade and therefore to determine what test are relevant for determining stage and therefore if surgery alone can be used as treatment.

In low grade tumors amenable to wide excision surgery can be used as the sole therapy.

Question 14

What are the current minimum recommendations for presurgical staging of mast cell tumors?

Answer 14

CBC, serum chemistry panel, FNA of regional lymph nodes and abdominal ultrasound

Question 15

What is the current recommendation for wide surgical excision?

Answer 15

Margins of 3 cm in all planes including the deep margin . The deep marghin must extend at least below the next fascial plane. more recent studies have showed that 2cm lateral margins may be adequate

Question 16

What is the rate of metastasis in well differentiated tumors and undifferentiated tumors?

Answer 16

10% in well differentiated

55-96% in undifferentiated

Question 17

What is the typical survival time of dogs with undifferentiated mast cell tumors when treated with surgery alone?

Answer 17

The typically die of their disease within 1 year as a result of local recurrence or distant metastasis.

Question 18

In

Misdorp W. Incomplete surgery, local immunostimulation, and recurrence of some tumour

types in dogs and cats. Vet Q 1987; 9: 279-286.

what percentage of mast cell tumors with histologically confirmed incomplete margins recurred?

Answer 18

30%