Mast Cell Tumor and Transitional Cell Carcinoma Flashcards
(32 cards)
Name the most commonly diagnosed skin tumour in the dog
Mast cell tumour
List some other sites that mast cell tumours form
Subcutaneous tissue
Conjunctiva
Oral mucosa
GIT
Describe the behaviour of mast cell tumours
Variable - some benign, some aggressive
Describe the predispositions for mast cell tumours
Unknown aetiology (?Genetic predisposition)
Any age and no sex predilection
Breed predispositions e.g. Boxer, Boston terrier.
Describe the clinical presentation of mast cell tumours
- Cutaneous mass of variable external appearance.
- Anywhere in the body
- Usually solitary
- Local effects e.g., erythema, oedema, pruritus, haemorrhage (Darier’s sign)
- Systemic signs e.g., vomiting, melaena and rarely collapse
How do mast cell tumours appear microscopically
Intracytoplasmic granules containing histamine, heparin and proteases → degranulation
How are mast cell tumours diagnosed?
- FNA of the mass:
- Usually diagnostic (92-96%)
- Round cells
- Characteristic purple granules - Diff Quick usually fine - Occasionally need special stains e.g. toluidine blue
- For some poorly differentiated biopsy +/- IHC required
How can you stage mast cell tumours
Tests to assess the patient for metastatic disease
1. Haematology/ Biochemistry/Urine analysis:
- Usually unremarkable
- Rule out any other problems and suitability for subsequent therapies
2. FNA or biopsy of local LN:
- Always FNA regional LN regardless of size
- Interpretation can be difficult - chemotaxis post surgery vs metastasis
3. Abdominal ultrasound
- Assess liver, spleen, LNs
- Higher risk or caudal body
4. Thoracic radiography - Lung metastasis uncommon but to evaluate sternal LN
List the clinical factors that influence the prognosis of mast cell tumours
- Location e.g. Nail bed, oral, muzzle, prepuce, perineum, mucocutaneous junction.
- Breed: Sharpei (high grade) vs boxer (low grade)
- Appearance
- Systemic illness
- Recurrence
- ?Clinical staging (i.e. presence of metastatic disease)
What is the most important prognostic factor for mast cell tumours?
Histological grade from a biopsy
Can predict recurrence and metastasis
Describe a grade 1 tumour using the Patnaik grading system
Grade I / well differentiated tumours:
- Benign behaviour (<10% metastasise)
- Low recurrence rates
- Unlikely to cause death (up to 7-12%)
Describe a grade II tumour using the Patnaik grading system
Grade II/ intermediate tumours:
- Variably metastatic (5-22% metastasise)
- Cause of death in 17-56% of patients
- Nodal metastases associated with poorer prognosis in some studies but not in all
Describe a grade III tumour using the Patnaik grading system
Grade III/ poorly differentiated tumours
- Highly metastatic (>80%)
- Likely to be cause of death
Describe the Kiupel grading system
Just 2 groups; low grade and high grade
Median survival time
- Less than 4 months for high-grade MCT
- More than 2 years for low-grade MCTs
Describe the surgical margins needed for mast cell tumours
3cm margins & 1 fascial plane (ideally but many not be achievable anatomically)
1-2cm lateral margins may be adequate for grade I and II tumours
Describe the use of radiotherapy for mast cell tumours
- Postoperative - incompletely excised (grade I/II 1-2yr DFI 81-95% and 80% alive at 5yrs)
- Local nodal metastasis (DFI 40mo)
- Gross disease - degranulation
Describe the use of chemotherapy for mast cell tumours
- High grade and/or confirmed metastasis
- Neoadjunctively prior to surgery e.g. cases with a larger tumour or where full excision doesn’t seem possible – will shrink the tumour
- Cases of residual microscopic disease
Which agents are commonly used for chemotherapy of mast cell tumours?
- Vinblastine/prednisolone: vinblastine weekly for 4 weeks then fortnightly for 4 further treatments
- Lomustine: PO q 3 weeks or alternating with vinblastine q 2 weeks
Describe the use of tyrosine kinase inhibitors for mast cell tumours
Toceranib/Masitinib
- Non-cytotoxic thyrosine kinase inhibitors.
- Licensed for unresectable, metastatic or high grade MCT
- Kit mutation status can determine response to treatment (70% vs 30% RR) -> tumours with a kit mutation have a poorer prognosis
- Very expensive
Name the two forms of feline mast cell tumours
Cutaneous
Visceral
Describe cutaneous feline mast cell tumours
- Second most common cutaneous tumour in the cat (20%)
- Cutaneous raised hairless masses.
- Easily diagnosed by cytology and rarely metastatic. Multiple tumours.
- Surgical excision is usually curative (even marginal).
Describe the visceral forms of feline mast cell tumours
- Splenic: Most common differential for splenic disease. Clinical signs of systemic disease.
- Staging is recommended.
- Splenectomy is the treatment of choice even if involvement of other organs (MST 12-19 months).
- Unclear role of chemotherapy. - Intestinal: Third most common intestinal tumour.
- Signs of GI and systemic disease and palpable abdominal mass.
- Metastasis are common.
- Poor prognosis (?chemotherapy/TKI).
In which part of the bladder do transitional cell carcinomas form?
Bladder trigone but urethra and prostate in males.
Where do transitional cell carcinomas most commonly metastasise to?
Medial iliac lymph nodes and other organs (liver, spleen, bones etc)
