Oncology - Mast Cell + Others Flashcards
What is a mast cell?
A bone marrow derived cell that lives in the periphery involved in allergic reactions
True or False: MCTs are the most common skin tumor and malignant skin tumor.
True
Where are MCTs most commonly located?
50% trunk and perineum
40% extremities
10% head and neck
When is the mean age of diagnosis for MCTs?
8-9 years
What are the clinical signs associated with MCTs due to?
the release of histamine and heparin
What is Darier’s sign?
erythema and wheal formation at a MCT
What clinical signs are associated with MCTs?
Bleeding when mass aspirated/excised GI ulceration Fever Peripheral edema Hypotensive events/collapse Coagulation abnormalities
What are the prognostic factors for MCTs?
Histologic grade, clinical stage, anatomic location, cell proliferation rate, growth rate, recurrence, systemic signs, breed, tumor size, and C-KIT mutation
If MCTs are going to metastasize, where do they metastasize most commonly?
Regional lymph nodes
Systemic - distant lymph nodes, spleen, liver
Pulmonary (very rare)
- Dogs with gross/visible MCTs are at increased risk of this systemic side effect due to the histamine present in their mast cells:
a. Gastric ulceration
b. epistaxis
c. pulmonary metastasis
d. uveitis
a. gastric ulceration
What is the most common way to diagnose MCTs?
Fine-needle aspirate cytology +/-incisional biopsy
How do you do a fine-needle aspirate cytology?
Use a 22G hypodermic needle and insert it into the mass for a minimum amount of 10 insertions. Then stain with Diff-Quik
What cytological findings are consistent with a MCT?
Small to medium sized round cells
Abundant, small, uniform cytoplasmic granules that stain purplish-red
What method should you NOT use to diagnose MCT?
excisional biopsy because it is very important to get margins on your first surgery
What does the Patnaik system grade based on?
Cytoplasmic boundaries, nuclear shape/size, mitotic index, and granules
Define grade I of the Patnaik system.
Well differentiated (10-20%)
Define grade II of the Patnaik system.
Intermediate differentiated (60-80%)
Define grade III of the Patnaik system.
Poorly differentiate/anaplastic with infiltrative growth (10%)
What did the 2-tier grading scheme determine the survival time for a high grade MCT was?
less than 4 months
What did the 2-tier grading scheme determine the survival time for a low grade MCT was?
greater than 2 years
When should you consult a pathologist in MCT cases?
The histology does not = biologic behavior - rapidly growing, large tumor, and LN metastasis
Why is palpation alone of the LN not recommended for MCT staging?
Because of the low sensitivity and specificity - normal LN size does not mean there is no metastasis
How are 70-80% of MCTs managed?
With surgery alone
How do you downstage large MCTs prior to surgery?
Chemotherapy, radiation therapy, and prednisone
What surgical margins are recommended for cutaneous MCTs?
Lateral margins - 2 cm or maximal diameter of MCT, whichever is GREATER
Deep margins - fascial
What surgical margins are recommended for subcutaneous MCTs?
Lateral margins - 2cm or maximal diameter of MCT, whichever is LESS
Deep margins - fascial layer
What LN is most commonly excised in MCT patients?
the regional lymph node because they are often involved - recommendation is to excise it when possible
True or False: Incomplete surgical excision followed by observation alone is correlated with a significant decrease in survival times in dogs and recurrence.
True
In cases of incomplete surgical excision, what should you do?
Wide surgical excision or radiation therapy
Consider a MCT prognostic panel
When is chemotherapy not indicated if there is incomplete surgical excision?
If it is a low grade MCT
What are some prognostic panels for MCT?
Proliferation indicies, KIT staining patterns, and C-KIT mutation status
When should you do KIT mutation testing?
In cases of a high/grade III/ high MI (metastatic index)
What should you do if you get a positive KIT mutation result?
Chemotherapy + palladia
What should you do if you get a negative KIT mutation result?
Chemotherapy alone vs. chemo and palladia
When should you run a full MCT panel?
Incomplete resection
Biologic behavior does not fit histopathology
Hot anatomic sites (muzzles, mucocutaneous)
Low owner risk tolerance
What are the indications for chemotherapy in MCT patients?
High-grade MCT, metastatic MCT, non-resectable MCT, and visceral MCT
- Chemotherapy is not indicated for which group of dogs with mast cell tumors?
a. High-grade MCTs
b. Metastatic MCTs
c. Completely excised low-grade MCTs
d. Non-resectable MCTs
e. Visceral MCTs
c. Completely excised low-grade MCTs
What is the MOA of palladia?
To shut of the KIT, VEGFR, and PDGFR receptors
True or False: Palladia is FDA-approved for use in cats with MCT
False - dogs with MCT
What does the Tigilanol tiglate intratumoral injection do?
PKC activator
What are the supportive therapy considerations for MCT?
H1 blocker, H2 blocker, (or) Proton-pump inhibitor (PPI)
Antiemetic
Appetite stimulant
What H1 blockers can you use for MCT patients?
Diphenhydramine and cetirizine
What H2 blockers can you use for MCT patients?
Famotidine and ranitidine
What PPIs can you use for MCT patients?
Omeprazole
What antiemetics can you use for MCT patients?
Maropitant and ondansetron
What appetite stimulants can you use for MCT patients?
Capromorelin
- Mutation of which gene/receptor is associated with a more guarded prognosis and worse clinical outcome for dogs with mast cell tumors?
a. BRAF
b. C-KIT
c. VEGF
d. PDGF
b. C-KIT
What is the general recommendation for feline mast cell neoplasias?
surgical excision
What is the median age for cutaneous SCC diagnosis?
10-11 years
What anatomic locations have a predilection for cutaneous SCC?
Head/nasal planum and ventral abdomen
What is the recommended treatment for cutaneous SCC?
Surgical when feasible
+/- radiation therapy
+/- chemotherapy
What is the most common digital tumor?
digital SCC
How is digital SCC treated?
Primarily surgical +/- chemotherapy
What is the prognosis for digital SCC?
1-year survival (50-83%)
2-year survival (18-62%)
Melanomas involving ________ often behave in a benign manner.
haired skin
How is cutaneous/dermal melanoma treated?
Surgical excision is often curative - histopathological evaluation is important
What is the second most common digital tumor?
digital malignant melanoma
True or False: Metastasis is more common in digital SCC patients than in digital melanoma patients.
False - it is more common in digital melanoma patients
What is the recommended treatment for digital malignant melanoma?
Primarily surgical +/- immunotherapy
What is the prognosis for digital malignant melanoma?
1 year survival - 42-57%
2 year survival - 13-36%
