Flashcards in Oncology - Mast Cell + Others Deck (60)
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.
Where are MCTs most commonly located?
50% trunk and perineum
10% head and neck
When is the mean age of diagnosis for MCTs?
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
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
c. pulmonary metastasis
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.
In cases of incomplete surgical excision, what should you do?
Wide surgical excision or radiation therapy
Consider a MCT prognostic panel