Mast Cell Tumors

Question 1

What markers are MCT positive for?

Answer 1

vimentin, tryptase, and CD117 (KIT) positive

Question 1

Treatment of choice for MCT localized to the skin in areas amenable to wide excision

Answer 1

surgery

Question 2

Surgical margins for MCT

Answer 2

• Historically, surgical excision to include a 3-cm margin
• Metric approach uses a prescribed metric distance, with lateral margins of 1 cm and 2 cm for low- and intermediate-grade MCTs
• Proportional approach uses lateral margins proportional to the maximum dimension of the MCT.
• For both approaches, deep margins include removal of one uninvolved fascial plane in continuity with the tumor.

Question 3

Treatment options of MCT if
primary closure is not possible regardless of the width of the lateral
margins

Answer 3

• Wide excision +/-chemotherapy depending on histologic grading
• Marginal excision followed by adjuvant therapy

Question 4

Two-year control rates for stage 0 tumors of low- or intermediate-grade
MCTs treated with surgery followed by RT

Answer 4

85% to 95%

Question 5

Treatment options after curative excision surgery is unsuccessful and histologic margins are incomplete

Answer 5

• Scar revision surgery
• RT

Question 6

% of regrowth in MCTs with histologically confirmed incomplete margins

Answer 6

10-30%