Merkel cell

Question 1

Work up

Answer 1

“Wide local excision of ext with 1-2 cm margin, SLN

Path: Small round blue cells. Positive for NSE and CK56. Sometimes positive for chromogranin and synaptophysin”

Question 2

Dosing

Answer 2

“primary site: unresectable 60-66 Gy, neg margins 50-56, microscopic 56-60, +margins 60-66 Gy

Nodes: SLNBneg - can omit nodes, otherwise 46-50 for no SLNB, 50-56 for N+

Can observe if size <1 cm with good margins after WLE and no LVSI or immunosurpression”

Question 3

Fields

Answer 3

“5 cm margins around the primary site. Smaller margins are accetptable in head and neck, at least 2 cm

If treating nodes, include in between intransit lymphatics (meaning don’t leave an area getting no dose in between primary and nodes)”

Question 4

Radiation Start?

Answer 4

“Begin radiation ASAP for Merkel cell

Teeth eval after RT”

Question 5

Follow up

Answer 5

PE with complete skin exam and LN exam q 3-6 months x 2 years, then q 6-12 mo thereafter

Question 6

Outcomes

Answer 6

“3yr DSS 75%, 3yr OS 70-80% for localized, 50-60% if nodal mets, 30% if distant meets

LC 85% with RT, from 15% without%
DM 15%”