Excision margins and elliptical excision — Viva

Q1: Design (2 min)

How do you design an elliptical excision? Why 3:1? What is a dog-ear?

Expected answer: Mark lesion and clinical margin; align fusiform tips with RSTLs; length classically about three times the width to redistribute apical excess and prevent standing-cone (dog-ear) deformity; layered closure shifts tension deep. Small dog-ears may regress by site; large ones need repair.^[4]

Q2: Melanoma margins (3 min)

Recite Breslow-based clinical margins. What if Breslow is unknown?

Expected answer: MIS 0.5–1 cm; ≤1 mm → 1 cm; >1–2 mm → 1–2 cm; >2 mm → 2 cm, following the NCCN margin trials. Without reliable Breslow from adequate biopsy, do not guess a final WLE width — complete microstaging first when feasible.^[1][2]

Q3: NMSC margins (3 min)

Low-risk BCC margin? High-risk BCC pathway? SCC low vs high risk?

Expected answer: Non-infiltrative BCC under 2 cm → 4–5 mm clinical margin (2–3 mm acceptable where reconstructive options are limited, with delayed reconstruction). Low-risk SCC → 4 mm or greater; high-risk SCC → 6 mm or greater, or Mohs following MDT discussion. Tumour depth is of critical importance in identifying high-risk SCC. Where there is a high risk of recurrence, delayed reconstruction or Mohs is used.^[3]

^[2]

Q4: Pathology (2 min)

Clinical vs histologic margin. Limitation of bread-loafing.

Expected answer: Clinical margin is measured on skin; histologic margin is inked edge status on slides. Bread-loafing samples slices only; false reassurance possible between slices. Positive margins usually trigger re-excision/Mohs depending on tumour.

^[1]

Q5: Pitfall (2 min)

Colleague plans a 3 mm ellipse for recurrent nasal infiltrative BCC “to keep scar small.” Response?

Expected answer: Inappropriate. High-risk recurrent infiltrative nasal BCC needs margin-controlled surgery (Mohs) and thoughtful reconstruction. A tight cosmetic ellipse risks deep incomplete clearance and harder salvage.^[3]

References4ShowHide

1. [1]Hanna S, Lo SN, Saw RP. Surgical excision margins in primary cutaneous melanoma: A systematic review and meta-analysis Eur J Surg Oncol, 2021.PMID 33722422
2. [2]Sharib J, Slingluff CL Jr, Beasley GM. Melanoma trials that defined surgical management: Overview of trials that established NCCN margin guidelines J Surg Oncol, 2022.PMID 34897715
3. [3]Newlands C, et al. Non-melanoma skin cancer: United Kingdom National Multidisciplinary Guidelines. J Laryngol Otol, 2016.PMID 27841126
4. [4]Ramsey ML, Walker B, Conrad E, et al. Fusiform Incision. 2026.PMID 29262240