Excision margins and elliptical excision — SAQ

Stem

A 55-year-old outdoor worker has two problems: (1) a biopsy-proven superficial spreading melanoma on the calf with Breslow thickness 1.4 mm, clear deep biopsy margin, and no ulceration; (2) a separate 8 mm well-defined primary nodular BCC on the upper back. He wants both treated with “simple cuts.”

Questions

a) Draw or describe the design principles of an elliptical excision (orientation, length:width, layered closure). (2 marks)

^[5]b) State the recommended clinical surgical margin for his melanoma and justify it. (3 marks)

^[4]c) State an appropriate clinical margin approach for his low-risk back BCC and when you would choose Mohs instead. (3 marks)

d) Explain why a pathology report of “margins clear” after standard excision is not identical to Mohs clearance. (2 marks)

^{[1] [3]}

Model answer

a) (2 marks) — Align a fusiform ellipse with relaxed skin tension lines; length classically about 3 times width to reduce dog-ears;^[5] measure clinical margin from visible edge; incise to planned deep plane; close in layers (deep dermal then epidermal) to offload the surface scar.

^[2]b) (3 marks) — Breslow 1.4 mm falls in the >1.0–2.0 mm band → clinical margin 1–2 cm (commonly examined AAD-aligned teaching), after adequate microstaging. Include appropriate depth of subcutaneous tissue; counsel scar length and follow-up.

c) (3 marks) — Well-defined primary BCC is a classic 4–5 mm clinical margin standard-excision candidate if low-risk overall. Choose Mohs (or wider/specialist surgery, with delayed reconstruction where recurrence risk is high) for high-risk features: H-zone face, recurrence, aggressive histology, poorly defined borders, large size, or critical tissue conservation needs.^[6]

^[1]d) (2 marks) — Standard vertical bread-loaf sectioning samples representative slices only, not 100% of the peripheral and deep margin. Mohs examines the entire margin in staged en face sections. Clinical millimetres and histologic clearance are related but not identical concepts.

References6ShowHide

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]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
4. [4]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
5. [5]Hudson-Peacock MJ, Lawrence CM. Comparison of wound closure by means of dog ear repair and elliptical excision J Am Acad Dermatol, 1995.PMID 7896954
6. [6]Newlands C, et al. Non-melanoma skin cancer: United Kingdom National Multidisciplinary Guidelines. J Laryngol Otol, 2016.PMID 27841126