What is the most appropriate management for a 2cm basal cell carcinoma (BCC) on the cheek?

Management of 2cm Basal Cell Carcinoma on the Cheek

For a 2cm BCC on the cheek, Mohs micrographic surgery is the most appropriate management, as facial location constitutes high-risk disease regardless of size, and this tumor exceeds the low-risk size threshold. 1, 2

Why This Lesion is High-Risk

• Location alone makes this high-risk: According to NCCN guidelines, any BCC in the H-zone (central face, including cheeks) constitutes high risk independent of size 1
• Size exceeds low-risk threshold: Low-risk primary BCC is defined as well-defined lesions <2cm, making this 2cm lesion at the upper boundary or potentially beyond low-risk classification 2
• Facial BCCs have higher recurrence rates: Even with standard excision and histologically negative margins, facial BCCs showed 12.2% recurrence at 10 years, with 56% of recurrences identified beyond 5 years 1

Treatment Algorithm for This Case

First-Line: Mohs Micrographic Surgery

• MMS achieves superior cure rates: 5-year recurrence rates of 1% for primary BCC versus higher rates with standard excision 1
• Provides complete margin control: En face horizontal sectioning allows examination of 100% of peripheral and deep margins, critical for facial locations where subclinical extension is unpredictable 1
• Maximizes tissue preservation: Essential on the cheek where cosmetic and functional outcomes matter 1

Second-Line: Standard Excision (If MMS Unavailable)

• Requires wider margins than 4mm: For high-risk tumors, 5-10mm margins are suggested, though even these may be insufficient without complete margin control 1, 3
• Must include complete histologic margin assessment: Standard "bread loaf" sectioning with verification of negative margins before closure 1
• Avoid tissue rearrangement until margins confirmed clear: Residual tumor can be spread during complex closures 4

Why Neither Answer Option is Ideal

Option A (4mm margin) is inadequate:

• 4mm margins are for LOW-RISK tumors only: The AAD guidelines explicitly state "for low-risk primary BCC, surgical excision with 4-mm clinical margins" 1, 2
• This lesion does not meet low-risk criteria: Facial location and 2cm size disqualify it from low-risk classification 1, 2
• Historical data shows 4mm clears <95% of 2cm tumors: The classic 1987 study establishing 4mm margins specifically stated this was for tumors <2cm 5

Option B (2mm margin) is grossly inadequate:

• 2mm margins fail even for small facial BCCs: A 2005 study of small (<1cm) well-demarcated facial BCCs showed 24% positive margin rate with 2mm margins 6
• This tumor is 2-4 times larger than those studies: Research supporting narrow margins examined lesions averaging 0.6cm, not 2cm 6, 7
• Positive margins carry 26.8% recurrence risk: Versus 5.9% with negative margins 1

Critical Pitfalls to Avoid

• Do not treat facial BCCs as low-risk: Location automatically elevates risk regardless of clinical appearance 1, 2
• Do not use curettage and electrodesiccation: Facial lesions treated with C&E show 47% residual tumor rates and 19-27% recurrence 1, 2
• Do not assume well-defined borders mean limited subclinical extension: BCCs characteristically show asymmetrical subclinical extension beyond visible margins 1
• Do not perform inadequate initial excision: Re-excision increases morbidity, scarring, and patient anxiety while potentially spreading tumor cells 1, 4

If Forced to Choose Between the Two Options

If MMS is absolutely unavailable and you must choose between 2mm or 4mm margins, choose 4mm (Option A) with the understanding that this remains suboptimal and requires:

• Complete circumferential margin assessment with permanent sections 1, 4
• Delayed closure until margins confirmed negative 4
• Close long-term surveillance given inadequate margins for high-risk disease 1, 3
• Patient counseling about higher recurrence risk than MMS 1

The 2mm option (B) should never be selected for a 2cm facial BCC, as it virtually guarantees positive margins and treatment failure 6, 8