Patient Presentation
A 45-year-old woman presents with a rapidly growing, irregularly shaped mole on her upper back. Over the past few months it has changed in color and size and has occasionally bled.
On examination the lesion is asymmetric with irregular borders, multiple colors, and a diameter greater than 6 mm. There are no palpable axillary or cervical lymph nodes described.
Her past medical history is unremarkable and there is no family history of skin cancer. She is otherwise healthy and asks you what should be done about the lesion.
What You'll Be Asked — and What a Strong Resident Discusses
-
How would you initially evaluate this pigmented lesion, and what makes it concerning?
Expected answer
A focused history (risk factors: sun exposure, prior melanoma, immunosuppression, family history) and complete skin and nodal exam. The lesion is concerning by the ABCDE criteria—Asymmetry, irregular Borders, multiple Colors, Diameter >6 mm, and Evolution (changing/bleeding). Meeting any one criterion warrants biopsy.
-
What is the correct biopsy technique for a suspected melanoma, and what should you avoid?
Expected answer
A full-thickness excisional biopsy with narrow (1–3 mm) margins down to the subcutaneous fat, oriented to allow later wide local excision. This gives accurate Breslow depth. Avoid shave biopsy (transects the lesion and understages depth) and avoid wide excision before diagnosis. For very large lesions or cosmetically sensitive sites, a full-thickness incisional/punch biopsy of the thickest area is acceptable.
-
Which pathologic features drive staging and treatment decisions?
Expected answer
Breslow depth (the single most important prognostic factor), ulceration, mitotic rate, and satellitosis. These determine margins and whether sentinel lymph node biopsy is indicated. Lesions ≤0.8 mm without ulceration or mitoses are considered low-risk.
-
Pathology returns a Breslow depth of 1.6 mm without ulceration. How do you treat the primary site and the nodal basin?
Expected answer
This is an intermediate/high-risk melanoma. Perform wide local excision with a 1–2 cm margin (1 cm for 1–2 mm depth, 2 cm for >2 mm) and sentinel lymph node biopsy. SLNB uses preoperative lymphoscintigraphy plus intraoperative gamma probe, with or without vital blue dye, and meticulous pathologic exam of the node. SLNB is indicated for tumors >0.8 mm or thin tumors with high-risk features.
-
What margins are recommended for wide local excision based on depth?
Expected answer
In situ: 0.5–1 cm. ≤1 mm: 1 cm. 1–2 mm: 1–2 cm. >2 mm: 2 cm. Margins balance local control against morbidity; for this patient at 1.6 mm a 1–2 cm margin is appropriate.
-
The sentinel node returns positive for micrometastasis. What is your next step?
Expected answer
Complete staging with CT chest/abdomen/pelvis with IV contrast or full-body PET/CT, and consider brain MRI. If there is no distant metastasis, options are nodal basin surveillance with ultrasound versus completion lymphadenectomy (most patients now undergo surveillance per MSLT-II), plus consideration of adjuvant systemic therapy (immunotherapy or targeted therapy) or a clinical trial.
-
If this patient had presented with a palpable axillary node, how would your workup and management differ?
Expected answer
Clinically node-positive disease requires staging imaging (CT C/A/P with contrast or PET/CT) plus FNA or core biopsy of the suspicious node to confirm. If disease is regional, proceed with wide local excision and therapeutic lymph node dissection, and consider adjuvant systemic therapy or a trial. If distant metastatic, treat with systemic therapy/clinical trial; resect limited metastatic disease only in carefully selected patients.
-
What is the appropriate long-term follow-up?
Expected answer
Complete skin exam every 3–12 months for the first 5 years, then at least annually for life. Imaging for any signs or symptoms of metastasis, and surveillance imaging every 3–12 months for 3 years for stage IIB–IV disease. Educate on sun protection and monthly skin self-examination.
What Residents Often Miss
- Performing a shave biopsy that transects the lesion and prevents accurate Breslow depth measurement and understages the tumor.
- Proceeding directly to wide local excision before establishing a tissue diagnosis and depth.
- Choosing excision margins arbitrarily rather than tailoring them to Breslow depth.
- Omitting sentinel lymph node biopsy in an intermediate-thickness melanoma (or doing SLNB on a clinically node-positive patient instead of node dissection after biopsy confirmation).
- Ordering extensive staging imaging for a thin, low-risk, clinically node-negative melanoma when it is not indicated.
- Failing to obtain FNA/core biopsy of a palpable node before committing to lymphadenectomy.
- Neglecting adjuvant systemic therapy referral and structured long-term skin surveillance with sun-protection counseling.
Want More Practice?
Run this case live with an AI examiner that pushes back, asks for operative detail, and grades you on the ABS competencies — then gives instant feedback.
Start practicing freeNo credit card required · 5 free practice cases
Keep Studying
This page is educational content for general-surgery board-exam practice. It is not medical advice and is not a substitute for clinical judgment, institutional protocols, or current primary literature.