A Pigmented Lesion on the Back of a 58-Year-Old
A 58-year-old man asks about a mole on his upper back that his wife says has changed over the past year. It is 9 mm, asymmetric, with irregular borders and two shades of brown; it does not itch or bleed. He has fair skin, a history of blistering sunburn as a child, and a father who had melanoma at age 70. Examination shows no palpable axillary or supraclavicular nodes; the rest of the skin exam reveals several benign-appearing nevi. He is otherwise well. He asks whether it can be "burned off" and whether he needs a lymph node biopsy.
1. What is the appropriate diagnostic procedure, and why not shave or destructive removal?
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Full-thickness excisional biopsy with a narrow margin (1–3 mm) and orientation for the pathologist.
Why not shave/curettage/laser:
- A suspicious pigmented lesion requires complete histologic assessment of Breslow thickness, which determines prognosis and surgical margins. A shave biopsy can transect the base of a melanoma, making thickness unmeasurable and potentially understaging the disease.
- Destructive methods (cautery, laser) destroy tissue and preclude histology entirely-unacceptable for a lesion with ABCDE features.
- Partial/punch biopsy is acceptable only for large or cosmetically sensitive lesions (e.g., face) where complete excision is impractical, and even then the deepest portion must be sampled.
Practical details: Orient the specimen (e.g., suture at 12 o'clock), send for permanent section, and avoid Mohs for initial diagnosis of melanoma. Document the clinical description and measurement. If the lesion is on the back, plan excision along relaxed skin tension lines for cosmesis.
2. The biopsy shows melanoma, Breslow 1.8 mm, ulcerated, mitotic rate 3/mm². What staging information and surgical plan follow?
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Staging: Breslow 1.8 mm with ulceration is at least T2b. Mitotic rate is no longer part of AJCC 8th edition T-staging for thin melanomas but supports biologic aggressiveness. Sentinel lymph node biopsy (SLNB) is indicated for T2b and above (and generally discussed for T1b).
Surgical plan:
- Wide local excision with 1–2 cm margins. For Breslow 1.01–2 mm, guidelines support 1–2 cm margins; 1 cm is acceptable and often preferred for cosmesis on the back, but 2 cm is used for higher-risk lesions. Choose based on thickness, location, and ability to close.
- SLNB should be performed, ideally at the same operation as wide excision to avoid a second procedure; inject radiotracer (and blue dye) around the biopsy site/scar.
- Do not perform elective complete lymph node dissection based on a positive SLNB in the current era-MSLT-II showed no melanoma-specific survival benefit; instead, ultrasound surveillance of the nodal basin is standard, with completion dissection reserved for macroscopic nodal disease.
Staging workup: For stage IB–II, routine imaging is generally not required unless symptoms; consider cross-sectional imaging if higher-stage features or symptoms. Baseline labs and dermatologic follow-up.
3. How do you counsel him about prognosis, follow-up, and family risk?
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Prognosis: Stage IB–II melanoma (T2b) has generally favorable but not trivial risk; 5-year melanoma-specific survival is roughly in the 80–90% range for T2b, with risk of recurrence highest in the first 2–3 years. Avoid quoting a single number as certainty; frame as risk ranges and the purpose of surveillance.
Follow-up:
- Skin and nodal exam every 3–6 months for the first 2–3 years, then less frequently, with ultrasound of the draining basin if SLNB was done or if nodes are difficult to examine.
- Sun protection and self-examination education.
- Imaging only for symptoms or suspected recurrence; routine surveillance imaging is not universally recommended for early-stage disease.
Family risk: A first-degree relative with melanoma increases his risk and his family's risk. Advise first-degree relatives to have skin examinations and practice sun protection. Genetic testing (e.g., CDKN2A) is not routine for a single melanoma without additional family history or multiple primaries; refer to genetics only if additional features emerge.
Counseling on "burning off": reinforce that the biopsy was necessary and that complete excision with margins is the treatment, not destruction.