A Pregnant Woman with a New Pigmented Lesion
A 31-year-old woman, 24 weeks pregnant, is referred urgently because a pigmented lesion on her left calf has 'changed'. She noticed it 3 years ago as a small brown spot; over the last 4 months it has enlarged and become irregular. She is fair-skinned with many naevi and a history of severe sunburn in adolescence. Examination shows a 9 mm asymmetric macule with irregular, notched borders and variegated brown-black pigmentation; dermoscopy shows atypical network, irregular dots/globules and a blue-white veil. There is no palpable lymphadenopathy. She is anxious about the effect of any procedure on the pregnancy and asks whether it can wait until after delivery.
1. What is your assessment and what do you recommend regarding timing of biopsy?
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Assessment: the clinical and dermoscopic features (asymmetry, irregular notched border, variegated colour, atypical network, irregular dots/globules, blue-white veil) are highly suspicious for melanoma. Pregnancy does not make melanoma benign, and pregnancy-associated changes in naevi are usually symmetrical and uniform - these features are not explained by pregnancy.
Recommendation: excise or biopsy now; do not defer until after delivery. Delay risks progression and nodal spread. Excision under local anaesthetic with lidocaine is safe in pregnancy; the procedure is minor and can be done in the second trimester without fetal risk. Perform an excisional biopsy with a narrow margin (2 mm) for histology; avoid shave biopsy of a suspected melanoma. Send for Breslow thickness, mitotic rate and ulceration.
Counsel: explain that staging and prognosis depend on prompt diagnosis; that surgery and local anaesthesia carry negligible fetal risk; and that if melanoma is confirmed, sentinel lymph node biopsy can be performed safely in pregnancy (using blue dye and/or radiolabelled colloid with appropriate precautions) and should be discussed with the MDT.
2. Histology confirms a 1.8 mm Breslow melanoma with 3 mitoses/mm² and no ulceration. How do you stage and counsel her about pregnancy and prognosis?
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Staging: T2b (Breslow 1.01–2.00 mm with mitoses ≥1/mm², non-ulcerated). Sentinel lymph node biopsy is indicated for staging at this thickness; it can be performed in pregnancy with multidisciplinary input. If node-negative, stage IB–IIA depending on final nodal status.
Counselling points:
- Prognosis is driven by Breslow thickness, mitotic rate and nodal status; 1.8 mm non-ulcerated melanoma has a substantial 10-year survival but warrants close follow-up.
- Pregnancy does not worsen melanoma outcome in most studies; the priority is timely treatment. There is no evidence that termination or early delivery improves prognosis.
- Wide local excision with 1–2 cm margins can be performed in pregnancy; timing should be discussed with obstetrics, but generally can proceed in the second trimester.
- Follow-up: 3-monthly clinical review for 2–3 years, then 6-monthly; educate on self-examination and sun protection.
- Future pregnancies are not contraindicated; discuss contraception and timing of any systemic therapy if needed.
- Sentinel node biopsy results guide whether adjuvant therapy or nodal surveillance is needed; discuss with oncology.