Scalp SCC on Irradiated Skin in a Patient on Apixaban
A 70-year-old woman on apixaban 5 mg twice daily for atrial fibrillation (CHA₂DS₂-VASc 5) and aspirin 81 mg for a prior TIA presents with a 2.1 cm biopsy-proven poorly differentiated squamous cell carcinoma of the left parietal scalp. She had whole-brain radiotherapy for a metastatic lesion four years ago; the scalp in that field is thin, dry, and telangiectatic, and there is exposed periosteum at the base of the tumour. Her last apixaban dose was this morning and her eGFR is 62. She is anxious about stroke and asks whether she can stop her blood thinner "for a week." Mohs with 5 mm margins and same-day reconstruction is planned.
1. Set out a perioperative anticoagulation plan and justify it. Address bridging, aspirin, and the specific pharmacology of apixaban.
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Continue apixaban. Evidence in cutaneous and Mohs surgery shows no clinically meaningful increase in major bleeding when direct oral anticoagulants are continued, and the thrombotic risk here is high (CHA₂DS₂-VASc 5, prior TIA). Apixaban has a ~12-hour half-life and twice-daily dosing, so it is fully cleared within about 24–48 hours - the reason "stop for a week" is both unnecessary and dangerous.
If she or the anaesthetist insists on interruption for a large flap:
- Hold two doses (the evening before and the morning of surgery), i.e., about 48 hours, and restart the evening after surgery once haemostasis is confirmed.
- Do not bridge with low-molecular-weight heparin. Bridging does not reduce arterial thromboembolism in this setting and clearly increases bleeding.
- Continue aspirin 81 mg. It is secondary prevention after TIA, and stopping it adds stroke risk without meaningful surgical benefit.
Intraoperative measures: meticulous cautery, pressure, tranexamic acid-soaked pledgets, a running locking suture or figure-of-eight for large defects, and avoiding large dead space. Confirm the plan with her cardiologist in writing. Also recognise that irradiated, poorly differentiated scalp SCC has a higher local recurrence rate, which argues for complete margin control over speed.
2. The Mohs defect exposes periosteum over the parietal bone in a previously irradiated field. Compare reconstruction options and justify your choice.
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The bed is the problem, not the size. Irradiated periosteum is poorly vascularised and unreliable as a graft bed; radiation also causes small-vessel obliterative change, so any reconstruction must bring its own blood supply.
Options, worst to best here:
- Split-thickness skin graft directly on irradiated periosteum: unpredictable take, high failure and breakdown risk. Acceptable only if periosteum is genuinely intact and well-vascularised.
- Healing by secondary intention: possible over periosteum but slow, painful, and prone to sequestrum if bone desiccates.
- Dermal substitute plus graft: a reasonable salvage but still depends on a vascularised bed and is expensive.
- Local transposition or rotation flap (or a galeal/pericranial flap): brings axial blood supply, gives durable coverage, and is my preferred option if a suitable pedicle exists outside the radiation field.
- Free tissue transfer: reserve for exposed dura or failed local options.
If calvarial bone is exposed, do not graft it - burr to punctate bleeding, or involve plastic surgery for flap coverage. Stage the reconstruction if margin clearance is uncertain rather than committing to a definitive flap on a possibly positive wound.
3. She asks what happens if the margins are positive after Mohs and whether she can simply have radiotherapy instead of more surgery.
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Mohs should achieve clear margins in most cases, so this is a contingency plan rather than a likely outcome - but it needs discussing because of the tumour's biology.
- Positive or very close margins after Mohs: re-excision is preferred where feasible; the field is already irradiated, so further radiotherapy to the same site is constrained by cumulative dose to brain and scalp. Adjuvant radiotherapy is generally reserved for perineural invasion, extensive bone or nerve involvement, immunosuppression, or where re-excision would be morbid.
- Definitive radiotherapy instead of surgery: an option if she declines or cannot tolerate surgery, but poorly differentiated tumours of this size behave aggressively, radiotherapy takes weeks, and the field has already received whole-brain treatment.
- Practical points: confirm the margin status in writing, discuss her case at a multidisciplinary tumour board, and verify her aspirin and apixaban are restarted promptly - the commonest serious harm in this vignette is a stroke from over-cautious withdrawal, not the skin wound.