Vulvar cancer on lichen sclerosus with a focal ulcer — structured oral station (12 minutes)

Opening prompt — "Stage this lesion and explain your reasoning."

Model response — the FIGO 2021 stage: ^[1]

• "This is Stage IB vulvar squamous cell carcinoma. Stage IB is a tumour over 2 cm in size or with stromal invasion over 1 mm, confined to the vulva with negative nodes. This tumour is 2.5 cm with 4 mm of invasion."
• "Depth of invasion in the 2021 system is measured from the basement membrane of the deepest adjacent dysplastic, tumour-free rete ridge to the deepest point of invasion — a change from the older dermal-papilla method."^[1]

Probe 1 — "Describe the surgical management of the primary tumour and the groin."

• "The primary tumour is managed by wide local excision (radical local excision) with a 1 to 2 cm margin through healthy tissue to the deep fascia. Radical vulvectomy is reserved for large, multifocal or locally advanced disease." ^[1]
• "The groin is managed by sentinel lymph node biopsy — the standard for early-stage, unifocal, node-negative disease. Because this lesion is lateralised on the right labium majus, over 1 cm from the midline, ipsilateral sentinel biopsy suffices; inguinofemoral lymphadenectomy is performed only if the sentinel node is positive." ^[2]

Probe 2 — "Reproduce the GROINSS-V evidence for sentinel node biopsy."

• "GROINSS-V enrolled 377 women with unifocal T1 squamous cell carcinoma under 4 cm who underwent the sentinel node procedure, with inguinofemoral lymphadenectomy only for sentinel metastases." ^[2]
• "At a median follow-up of 105 months, the isolated groin recurrence rate was 2.5 percent at 5 years for sentinel-node-negative patients, and disease-specific 10-year survival was 91 percent for sentinel-negative versus 65 percent for sentinel-positive. This is the safety evidence that made sentinel biopsy the standard." ^[2]

Probe 3 — "What is the morbidity argument for sentinel biopsy over full lymphadenectomy?"

• "Per the Rahm 2022 population-based study, persisting lymphoedema is about 4 percent after sentinel biopsy versus about 39 percent after inguinofemoral lymphadenectomy; infection about 15 percent versus about 36 percent." ^[4]
• "Lymphoedema is near-ubiquitous when adjuvant groin radiotherapy follows a full lymphadenectomy — the double hit. Sentinel biopsy avoids both." ^[4]

Probe 4 — Contrast: "How does this relate to VIN, and to the lichen sclerosus?"

• "This tumour arose on lichen sclerosus via the HPV-independent pathway — differentiated VIN, keratinising SCC, older women. The other pathway is HPV-associated: usual-type VIN (warty/basaloid), basaloid SCC, younger women." ^[1][3]
• "VIN is managed by the 3-step approach: biopsy to exclude invasion; treat (excision, laser, imiquimod for usual type); surveil and treat the lichen sclerosus with ultrapotent corticosteroid. Differentiated VIN demands excision because of its high invasive potential." ^[3]

Probe 5 — Communication: "How do you explain the plan to this woman?"

• "I would say: 'The biopsy confirms a skin cancer on the vulva — a squamous cell carcinoma — that has arisen on your lichen sclerosus. The good news is that it is small and the lymph nodes feel normal. I will remove it with a margin of healthy skin, and check the lymph glands on that side with a tracer test called a sentinel node biopsy — this is far gentler than removing all the glands. If that node is clear, we will not need to remove more glands. We will also treat your lichen sclerosus with a strong ointment to lower the chance of this coming back, and see you regularly for the long term.' "^[1][3]