KEY POINTS
- Interesting Image case report of a 76-year-old woman with secondary vulvar extramammary Paget disease of likely anorectal origin treated with radical radiotherapy after surgery was not pursued.
- Treatment used volumetric modulated arc therapy: 59.4 Gy in 33 fractions to the vulva, perianal region, and lower rectum, and 50.4 Gy in 1.8 Gy fractions to internal iliac and bilateral inguinal nodes.
- The patient was treated in the frog-leg position using Vac-Lok immobilization, full-bladder protocol, daily surface-guided radiotherapy, and cone beam computed tomography verification.
- Mean setup shifts after surface-guided setup were 0.17 cm anterior-posterior, 0.05 cm superior-inferior, and 0.08 cm medio-lateral; Figure 3 shows shifts remaining close to zero across treatment fractions.
- During treatment, the patient developed grade 2 radiation dermatitis; at 1 month post-treatment, complete clinical response was reported with postradiation hyperpigmentation and no active disease.
CLINICAL TAKEAWAY
This case supports surface-guided radiotherapy as a useful setup and intrafraction monitoring aid for technically difficult vulvar or perineal treatments in the frog-leg position. The practical value is workflow-related: faster initial alignment, fewer repeat cone beam computed tomography acquisitions, and improved patient comfort in an unstable posture. The evidence is very limited because this is a single case report with short follow-up and no comparator, so it should be treated as a useful technical example rather than validated practice evidence.