Squamous cell carcinoma arising from perianal hidradenitis suppurativa treated with a combination of immunotherapy and radiotherapy

Background: Extramammary Paget's Disease (EMPD), a slow growing skin condition, is often associated with an internal malignancy.Primary EMPD presents in the absence of other malignancy.We present the patient outcomes from 4 cases of primary EMPD managed with slow Mohs margin control, of one surgeon operating from Addenbrooke's Hospital, Cambridge.Methods: Patients were identified using the EPIC record of patients who received slow Mohs surgery by the senior author between 20-April-2017 and 05-October-2024.4 male patients, aged between 65 and 80 years old, received slow Mohs surgery for EMPD of the groin.Results: After complete excision, the average margin around the lesion removed was 42mm (range: 12-117mm).2 patients required >1 excision to completely remove EMPD; the average number required was 3.5.Patients waited on average 48 days between subsequent excisions.One patient required 9 excisions to completely excise EMPD.Procedures were either under general (n=3) or local (n=1) anaesthesia.In between excision and reconstruction operations, all patients had their wounds closed rather than dressed. 1 patient is still undergoing slow Mohs procedures and has been excluded from follow up data.After a minimum follow-up period of 18-months, 0 patients experienced recurrence following completion of their Mohs procedures.However, on histopathological analysis, 1 patient's lesion was negative for EMPD.Conclusions: EMPD commonly has ill-defined margins which poses a challenge for complete excision.Slow Mohs overcomes this by allowing accurate margin analysis, facilitating exact locations of residual disease, so further excisions can be focused and tissue preserving.Slow Mohs provides reassurance that all EMPD is removed, evidenced by the 0% recurrence rate in those who have completed their treatment.These patients demonstrate the complexity of removing all EMPD, as after the first excision there is no surface indication of the disease.