"Clock mapping" prior to excisional surgery in vulvar Paget's disease: tailoring the surgical plan

Paget disease is a rare neoplasm of the skin that mainly involves the vulvar region. Vulvar Paget's disease (VPD) can spread beyond the apparent edges of the lesion resulting in a high risk of involved surgical margins. Our aim is to verify the efficacy of a preoperative vulvo-vaginal intensive clock mapping in the prediction of the invasiveness and the extension of VPD.

All consecutive patients with primary VPD referred to our institution from July 2005 to December 2018 were subjected to a preoperative intensive biopsy mapping (clock mapping) of the vulvo-vaginal area: inside and outside the vulvar skin visible lesion, according to o'clock positions, and in the vagina. Patients with positive biopsies "only inside" or "also beyond" the visible lesion were included, respectively, in Group A and B. Surgical excision was drawn passing by the points with negative histology. Pathological findings of mapping biopsies were compared with those from radical surgery.

A total of 28 women were enrolled. After clock mapping definitive histology: 17 (60.7%) and 11 (39.3%) patients were included in Group A and B. Definitive histology showed non-invasive, micro-invasive and invasive VPD, respectively, in 13 (46.4%), 11 (39.3%) and 4 (14.3%) patients, with 4 patients further upstaged. Overall, negative margins were found in 14 (50%) patients: 9 (32.1%) from Group A and 5 (17.9%) from Group B. In 23 cases (82.1%), clock mapping identified free surgical margins along the vulvo-perineal skin excision front.

Preoperative clock mapping emerged as potentially useful workup tool to predict invasiveness and extension of VPD, to tailor surgical excision.