Screening for associated malignancies in vulval Paget disease clarified

This issue of the BJD carries an important article that helps to clarify which patients with vulval Paget disease (VPD) should be screened for a second malignancy. It is the first article to focus on cutaneous noninvasive VPD. VPD is a rare disease of elderly women and a form of extramammary Paget disease (EMPD) occurring much less frequently than mammary Paget disease (9 : 1). VPD may be classified according to origin and invasion. Type 1 primary VPD tumours are of cutaneous origin (1a, noninvasive; 1b, invasion; 1c, arising with a vulval adenocarcinoma) and secondary tumours arising from intestinal malignancy (type 2) or a urological malignancy (type 3). Primary VPD can be regarded as the only true VPD as secondary tumours (types 2 and 3) are due to expansion/direct spread from the urological or intestinal tumour. Primary cutaneous noninvasive VPD (1a) is the type most frequently encountered. The authors analysed a cohort of 199 women with VPD against a control group of women without VPD using two Netherlands databases, a registry of histopathology and cytopathology and a national cancer registry. Overall, for all types of VPD the risk of developing a secondary malignancy was significantly increased compared with the normal population, mainly due to intestinal and urological malignancies. There was no increase in breast cancer diagnosis. Importantly there was no statistically increased risk of cancer diagnosed within 3 years after diagnosis of primary noninvasive cutaneous VPD. Studies evaluating cancer associations in VPD to date have largely been performed without age-matched controls and, thus, risk may have been overestimated in an elderly population where cancer diagnoses are likely to be more frequent. Furthermore, some studies did not clearly delineate time course, including malignancies that presented significantly before or after a diagnosis of VPD. Some studies included underlying secondary urological and bowel tumours (types 2 and 3 VPD) and invasive VPD while others did not. Several studies have reported that perianal localization is a risk factor for intestinal cancer in EMPD. Current practice has been to screen all women with VPD for other malignancies, although in our personal practice in a tertiary joint dermatology/gynaecology–oncology clinic, we have not identified any secondary tumours in noninvasive cutaneous EMPD from screening in over 10 years. A weakness of the study is that pathology reports were used as the basis of diagnosis and immunocytochemistry was not performed in all. It is not possible to distinguish primary and secondary tumours on histological examination alone. When a diagnosis was not clear (66 8%) it was assumed that VPD was primary cutaneous. This may have led to an overestimation of cancer risk as it is possible that some secondary VPD may have been included inadvertently. It is also possible that some cases of malignancy could have been missed due to incomplete data. What does this mean in practice? All women with suspected VPD must be biopsied and appropriate immunocytochemistry performed to help distinguish between primary and secondary VPD. Those with secondary VPD/EMPD or invasive VPD/ EMPD must continue to be examined and investigated for underlying malignancy in the bowel and urinary tract as malignancy is strongly associated. Those with a profile suggesting primary cutaneous VPD/EMPD (1a) may not require routine screening unless clinical symptoms and signs suggest otherwise. Unnecessary, invasive and expensive tests may be avoided.