• Reflectance confocal microscopy proved its utility in the differential diagnosis of Paget’s disease and good concordance with histopathology • Photodynamic diagnosis provided false-positive fluorescence in patients previously treated with radiotherapy • Extramammary Paget disease patients at high-risk for local recurrences and disease progression require close surveillance, multi-line treatment or enrollment to clinical trials • Immunotherapy with balstilimab demonstrated a clinical benefit in one patient Mammary and extramammary Paget disease (PD; MPD, EMPD) is a rare neoplastic disorder characterised by intraepithelial infiltration of malignant cells with glandular differentiation. Diagnosis of PD remains challenging, as its clinical presentation frequently mimics inflammatory diseases or other cutaneous neoplasms. It is estimated that approximately 10–15% of EMPD cases and up to 50% of MPD cases are invasive at the time of definitive diagnosis, largely due to diagnostic delays that may last several years. In this retrospective case series, we analysed non-pigmented EMPD (n = 8) and MPD (n = 5) to evaluate the diagnostic performance of selected non-invasive imaging techniques, including dermoscopy, photodynamic diagnosis, and reflectance confocal microscopy, highlighting their limitations and advantages during the primary investigation and disease surveillance over several years. Furthermore, we analysed diagnostic challenges in advanced, metastatic, and overlapping cases. The study also summarises the outcomes of multiple-line therapeutic approaches applied in high-risk EMPD patients and compares these results with data available in the current literature.
Słowińska et al. (Sun,) studied this question.