Diagnosis of subclinical extramammary Paget's disease with a combination of noninvasive photodynamic diagnosis and reflectance confocal microscopy.

Extramammary Paget's disease is a rare skin malignancy, and its diagnosis requires invasive biopsy and histopathological examination. Surgery is the standard treatment for extramammary Paget's disease patients; however, as incision boundaries and the depth of tumor cell infiltration are often unclear, the postoperative recurrence rate is high. We present a case in which we used photodynamic diagnosis in combination with reflectance confocal microscopy before surgery to detect an extramammary Paget's disease lesion that was located 3 cm away from the classical lesion. This secondary lesion exhibited a subclinical presentation, and it was eventually confirmed as an extramammary Paget's disease lesion by pathological examination. During detection using our technique, we delineated the boundaries of the extramammary Paget's disease lesion as a guide for surgical excision. The findings of our case demonstrate that photodynamic diagnosis combined with reflectance confocal microscopy can be used for the noninvasive diagnosis of subclinical extramammary Paget's disease and may be used to guide strategies for planning treatment and preventing relapse.