Extramammary Paget disease (EMPD) involving the perianal region is rare and challenging to manage. Primary EMPD involves stand-alone noninvasive lesions within the epidermis, while secondary EMPD involves phenotypically similar lesions derived from separate underlying malignancies. Differentiating between primary and secondary EMPD is challenging when no underlying malignancies are detected during workup. Continued reporting of perianal EMPD cases is encouraged so that risk stratification can be improved and patients can be managed with an appropriate level of aggressiveness. Herein, we report the case of a 74-year-old woman who chose aggressive surgical management after being diagnosed with perianal pagetoid intraepithelial carcinoma from a suspected occult underlying primary colorectal tumor.