Extramammary Paget disease presenting with pathological burst fracture due to spinal metastasis: a rare case report

Background: Extramammary Paget disease (EMPD) is a rare intraepithelial adenocarcinoma with an estimated annual incidence of about one per million people that often mimics benign, chronic ulcerations, contributing to diagnostic delays of months to years. Spinal metastasis can cause pathologic fractures leading to spinal cord compression, severe pain, and paralysis that greatly reduce quality of life. Case presentation: A 73-year-old male with inguinal EMPD presented with progressive back pain and right leg weakness. Positron emission tomography/computed tomography on 26 January 2026 showed an L1 pathological burst fracture suspicious for metastasis. Initial chemotherapy was chosen due to moderate pain. By April, pain reached a visual analog scale score of 9, weakness worsened, and the patient became bedridden [Karnofsky Performance Status (KPS) 40%, Frankel C]. After multidisciplinary review, surgical decompression was performed. Postoperative histopathology of the L1 biopsy was reported as metastatic poorly differentiated carcinoma. In the clinical context of known EMPD, the lesion was considered presumptively related to EMPD; however, definitive attribution was limited by the unavailability of a comparative pathology review and immunohistochemical studies. Conclusion: This case highlights EMPD as a rare disease that metastasizes to the spine and causes burst fractures. Initially, the clinical presentation often mimics benign, chronic ulcerations, which can delay diagnosis. The Tokuhashi score of 7and Spinal Instability Neoplastic Score of 11 provided objective justification for palliative surgical decompression. Surgical intervention achieved meaningful functional improvement from a bedridden state (KPS 40%, Frankel C) to ambulation with assistance (KPS 60%, Frankel D). Timely surgical decompression, combined with multidisciplinary oncological care, can improve functional outcomes and quality of life in metastatic EMPD despite a limited predicted survival.