INI-1 Loss with brachyury positivity unmasking a cervical poorly differentiated chordoma initially diagnosed as epithelioid sarcoma: a case report

Introduction Poorly-differentiated chordoma is a rare, aggressive tumor that can mimic epithelioid sarcoma, particularly when biopsies show epithelioid morphology with INI-1 loss. Case presentation A 31-year-old man presented with neck pain and a cervical mass and underwent resection in 2018, followed by radiotherapy, chemotherapy, and spinal stabilization. The lesion was initially classified as epithelioid sarcoma, and subsequent recurrences in 2022 and 2025 were interpreted similarly. However, re-evaluation of all specimens demonstrated pan-keratin positivity, loss of INI-1, and nuclear brachyury expression, prompting revision of the diagnosis to poorly differentiated chordoma. Results & conclusion This case underscores the importance of early brachyury testing in INI-1–deficient axial or paraspinal epithelioid tumors to avoid misdiagnosis and guide appropriate management.