Peritoneal Sarcomatosis Secondary to Conventional Chondrosarcoma: A Case Report.

Chondrosarcoma is one of the most common primary malignant bone tumors and typically metastasizes hematogenously, most frequently to the lungs. Peritoneal dissemination is an exceptional presentation, usually associated with dedifferentiated subtypes or tumor rupture, and lacks standardized management strategies. We report the case of a 27-year-old male who presented with a large pelvic-abdominal mass and severe left lower-limb edema. Imaging revealed a large calcified tumor arising from pelvic zone III. Biopsy suggested a grade 1 conventional chondrosarcoma. The patient underwent an intraperitoneal surgical approach, during which spontaneous tumor rupture, hemoperitoneum, and peritoneal implants were identified. Complete macroscopic cytoreduction (CC-0) was achieved through type III internal hemipelvectomy, omentectomy, and resection of peritoneal implants. Final pathology confirmed grade 2 conventional chondrosarcoma with peritoneal involvement. The postoperative course was uneventful. The patient is currently receiving individualized adjuvant systemic therapy and shows no evidence of disease at early follow-up. Peritoneal sarcomatosis secondary to conventional chondrosarcoma is exceedingly rare. This case highlights that aggressive surgical management may be feasible in carefully selected patients and underscores the importance of multidisciplinary care in specialized sarcoma centers.