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Pure Chondrosarcomatous Heterologous Component Presenting As A Gastric Mass
Location: 65
Mentor: Dr. Oleksandr Kryvenko
A 76-year-old woman with no significant past medical history was evaluated for a presumed gastric mass. CT imaging revealed an 18 cm dominant mass with multiple mesenteric vessels coursing through it, along with numerous peritoneal and mesenteric nodules with focal calcification. Endoscopic ultrasound showed an intramural mass compressing the gastric greater curvature. A core needle biopsy was performed. Histopathologic analysis showed a cartilaginous neoplasm with an adjacent spindle cell component. Tumor cells were located in lacunae with moderate atypia and binucleation, surrounded by a hyaline cartilage-like matrix. Enlarged atypical spindle cells were also present. Chromogenic in situ hybridization (CISH) demonstrated MDM2 amplification. Immunohistochemistry for IDH1 revealed only faint focal cytoplasmic staining. These findings supported a diagnosis of dedifferentiated liposarcoma (DLPS) with a chondrosarcomatous heterologous component. The biopsy lacked a clear lipogenic component, making the tumor closely resemble a conventional chondrosarcoma. Given that the mass was unresectable, distinguishing between DLPS and conventional chondrosarcoma had important therapeutic implications. DLPS may respond to targeted therapies such as anti-MDM2 or CDK4 inhibitors, while the chondrosarcomatous component is likely resistant to standard chemotherapy. Clinical and radiologic correlation was critical in identifying the tumor’s origin and guiding appropriate diagnostic and treatment decisions.
