Mesenchymal Chondrosarcoma Presenting as Deep Vein Thrombosis: A Case Report Highlighting Diagnostic Pitfalls and the Role of Imaging–Pathology Correlation

Abstract

Mesenchymal chondrosarcoma (MCS) is a rare, aggressive malignancy that can arise in either bone or soft tissue, typically affecting young adults in the second to third decades of life. Its hallmark biphasic histology—comprising undifferentiated small round cells interspersed with islands of cartilaginous differentiation—poses diagnostic challenges, as it can mimic other small round blue cell tumors. Because radiographic features are often nonspecific, accurate diagnosis requires careful integration of imaging, histopathologic, and immunohistochemical findings. We report the case of a healthy 26-year-old woman with a large juxtacortical mass arising from the left superior pubic ramus. Imaging revealed a lobulated, mineralized lesion with cortical origin and matrix calcification. This case is notable for its rare pelvic site and juxtacortical location, as well as its unusual initial presentation with iliofemoral deep venous thrombosis due to extrinsic venous compression. These findings underscore the diagnostic complexity of MCS and highlight the importance of considering this entity in the differential diagnosis of juxtacortical pelvic masses.