Dedifferentiation of Metastatic Recurrent Chondrosarcoma of the Right Distal Femur Into High-Grade Sarcoma Favouring Leiomyosarcoma: A Report of a Rare Case With Review of Literature.

Dedifferentiated chondrosarcoma (DDCS) is a rare and aggressive biphasic bone malignancy that accounts for a small but distinct proportion of all chondrosarcomas and primary malignant bone tumours. The high-grade dedifferentiated component most commonly resembles undifferentiated pleomorphic sarcoma or osteosarcoma. The prognosis is dismal, with low five-year overall survival rates that are further reduced in the presence of metastatic disease. Local recurrence occurs in a substantial proportion of patients even after wide-margin resection, and distant metastasis, most frequently to the lungs, is common. Systemic therapy offers limited benefit, with poor overall response rates and no durable remissions with currently available doxorubicin-based, ifosfamide-based, or targeted regimens. Leiomyosarcomatous dedifferentiation within DDCS is exceptionally rare, with only a handful of cases documented worldwide. We report a case in which a patient who underwent limb-salvage surgery for DDCS of the right distal femur in 2023 re-presented two years later with extensive metastatic local recurrence requiring palliative hip disarticulation. Immunohistochemical profiling of the resected specimen demonstrated a smooth muscle differentiation profile consistent with high-grade sarcoma favouring leiomyosarcoma arising within the dedifferentiated component, a finding with important implications for prognostication and systemic therapy selection. This case highlights the critical role of comprehensive tissue sampling, immunohistochemical subtyping, and multidisciplinary management in diagnostically complex bone sarcomas.

Authors

Yedla SVV; Mishra P; Karpurmath SV

Published

Jan 1, 2026

Journal or venue

Cureus

DOI

10.7759/cureus.108543

Paper type

journal article

Source

Pubmed