Total Femoral Replacement for Complicated Echinococcus Infection: Sixteen-Year Follow-up.

CASE: Osseous hydatidosis caused by Echinococcus is rare, especially in long bones. To the best of our knowledge, this is the third femoral hydatidosis case with successful osseous eradication through total femoral resection and total femoral megaprosthesis. Unlike the previous 2 cases, we uniquely illustrate recurrent soft-tissue hydatidosis episodes requiring additional hydatid resections for local control with no evidence of disease at final 16-year follow-up, the longest follow-up period of the 3 reported cases. CONCLUSION: Despite radical bone resection for osseous hydatidosis eradication, additional complex surgical interventions may be needed to locally control soft-tissue disease.

Intra-articular Extraskeletal EWSR1-Negative NR4A3-Positive Myxoid Chondrosarcoma: A Case Report.

CASE: Extraskeletal myxoid chondrosarcomas (EMCs) are rare soft-tissue malignancies. Intra-articular occurrence is even more rare. To our knowledge, this case is one of only 2 reported intra-articular EMC cases of the knee free of local recurrence and/or amputation at follow-up. This case is also distinctive for being fluorescence in-situ hybridization-negative for the typical EMC-balanced translocation t(9;22) which fuses EWSR1 with NR4A3, harboring instead a variant translocation resulting in fusion of NR4A3 with a less common gene fusion partner. CONCLUSION: This is a unique case of intra-articular EMC of the knee with a rare molecular fingerprint and an unusually positive outcome.