Extraskeletal mesenchymal chondrosarcoma: oligometastatic disease and effect of multimodal treatment

A 24-year-old female was diagnosed in 2018 with extraskeletal mesenchymal chondrosarcoma (MCS) of the left elbow (4 × 5 × 3 cm, antecubital fossa). TRU-CUT biopsy confirmed diagnosis neoadjuvant 3D conformal radiotherapy (RT) (25 Gy in 5 × 5 Gy fractions) was followed by R0 resection. Adjuvant chemotherapy (CHT) (VADRIAC: vincristine, actinomycin D, doxorubicin, ifosfamide, cyclophosphamide) was initiated. In Dec 2018, CT revealed pulmonary M1; thoracotomy achieved R0 resection of three nodules. CHT continued with EIAO (etoposide, ifosfamide, adriamycin, vincristine; total doxorubicin 1010 mg). FISH analysis excluded NR4A3 and DDIT3 rearrangements, confirming extraskeletal MCS (SOX9+, SOX10–). Platinum-based CHT (cisplatin–etoposide) was introduced. progressive disease (PD) in lungs by RECIST 1.1 (June 2019) led to first-line palliative CHT with gemcitabine (900 mg/m², D1 + 8) and docetaxel (75 mg/m², D8), achieving partial response (PR). In early 2020, liver M1 appeared (up to 24 × 19 mm). A second pulmonary metastasectomy was performed (December 2020). With further PD (mid-2021), VAI (vincristine, actinomycin D, ifosfamide) was administered for 7 cycles, achieving PR. Due to isolated mediastinal progression, RT (45 Gy in 15 × 3 Gy fractions) was delivered (October 2021) resulting in PD. Temozolomide-irinotecan failed (PD), as did rechallenge with gemcitabine-docetaxel (PD, January 2022). In Mar 2022, the patient developed symptomatic CNS metastases (largest 23 × 22 mm, frontoparietal region). Palliative care was initiated, and she died at home shortly after. The patient underwent eight systemic regimens over four years with initial PRs but eventual PD and CNS involvement.