Locally advanced malignant solitary fibrous tumour successfully treated with conversion chemotherapy, operation and postoperative radiotherapy: a case report

Preoperative diagnosis of solitary fibrous tumour (SFT) may not provide a complete tumour picture and may be inaccurate. There is no standard treatment for locally advanced or metastasised malignant SFT (MSFT). Here, the case of a 17-year-old male patient with final pathology diagnosis of MSFT is reported. Preoperative biopsy pathology results suggested an Ewing sarcoma that was positive for CD99 antigen, vimentin, friend leukaemia integration 1 transcription factor, apoptosis regulator Bcl-2, and synaptophysin; and negative for CD34 antigen, S-100 protein (S-100), smooth muscle antigen, cytokeratin, and Wilms tumour 1 associated protein. The Ki67 positive rate was 8%, so the patient initially received eight cycles of conversion chemotherapy (vincristine, etoposide, ifosfamide and pirarubicin for one cycle, and vincristine, doxorubicin, and cyclophosphamide/ifosfamide and etoposide for 7 cycles in total). The tumour shrunk significantly and was surgically removed. The final pathology diagnosis was MSFT that was positive for CD99 and signal transducer and activator of transcription 6, and negative for CD34, tumour protein 63, S-100, desmin, and epithelial membrane antigen. Fluorescence in situ hybridization showed no gene translocation in EWS RNA binding protein 1, SS18 subunit of BAF chromatin remodelling complex or FUS RNA binding protein. The patient finally accepted adjuvant radiotherapy of 5600 cGy. Disease-free survival has been > 1 year, with no recurrence or metastasis detected to date. MSFT is rare and treatment for locally advanced or metastatic MSFT remains controversial. The efficacy of the present therapeutic strategy requires further research.