Primary sclerosing epithelioid fibrosarcoma of the spine: a single-institution experience.

Aim to present our experience on spinal sclerosing epithelioid fibrosarcoma (SEF) and review the existing literature pertaining to SEF of the spine. Methods and results six cases of spinal SEF were reviewed and a literature search of all primary SEF of the spine was performed. All tumors occurred in adults (median age 41 years) and were located all along the spine, being the lumbar vertebrae the most commonly involved. All patients presented pain of months duration. Mean tumor size at diagnosis was 5.2 cm. Five tumors exhibited a spectrum of microscopic features consistent with pure SEF and one showed a hybrid morphology with areas of low-grade fibromyxoid sarcoma. All were diffusely and strongly positive for MUC4. Two cases were initially misdiagnosed as epithelioid haemangioendothelioma and aggressive chondroblastoma. FISH showed rearrangements of either FUS or EWSR1 in four cases. RT-PCR, identified the presence of FUS-CREB3L1 and EWSR1-CREB3L1 fusion transcripts in two cases and one case, respectively. Of five patients with follow-up data available, two developed one or more local recurrences and three patients had metastatic disease. Distant metastases were mainly to other osseous locations followed by lung and lymph nodes. At last follow-up, three patients died of disease and one was alive with multiple metastases. Conclusions SEF is an aggressive sarcoma that can involve the spine. It is important to recognize the spine as primary location of SEF to avoid misdiagnosis with more common primary spinal neoplasms, which can impact therapeutic approaches.