Oral and maxillofacial sclerosing epithelioid fibrosarcoma: report of five cases

Sclerosing epithelioid fibrosarcoma (SEF) has distinctive morphology and occurs mainly in deep soft tissue of adult extremities. Approximately 59 cases of SEF have been reported, with only 12 previously described in head and neck locations. Lesions involving the oral and maxillofacial region (OMFR) and intraosseous examples are rare. We present five cases of OMFRSEF. The OMF Pathology Department Registry was searched for cases coded from 1990 to the present as "SEF," "fibrosarcoma not otherwise specified" or "neoplasm of uncertain histiogenesis." Inclusion required OMFR location, an abundantly sclerotic sarcoma with epithelioid features, and lack of other phenotype by immunohistochemistry. Five cases of SEF included 3 males and 2 females. The age of the patients were: 19, 22, 35, 47 and 47 years. Tumor location included the infra-temporal fossa, buccal mucosa (recurrence extending into bone), anterior mandible (intraosseous primary, focally extending into soft tissue), and left parotid and submandibular gland (with metaplastic bone) regions. Tumor sizes ranged from 1.0 to 5.7 cm, median 3.5 cm. Histologically, the tumors were well delineated and multinodular, separated by fibrous septae. The spindled to primarily epithelioid tumor cells formed moderately cellular sheets and cords of irregularly contoured medium to large, round to oval, occasionally overlapping nuclei, indistinct nucleoli, wispy eosinophilic (retracting) cytoplasm, and distinctive cytoplasmic borders, embedded in osteoid-like stroma. Hemangiopericytoid (HPC-like) vessels were observed. Despite numerous apoptotic cells, mitoses were generally low; necrosis was present in two cases. Three tumors were graded as 2/3 and two 1/3. Immunohistochemically, the tumor cells were positive for vimentin, 1 case focally for CD34, whereas all cases were negative for S100 protein, keratins, EMA, desmin, and SMA. Wide or radical excision was performed with no adjuvant therapy. Follow-up revealed that 4 cases recurred at a range of 12-120 months. One case had no recurrent/residual disease at 3 months. Metastatic disease was present in 2 cases, to chest wall and lumbar/thoracic spine at 12 and 21 months, respectively. One patient died of disease complications at 15 months. OMFRSEF occur in adults in various locations, but with a common propensity to involve bone; there is recurrent potential and morbidity with higher grade lesions. The differential diagnosis for these tumors in this site includes sclerosing carcinoma, Ewing/PNET, osteosarcoma, osteoblastoma, and benign and malignant myoepithelial salivary gland tumors. The collagen, focal spindle cell features, HPC-like vasculature, and weak focal CD34 reactivity in one case might have raised a possible relationship between OMFRSEF and low grade malignant solitary fibrous tumor, but the intraosseous propensity, epithelioid features and relative lack of CD34 make this a distinctive entity.