Sclerosing epithelioid fibrosarcoma
Sclerosing epithelioid fibrosarcomas are rare slow-growing malignant fibroblastic soft tissue neoplasms pictured by a dense sclerotic hyalinized stroma with cords and areas of epithelioid fibroblasts.
Epidemiology
The tumor is rare and usually found in the middle-aged and elderly population. There is no gender predominance .
Associations
Sclerosing epithelioid fibrosarcomas are related to low-grade fibromyxoid sarcomas.
Clinical presentation
The typical complaint is a soft tissue mass. The duration varies but more than 30% of patients report a recent enlargement or pain.
Pathology
Sclerosing epithelioid fibrosarcomas are malignant tumors characterized by cords or nests of epithelioid cells within a dense hyalinized stroma .
Etiology
The etiology of sclerosing epithelioid fibrosarcomas is unknown.
Location
Sclerosing epithelioid fibrosarcomas are most often found in the deep soft tissues in the following locations:
- upper or lower extremities
- limb-girdle
- trunk
- head and neck
Rare locations include the pelvis, retroperitoneum, abdominal cavity or bones .
Macroscopic appearance
Grossly sclerosing epithelioid fibrosarcomas are firm, lobular well-demarcated tumors of grey-white color. They usually involve the deep muscles and muscular fascia or adhere to the periosteum. There might be calcifications .
Microscopic appearance
The microscopic appearance of sclerosing epithelioid fibrosarcomas includes the following :
- nests, cords or sheets of monomorphic epithelioid cells in a hyalinized sclerotic extracellular matrix
- margins can infiltrate into adjacent muscle fascia or periosteum
- occasional alveolar pattern
Immunohistochemistry
Immunohistochemistry stains often express MUC4 and can express EMA or smooth muscle actin. They are usually negative for keratin .
Genetics
Sclerosing epithelioid fibrosarcomas can demonstrate EWSR1-CREB3L1 gene fusions.
Radiographic features
Descriptions of imaging findings of sclerosing epithelioid fibrosarcomas are few in the literature .
Plain radiographs
There have been descriptions of punched-out osteolytic appearance with a sclerotic rim .
CT
CT findings in sclerosing epithelioid fibrosarcomas have been reported as heterogeneous soft tissue masses. In the case of osseous involvement, they have been described as osteolytic lesions with bone destruction but none or only slight periosteal reaction .
MRI
Only a few descriptions are available in the literature. Lesions might be well-circumscribed and sharply demarcated and associated with peritumoral edema or in case of osseous involvement bone marrow edema .
Signal characteristics of different single cases were reported as follows :
- T1: hypo- to isointense to muscle
- T2: mixed-signal intensity with irregular hypointense areas
- T1 C+ (Gd): heterogeneous and perilesional enhancement
Nuclear medicine
PET-CT
FDG uptake is assumed to correlate with the grade .
Radiology report
The radiological report should include a description of the following features:
- form, location and size
- tumor margins
- relation to adjacent bones and the muscular fascia
- relationship to local nerves and vessels
- relationship to other organs
Treatment and prognosis
Recurrences and metastases in sclerosing epithelioid fibrosarcomas are common and occur each in about 50% of the cases. Most common sites for metastasis are lung, pleura, bone and brain .
History and etymology
Sclerosing epithelioid fibrosarcoma was first described by a Swedish pathologist Jeanne M Meis-Kindblom in 1995 .
Differential diagnosis
Conditions which can mimic the appearance of sclerosing epithelioid fibrosarcomas include :
