Low-grade myofibroblastic sarcoma
Low-grade myofibroblastic sarcomas are locally aggressive rarely metastasizing fibroblastic tumors.
Terminology
Another acceptable term for low-grade myofibroblastic sarcoma is myofibrosarcoma .
Epidemiology
Low-grade myofibroblastic sarcomas most commonly occur in adults in the 4 and 5 decade of life with a minor male predominance and are rarely found in children .
Clinical presentation
Typical manifestation is a painless growing mass, rarely associated with pain or symptoms related to organ displacement .
Pathology
Low-grade myofibroblastic sarcomas are aggressive tumors with diffusely infiltrative growth characterized by fascicles of eosinophilic spindle cells with at least focal nuclear atypia .
Location
Low-grade myofibroblastic sarcomas feature a wide anatomic distribution. Common locations include the extremities and the head and neck region including the tongue and oral cavity. The skin and gastrointestinal tract are rarely affected .
Macroscopic appearance
Macroscopically low-grade myofibroblastic sarcomas are firm, lobulated tumors with a pale appearance. Their margins are usually infiltrative and less commonly well-circumscribed .
Microscopic appearance
The microscopic spectrum of low-grade myofibroblastic sarcomas includes the following :
- diffuse infiltrative growth pattern
- sometimes between skeletal muscle fibers
- composed of spindle tumor cells in cellular fascicles with pale eosinophilic cytoplasm
- at least focally nuclear atypia
- sometimes collagenous hyalinized background
Immunohistochemistry
Immunohistochemistry stains might express smooth muscle actin and/or desmin .
Radiographic features
There are only varying descriptions of imaging appearances in low-grade myofibroblastic sarcomas. They seem to appear as unspecific soft tissue mass and vary significantly also with the site of the tumor .
CT
Some low-grade myofibroblastic sarcomas might show calcifications or ossification. Lesions with osseous involvement have been described as osteolytic, destructive masses .
MRI
Imaging findings have been described as diverse and seem to vary with the site of involvement .
Signal characteristics were described as follows:
- T1: mostly hypo- to isointense to muscle
- T2: heterogeneous high signal intensity
- T1 C+ (Gd): ranges from homogenous to heterogeneous predominantly peripheral enhancement
Radiology report
The radiological report should include a description of the following:
- form, location and size
- tumor margins
- relation to adjacent bones and muscular fasciae
- relationship to local nerves and vessels
- relationship to other organs
Treatment and prognosis
Similar to other mesenchymal tumors, surgery is the mainstay. Local recurrence is common often happening after a prolonged time. Metastases occur rarely .
History and etymology
Low-grade myofibroblastic sarcoma or was first described by Mentzel as a distinctive entity in 1998 .
Differential diagnosis
Conditions which can mimic the presentation and/or the appearance of low-grade myofibroblastic sarcomas include :
