pleomorphic rhabdomyosarcoma
Pleomorphic rhabdomyosarcoma is a type of rhabdomyosarcoma, and is the least common, accounting for only 5% of all rhabdomyosarcomas. Unlike embryonal and pleomorphic types, these tumors occur in adults over the age of 40 years , and are difficult to distinguish from other pleomorphic sarcomas such as malignant fibrous histiocytomas .
Pathology
Some publications divide into 3 specific types
- classic: predominantly atypical pleomorphic polygonal rhabdomyoblasts (PRMB) in sheets
- round cell: clusters of PRMB throughout the tumor with a background of slightly atypical, medium-sized, round, blue RMB
- spindle cell: scattered PRMB in a predominance of atypical spindled RMB arranged in a storiform growth pattern.
Immunohistochemistry
Can reveal the following to varying proportions:
- myoglobin: common
- MyoD1
- skeletal muscle myogenin (myf4)
- fast skeletal muscle myosin
- desmin
- muscle-specific actin
- smooth muscle actin (SMA)
- muscle specific myogenin (myf3)
Location
They typically occur in the limbs, with a predilection for the thigh .
Radiographic features
The features are non-specific (see radiographic features in the parent article: rhabdomyosarcoma), although in general pleomorphic rhabdomyosarcomas have multiple areas of necrosis. In some instances, these areas are surrounded by pronounced ring-like enhancement .
Treatment and prognosis
It is considered a high-grade sarcoma, with an aggressive clinical course .
Siehe auch:
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Assoziationen und Differentialdiagnosen zu pleomorphic rhabdomyosarcoma:
