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 1, and are difficult to distinguish from other pleomorphic sarcomas such as malignant fibrous histiocytomas 2.
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.
Can reveal the following to varying proportions:
- myoglobin: common
- skeletal muscle myogenin (myf4)
- fast skeletal muscle myosin
- muscle-specific actin
- smooth muscle actin (SMA)
- muscle specific myogenin (myf3)
They typically occur in the limbs, with a predilection for the thigh 2.
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 1.
Treatment and prognosis
It is considered a high-grade sarcoma, with an aggressive clinical course 3.
- 1. Schepper AM, Parizel PM, Vanhoenacker FM. Imaging of soft tissue tumors. Springer Verlag. (2006) ISBN:3540248099. Read it at Google Books - Find it at Amazon
- 2. Kransdorf MJ, Murphey MD. Imaging of soft tissue tumors. Lippincott Williams & Wilkins. (2006) ISBN:0781747716. Read it at Google Books - Find it at Amazon
- 3. Furlong MA, Mentzel T, Fanburg-Smith JC. Pleomorphic rhabdomyosarcoma in adults: a clinicopathologic study of 38 cases with emphasis on morphologic variants and recent skeletal muscle-specific markers. (2001) Modern pathology : an official journal of the United States and Canadian Academy of Pathology, Inc. 14 (6): 595-603. doi:10.1038/modpathol.3880357 - Pubmed
- 4. Furlong MA, Fanburg-Smith JC. Pleomorphic rhabdomyosarcoma in children: four cases in the pediatric age group. (2001) Annals of diagnostic pathology. 5 (4): 199-206. doi:10.1053/adpa.2001.26970 - Pubmed
- 5. Gaffney EF, Dervan PA, Fletcher CD. Pleomorphic rhabdomyosarcoma in adulthood. Analysis of 11 cases with definition of diagnostic criteria. (1993) The American journal of surgical pathology. 17 (6): 601-9. Pubmed