Myxoid pleomorphic liposarcoma
Myxoid pleomorphic liposarcomas are extremely rare aggressive malignant neoplasms arising from adipocytic tissues characterized by a mixture of pleomorphic and myxoid features and the absence of genetic fusions and amplifications seen of well-differentiated liposarcoma and other lines of differentiation.
Myxoid pleomorphic sarcomas are extremely rare and affect children and young adults up to the age of 30 years on most occasions. Women are more frequently afflicted 1,2.
There have been associations of myxoid pleomorphic liposarcoma and Li Fraumeni syndrome 3-5.
The most common presentation is that of a large soft tissue mass 1.
Myxoid pleomorphic liposarcomas are highly malignant neoplasms characterized by an admixture of myxoid liposarcoma-like zones and densely pleomorphic cellular areas with pleomorphic lipoblasts as seen in pleomorphic liposarcoma. Since 2020 they are considered a separate entity in the WHO classification of soft tissue tumors 1,2.
The most frequent site of involvement by myxoid pleomorphic liposarcoma is the mediastinum. There are also reports of the thigh, head and neck, perineum abdomen and back 1.
Myxoid pleomorphic liposarcomas are not encapsulated and are characterized by ill-defined margins 1.
The microscopic appearance of myxoid pleomorphic liposarcomas is characterized by a mixture of myxoid and pleomorphic features and includes the following 1,2:
- infiltrative margins
- abundant myxoid matrix with plexiform vascular patterns
- scattered lipoblasts
- pleomorphic spindle cells
- pleomorphic lipoblasts
- increased mitotic activity and atypical mitosis
- occasional necrosis
Myxoid pleomorphic liposarcomas do not feature specific immunotypes 1.
Descriptions about imaging characteristics dedicated to myxoid pleomorphic liposarcomas are scarce. They probably look like heterogeneous soft tissue masses with myxoid components which are characterized by high water content.
The radiological report should include a description of the following:
- form, location and size
- tumor margins
- amount of solid and fatty components
- relation to other organs structures
Treatment and prognosis
Myxoid pleomorphic liposarcomas are characterized by a high local recurrence, distant metastases and a poor survival rate 1.
Conditions which can mimic the clinical or radiological presentation of myxoid pleomorphic sarcoma are any fast-growing soft tissue tumors and include 1:
- myxoid liposarcoma
- pleomorphic liposarcoma
- dedifferentiated liposarcoma
- 1. W.H.O. Classification WHO Classification of Tumours Editorial Board, Who Classification of Tumours Editorial. Soft Tissue and Bone Tumours. (2020) ISBN: 9789283245025
- 2. Sbaraglia M, Bellan E, Dei Tos AP. The 2020 WHO Classification of Soft Tissue Tumours: news and perspectives. (2020) Pathologica. doi:10.32074/1591-951X-213 - Pubmed
- 3. Francom CR, Leoniak SM, Lovell MA, Herrmann BW. Head and neck pleomorphic myxoid liposarcoma in a child with Li-Fraumeni syndrome. (2019) International journal of pediatric otorhinolaryngology. 123: 191-194. doi:10.1016/j.ijporl.2019.05.016 - Pubmed
- 4. Zare SY, Leivo M, Fadare O. Recurrent Pleomorphic Myxoid Liposarcoma in a Patient With Li-Fraumeni Syndrome. (2020) International journal of surgical pathology. 28 (2): 225-228. doi:10.1177/1066896919878804 - Pubmed
- 5. Sinclair TJ, Thorson CM, Alvarez E, Tan S, Spunt SL, Chao SD. Pleomorphic myxoid liposarcoma in an adolescent with Li-Fraumeni syndrome. (2017) Pediatric surgery international. 33 (5): 631-635. doi:10.1007/s00383-017-4063-x - Pubmed
- 6. Murphey MD, Arcara LK, Fanburg-Smith J. From the archives of the AFIP: imaging of musculoskeletal liposarcoma with radiologic-pathologic correlation. (2005) Radiographics : a review publication of the Radiological Society of North America, Inc. 25 (5): 1371-95. doi:10.1148/rg.255055106 - Pubmed