Osteosarcomatous Divergence in Dedifferentiated Liposarcoma Presenting as a Colonic Mass

Abstract

Dedifferentiated liposarcomas most commonly arise in the retroperitoneum, accounting for 10% of liposarcomas. Heterologous differentiation occurs in 5-10% of dedifferentiated liposarcomas; however, divergent osteosarcomatous differentiation is rare. We report a rare case of initial presentation of dedifferentiated liposarcoma with osteosarcomatous component as a colonic mass in a 72-year-old man. The tumor is mainly composed of bony trabeculae with intervening highly atypical cells and adjacent high-grade mesenchymal nonlipogenic tumor, as well as areas of well-differentiated liposarcoma. Immunohistochemical studies showed diffuse positivity for SATB2 in the atypical cells and fluorescence in situ hybridization revealed high-level amplification of MDM2 gene, supporting the diagnosis of well-differentiated and dedifferentiated liposarcoma with heterologous osteosarcomatous differentiation.

Retroperitoneal dedifferentiated liposarcoma with rare heterologous low-grade osteosarcoma: A case report

“…The most common dedifferentiated component is undifferentiated pleomorphic sarcoma (previously called malignant fibrous histiocytoma) or fibrosarcoma. Divergent differentiation of DDLs, including the myogenic, angio- sarcomatous, and/or osteochondromatous components, are rare and have been reported in 5%-10% of DDLs [ [6] , [7] , [8] – 9 ].…”

Multifocal Giant Retroperitoneal Dedifferentiated Liposarcoma with dual heterologous dedifferentiation– a diagnostic and therapeutic challenge

“…[4] The presence of fat components in radiology imaging findings can be helpful in the diagnosis of liposarcoma. [5] When the nonlipomatous areas exceed>2cm, it suggests the possibility of dedifferentiation. [4] The documented mean size of the DDLs is 17.5cm while here the tumor was a giant liposarcoma.…”

“…[6][7][8][9][10] Inadequately sampled specimens, therefore, might lead to missing these areas and thereby under-diagnosing DDL. [5] Irrespective of the maturity and the morphological type of bone tissue formed in DDL, it is usually neoplastic. It is a consequence of osteogenic differentiation in tumor cells.…”

“…The degree of atypia may be minimal to severe and may show heterotopic bone tissue to high-grade osteosarcoma. [5] It is also required to search for the lipoblasts with the mature adipose tissue and differentiate the former from its mimics. In this case, the widespread presence of surrounding, greasy areas with features of welldifferentiated liposarcoma made us consider the same as a primary diagnosis.…”

“…Also, it is very important to note that DDL is far more frequent as compared to extraskeletal osteosarcoma. [5] Dedifferentiation has been recorded in about 10% of well-differentiated liposarcomas. [11] Chondrosarcomas and liposarcomas frequently showcase dedifferentiation into aberrant elements.…”