extraskeletal myxoid chondrosarcoma

extraskeletal myxoid chondrosarcoma

A phenotypically and genotypically distinct mesenchymal malignancy with tumour-specific fusion genes, which affects older adults and represents 2.5% of soft tissue sarcomas. ESMCS differs from the primary skeletal chondrosarcoma given the myxoid changes, and is classified as a tumour of uncertain differentiation. It arises in the deep soft tissues of the leg in 75% of cases (thigh, popliteal fossa and buttock). 80% occur in the proximal extremities and limb girdles; 20% in the trunk.

Extraskeletal myxoid chondrosarcoma
• Cellular variant without myxoid matrix;
• Classical variant;
• Dedifferentiated type;
• Epithelioid type;
• Rhabdoid type;
• Small cell type.

Imaging
Cortical erosion and buttressing.

Epidemiology
Male:female ratio, 2:1.

DiffDx
Intramuscular myxoma, myxoid liposarcoma, fibromyxoid sarcoma, myxoid embryonal rhabdomyosarcoma.
 
Differentiation
Cartilaginous, neuroendocrine, neural.

Management
Surgical excision; adjuvant chemotherapy if nodal spread or metastasis.

Prognosis
Frequent local recurrence; late metastases; 5-year, 10-year, 15-year survival, 90%, 70%, 60% respectively; continued follow-up is necessary.
References in periodicals archive ?
Identification of C11orf95-MKL2, the resulting fusion oncogene of t(11;16)(q13;p13), is useful in establishing the diagnosis of chondroid lipoma, a benign soft tissue tumor that can be mistaken for a sarcoma, especially myxoid liposarcoma or extraskeletal myxoid chondrosarcoma.
For example, although the t(11;22)(q24;q12) is characteristic of Ewing sarcoma/PNET, rearrangement of EWSR1 (22q12) is not confined to Ewing sarcoma but is also seen in most or in smaller subsets of desmoplastic small round-cell tumor, clear cell sarcoma, extraskeletal myxoid chondrosarcoma, and myxoid or round cell liposarcoma, among others.
Bulbous urethra involved in perineal extraskeletal myxoid chondrosarcoma in a child.
For example, EWSR1 is rearranged in ES/PNET, desmoplastic round cell tumor, extraskeletal myxoid chondrosarcoma, some myxoid/round cell sarcomas, and clear cell sarcoma.
3,11,12) The differential diagnostic entities of chordoma include extraskeletal myxoid chondrosarcoma, chondrosarcoma, liposarcoma, metastatic mucinous adenocarcinoma, salivary gland carcinoma (head and neck region), myoepithelial tumors, and metastatic renal cell carcinoma.
Possible diagnoses entertained included Ewing sarcoma/primitive neuroectodermal tumor, alveolar rhabdomyosarcoma, extraskeletal myxoid chondrosarcoma, epithelioid sarcoma, poorly differentiated synovial sarcoma, DSRCT, and unusual examples of leiomyoma, leiomyosarcoma, and various ovarian or myoepithelial tumors.
Of the aforementioned diagnostic considerations for the current case, alveolar rhabdomyosarcoma, extraskeletal myxoid chondrosarcoma, epithelioid sarcoma, myoepithelial tumors, and DSRCT may all demonstrate polyphenotypic immunohistochemical profiles.
We have previously shown that this break-apart FISH assay is comparably sensitive and specific to reverse transcriptase/polymerase chain reaction in detecting translocations involving the EWS locus in Ewing sarcoma/ primitive neuroectodermal tumor and DSRCT (8); however, it does not differentiate between the numerous possible translocations that may involve this locus, including fusion of EWS with various members of the ETS family of transcription factors in Ewing sarcoma/primitive neuroectodermal tumor, as well as the specific translocations of DSRCT, clear cell sarcoma of soft parts, and extraskeletal myxoid chondrosarcoma.
All 8 cases of alveolar soft part sarcoma and 7 examples of extraskeletal myxoid chondrosarcoma failed to demonstrate ECAD or NCAD expression.
Extraskeletal myxoid chondrosarcoma and conventional chondrosarcoma of bone usually can be distinguished from primary or metastatic chordoma if clinical, radiologic, and histomorphologic features are taken into account.
Caution must be exercised in the interpretation of lipoblast- or chondroblast-like cells in chondromyxoid matrix because similar findings may be seen in myxoid liposarcoma, extraskeletal myxoid chondrosarcoma, extraskeletal chondroma, and hibernoma.
The extraskeletal myxoid chondrosarcoma is also a malignant deep soft tissue mass, in which fibrocartilage is not a feature.