Definition: Low-grade fibromyxoid sarcoma is a rare, benign-appearing soft tissue neoplasm with an aggressive clinical course characterized by multiple local recurrences over several years, with ultimate spread to lung and occasionally to bone.

Differential diagnosis

 fusiform cell tumors (spindle cell tumors)

• desmoid fibromatosis (deep fibromatosis)
• leiomyosarcoma
• myofibrosarcoma
• sclerosing epithelioid fibrosarcoma
• low-grade fibrosarcoma
• classic fibrosarcoma
• inflammatory myxohyaline/myxoinflammatory fibroblastic sarcoma
• nodular fasciitis

Variants

 hyalinizing spindle cell tumor with giant rosettes (HSCT)
 deep low-grade fibromyxoid sarcoma
 superficial low-grade fibromyxoid sarcoma

• sub-cutaneous low-grade fibromyxoid sarcoma
• dermal low-grade fibromyxoid sarcoma

Cytogenetics

 t(7;16)(q33;p11) creating FUS/CREB3L2 fusion gene (#12960807#) (also found in hyalinizing spindle cell tumor with giant rosettes)

Molecular biology

 FUS/CREB3L2 fusion gene (or FUS/BBF2H7) by t(7;16)(q33;p11) (7q33 amd 11p11) (#15139001#)

References

 Mertens F, Fletcher CD, Antonescu CR, Coindre JM, Colecchia M, Domanski HA, Downs-Kelly E, Fisher C, Goldblum JR, Guillou L, Reid R, Rosai J, Sciot R, Mandahl N, Panagopoulos I. Clinicopathologic and molecular genetic characterization of low-grade fibromyxoid sarcoma, and cloning of a novel FUS/CREB3L1 fusion gene. Lab Invest. 2005 Mar;85(3):408-15. PMID: #15640831#

 Reid R, de Silva MV, Paterson L, Ryan E, Fisher C. Low-grade fibromyxoid sarcoma and hyalinizing spindle cell tumor with giant rosettes share a common t(7;16)(q34;p11) translocation. Am J Surg Pathol. 2003 Sep;27(9):1229-36. PMID: #12960807#