Low-grade fibromyxoid sarcoma: Clinical, morphologic and genetic features

Area of Science:

• Soft tissue pathology
• Oncology
• Molecular genetics

Background:

• Low-grade fibromyxoid sarcoma (LGFMS) is a spindle cell neoplasm often found in deep soft tissues.
• LGFMS is frequently associated with specific genetic translocations, including FUS-CREB3L2, FUS-CREB3L1, and EWSR1-CREB3L1.
• Sclerosing epithelioid fibrosarcoma (SEF) is a related fibroblastic neoplasm with overlapping features and genetic alterations.

Purpose of the Study:

• To review the distinct morphological and immunohistochemical features of LGFMS and SEF.
• To discuss the genetic and molecular underpinnings of these tumors, including common fusion genes.
• To highlight the importance of accurate differential diagnosis for optimal patient management.

Main Methods:

• Review of literature on LGFMS and SEF.
• Analysis of morphological characteristics and immunohistochemical profiles.
• Examination of genetic and molecular findings, including specific translocations and fusion transcripts.

Main Results:

• LGFMS typically presents as bland spindle cells with myxoid and fibrous areas, consistently expressing MUC4.
• SEF shows epithelioid cells in sclerotic stroma, with some cases exhibiting LGFMS-like areas and FUS-CREB3L2 fusions.
• Both tumor types share specific genetic rearrangements and MUC4 expression in a significant subset of SEF cases.

Conclusions:

• Accurate diagnosis of LGFMS and SEF is crucial due to their potential for recurrence and metastasis.
• Understanding the shared and distinct molecular features aids in differential diagnosis.
• Surgical resection with clear margins is the primary treatment modality for these tumors.