High-Grade Sarcomatous Transformation of Hybrid Hemosiderotic Fibrolipomatous Tumor-Myxoinflammatory Fibroblastic Sarcoma with Novel ADAMTS12::TERT Gene Fusion

This is the authors' abstract. We don't add key points for this paper.

Hemosiderotic fibrolipomatous tumor (HFLT) and myxoinflammatory fibroblastic sarcoma (MIFS) are rare, locally aggressive soft tissue tumors with a predilection for distal extremities of middle-aged adults. Hybrid tumors (HFLT-MIFS) demonstrate overlapping features of both and share recurrent translocation (1;10) (p22; q24). We describe a tumor with high-grade sarcomatous transformation of a hybrid HFLT-MIFS, with a novel ADAMTS12::TERT gene fusion, presenting as a right foot soft tissue mass in an 85-year-old woman. Histologically, the tumor showed a high-grade sarcoma with areas of hybrid HFLT-MIFS in subsequent resection. The patient was treated surgically with a below-knee amputation and interval radiation therapy. On RNA-based next-generation sequencing, the tumor harbored a novel ADAMTS12::TERT gene fusion. In addition to reporting a novel gene fusion in a rare example of hybrid HFLT-MIFS with high-grade sarcomatous transformation, we also discuss relevant morphological features of sarcomatous HFLT and provide a brief review of reported neoplasms with TERT gene fusions.