Clinicopathological features of rhabdomyosarcoma with novel FET::TFCP2 and TIMP3::ALK fusion: report of two cases and literature review

Abstract

The aim of this study was to evaluate the clinicopathological features, immunophenotype, differential diagnosis, molecular genetic features and prognosis of spindle cell rhabdomyosarcoma with TFCP2 rearrangement. Methods: Two cases of spindle cell rhabdomyosarcoma with FET::TFCP2 gene fusion were included in this study. Samples were collected and evaluated through histological observation, immunohistochemistry, fluorescence in-situ hybridisation and highthroughput gene sequencing and previous findings. Results: The tumour tissues mainly comprised spindle cells and epithelioid cells, which expressed striated muscle markers, and exhibited high expression levels of CK and ALK protein markers. Molecular detection showed that the FET::TFCP2 gene was fused. A rare case with TIMP3::ALK and FUS::TFCP2 double-fusion was observed in this study. Conclusions: A case with double fusion of ALK and TFCP2 was reported in rhabdomyosarcoma for the first time in this study, which provides information on the molecular characteristic of the tumour. Spindle cell rhabdomyosarcoma with FET::TFCP2 fusion is characterised by histological, immunohistochemical and genetic changes. The tumour is aggressive, with poor prognosis and poor response to radiotherapy and chemotherapy. The efficacy of targeted therapy for ALK should be explored through more clinical studies.

Cutaneous rhabdomyosarcoma with FUS::TFCP2 fusion: A case report emphasizing early detection

“…In that case, a 54‐year‐old female patient underwent initial surgical resection of a mass, which was initially diagnosed as fibroblastic hyperplasia—a spindle cell tumor growing in fascicles with mild to moderate atypia. However, during the second occurrence, the patient presented with a clearly high‐grade tumor 11 . This highlights the importance of early detection, particularly given the potential for rapid progression.…”

“…Rare cases involving extra‐osseous locations such as soft tissue, oral mucosa, peritoneum, nasal cavity, bladder, lower back, and scalp have also been documented. The clinicopathologic details of extra‐osseous tumors in the previous reports are summarized in Table 1 1,2,6–11 …”

“…Low‐grade fibromyxoid sarcoma shows positivity for MUC4 and negativity for cytokeratin, desmin, and MyoD1 13 . In contrast, epithelioid and spindle cell rhabdomyosarcoma with FUS::TFCP2 fusion is MUC4 negative while positive for cytokeratin, desmin, and MyoD1 1–11 …”

“…Immunohistochemically, these tumors demonstrate coexpression of rhabdomyoblastic markers, keratins, and ALK 1 . While the majority of cases have been reported in the craniofacial bones, rare cases involving soft tissue, oral mucosa, peritenoum, nasal cavity, bladder, and scalp have been documented 1–11 …”

“…1 While the majority of cases have been reported in the craniofacial bones, rare cases involving soft tissue, oral mucosa, peritenoum, nasal cavity, bladder, and scalp have been documented. [1][2][3][4][5][6][7][8][9][10][11] Here, we present a case of cutaneous rhabdomyosarcoma with an initial pathological and clinical presentation that mimicked a benign process but ultimately revealed a high-grade tumor. This case underscores the importance of early detection, providing an opportunity for timely intervention and improved outcomes.…”