Emerging mesenchymal tumour types and biases in the era of ubiquitous sequencing

Abstract

New tumour types are being described at increasing frequency, and most new tumour types are now identified via retrospective review of next-generation sequencing data. This contrasts with the traditional, morphology-based method of identifying new tumour types, and while the sequencing-based approach has accelerated progress in the field, it has also introduced novel and under-recognised biases. Here, we discuss tumour types identified based on morphology, including superficial CD34-positive fibroblastic tumour, pseudoendocrine sarcoma and cutaneous clear cell tumour with melanocytic differentiation andACTIN::MITFfusion. We also describe tumour types identified primarily by next-generation sequencing, including epithelioid and spindle cell rhabdomyosarcoma, round cell neoplasms withEWSR1::PATZ1fusion, cutaneous melanocytic tumour withCRTC1::TRIM11fusion, clear cell tumour with melanocytic differentiation andMITF::CREMfusion andGLI1-altered mesenchymal neoplasms, including nested glomoid neoplasm.