Genetic analyses of undifferentiated small round cell sarcoma identifies a novel sarcoma subtype with a recurrent CRTC1-SS18 gene fusion.

In recent years, undifferentiated small round cell sarcomas (USRCSs) have been divided into a variety of new, rare, sarcoma subtypes, including the group of Ewing-like sarcomas, which have the morphological appearance of Ewing sarcomas, but carry CIC-DUX4, BCOR-CCNB3 and other gene fusions different from the classic EWSR1-ETS gene fusion. Using high-throughput RNA-sequencing (RNA-seq) analyses, we identified a novel recurrent gene fusion, CRTC1-SS18, in two cases of USRCS that lacked any known translocation. RNA-seq results were confirmed by reverse transcription polymerase chain reaction, long-range polymerase chain reaction, and fluorescence in situ hybridization.

YAP1-TFE3 epithelioid hemangioendothelioma: a case without vasoformation and a new transcript variant.

Epithelioid hemangioendothelioma is a rare vascular tumor of borderline malignancy characterized by recurrent WWTR1-CAMTA1 gene fusions in approximately 90 % of cases. In addition, a recurrent YAP1-TFE3 gene fusion has been identified in WWTR1-CAMTA1 negative epithelioid hemangioendotheliomas. This subset has been reported as having a distinct morphology with more obvious vasoformation, voluminous eosinophilic cytoplasm, and TFE3 positivity on immunohistochemistry.

BCOR-CCNB3 (Ewing-like) sarcoma: a clinicopathologic analysis of 10 cases, in comparison with conventional Ewing sarcoma.

BCOR-CCNB3 fusion transcripts resulting from an X-chromosomal paracentric inversion were recently identified in a series of unclassifiable soft tissue and bone sarcomas with Ewing sarcoma-like morphology. The morphologic and clinical features of these sarcomas are, as yet, not well characterized. Here we describe the clinicopathologic features of 10 cases of BCOR-CCNB3 sarcoma and compare their clinical course with typical Ewing sarcoma.

Molecular pathology of bone tumours: diagnostic implications.

Alongside histomorphology and immunohistochemistry, molecular pathology is now established as one of the cornerstones in the tissue diagnosis of bone tumours. We describe the principal molecular pathological techniques employed, and each of the bone tumour entities where their identified characteristic molecular pathological changes can be detected to support and confirm the suspected histological diagnosis. Tumours discussed include fibrous dysplasia, classical and subtype osteosarcomas, central and surface cartilaginous tumours, Ewing's sarcoma, vascular tumours, aneurysmal bone cyst, chordoma, myoepithelioma, and angiomatoid fibrous histiocytoma.