RAF1-rearranged Spindle Cell Mesenchymal Tumor With Calcification and Heterotopic Ossification: A Case Report and Review of Literature.

We report an exceptional case of a spindle cell mesenchymal tumor with S100 and CD34 co-reactivity, which harbored a SLMAP::RAF1 fusion. To the best of our knowledge, this is the second case of a spindle cell mesenchymal tumor with S100 and CD34 co-reactivity with this specific fusion. Remarkable is the presence of calcification and heterotopic ossification in the center of our lesion, a feature that, to our knowledge, has not been described yet in RAF1-rearranged spindle cell mesenchymal tumors.

[1]  Jessica L. Davis,et al.  Histologic characterization of paediatric mesenchymal neoplasms treated with kinase‐targeted therapy , 2022, Histopathology.

[2]  T. Shek,et al.  Novel MAP4::RAF1 Fusion in a Primary Bone Sarcoma: Expanding the spectrum of RAF1 Fusion Sarcoma , 2022, International journal of surgical pathology.

[3]  Jessica L. Davis,et al.  Mesenchymal neoplasms with NTRK and other kinase gene alterations , 2021, Histopathology.

[4]  Qingyu Wang,et al.  RAF1-rearranged spindle cell tumour: report of two additional cases with identification of a novel FMR1-RAF1 fusion , 2021, Virchows Archiv.

[5]  C. Lebbé,et al.  Spindle cell tumor with CD34 and S100 co‐expression and distinctive stromal and perivascular hyalinization showing EML4‐ALK fusion , 2020, Journal of cutaneous pathology.

[6]  Jessica L. Davis,et al.  Infantile fibrosarcoma with a novel RAF1 rearrangement: The contemporary challenge of reconciling classic morphology with novel molecular genetics , 2020 .

[7]  J. Smadbeck,et al.  Biology and grading of pleomorphic xanthoastrocytoma—what have we learned about it? , 2020, Brain pathology.

[8]  C. Antonescu.  Emerging soft tissue tumors with kinase fusions: An overview of the recent literature with an emphasis on diagnostic criteria , 2020, Genes, chromosomes & cancer.

[9]  R. Alaggio,et al.  Novel PPP1CB‐ALK fusion in spindle cell tumor defined by S100 and CD34 coexpression and distinctive stromal and perivascular hyalinization , 2020, Genes, chromosomes & cancer.

[10]  J. Ross,et al.  Melanomas with activating RAF1 fusions: clinical, histopathologic, and molecular profiles , 2020, Modern Pathology.

[11]  K. Fritchie,et al.  Calcification and ossification in conventional schwannoma: A clinicopathologic study of 32 cases , 2019, Neuropathology : official journal of the Japanese Society of Neuropathology.

[12]  M. Berger,et al.  The genetic landscape of anaplastic pleomorphic xanthoastrocytoma , 2018, Brain pathology.

[13]  T. Richardson,et al.  Spinal Pleomorphic Xanthoastrocytoma With a QKI-RAF1 Fusion , 2018, Journal of neuropathology and experimental neurology.

[14]  A. Brohl,et al.  Identification of a novel MTAP-RAF1 fusion in a soft tissue sarcoma , 2018, Diagnostic Pathology.

[15]  C. Antonescu,et al.  A novel group of spindle cell tumors defined by S100 and CD34 co‐expression shows recurrent fusions involving RAF1, BRAF, and NTRK1/2 genes , 2018, Genes, chromosomes & cancer.

[16]  A. Resnick,et al.  CRAF gene fusions in pediatric low-grade gliomas define a distinct drug response based on dimerization profiles , 2017, Oncogene.

[17]  Nicolas Stransky,et al.  The landscape of kinase fusions in cancer , 2014, Nature Communications.