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Recurrent RET gene fusions in paediatric spindle mesenchymal neoplasms*
Author(s) -
Davis Jessica L,
Vargas Sara O,
Rudzinski Erin R,
López Marti Jessica M,
Janeway Katherine,
Forrest Suzanne,
Winsnes Katrina,
Pinto Navin,
Yang Sung E,
VanSandt Mandy,
Boyd Theonia K,
Corless Christopher L,
Liu Yajuan J,
Surrey Lea F,
Harris Marian H,
Church Alanna,
AlIbraheemi Alyaa
Publication year - 2020
Publication title -
histopathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.626
H-Index - 124
eISSN - 1365-2559
pISSN - 0309-0167
DOI - 10.1111/his.14082
Subject(s) - fibrosarcoma , pathology , cd34 , pathological , sarcoma , medicine , metastasis , mesenchymal stem cell , biology , cancer , genetics , stem cell
Aims The classification of paediatric spindle mesenchymal tumours is evolving, and the spectrum of so‐called ‘infantile fibrosarcoma’ has expanded to include tumours with NTRK , BRAF and MET gene fusions. RET ‐rearranged paediatric spindle cell neoplasms are an emerging group; there is sparse literature on their clinical, pathological and genetic features, and their nosological place in the canon of soft tissue tumours is uncertain. In this study, we report five RET ‐rearranged paediatric spindle cell tumours with fusion partners MYH10 , KIAA1217 and CLIP2 . Methods and results The tumours occurred in the pelvic region, paraspinal region, kidney and subcutaneous tissue of hand and abdomen. The patients’ ages ranged from 6 months to 13 years (median 1 year). The tumours were composed of monomorphic spindle cells arranged in a fascicular pattern. Lesional cells had minimally atypical ovoid or tapered nuclei and pale cytoplasm with indistinct borders. Necrosis was not identified. Mitoses numbered three to 12 per 10 high‐power field. Cases showed inconsistent and variable expression of S100, CD34 and SMA. Clinical behaviour ranged from small lesions potentially cured by simple resection to large lesions exhibiting metastasis, but responsive to kinase inhibitor therapy. Conclusions Our findings help to define RET ‐rearranged spindle cell tumours. Although it is likely that these tumours comprise part of the morphological and clinical spectrum of infantile fibrosarcoma (IFS), identification of RET gene alteration is important for its unique therapeutic implications.