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, Al-Ibraheemi Alyaa
Department of Pathology, Oregon Health and Science University, Portland, OR, USA.
Department of Pathology, Boston Children's Hospital, Boston, MA, USA.
Histopathology. 2020 Jun;76(7):1032-1041. doi: 10.1111/his.14082. Epub 2020 May 15.
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.
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.
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.
小儿梭形间充质肿瘤的分类正在不断发展，所谓的“婴儿型纤维肉瘤”的范围已经扩大，包括具有NTRK、BRAF和MET基因融合的肿瘤。RET重排的小儿梭形细胞肿瘤是一个新兴的肿瘤群体；关于其临床、病理和基因特征的文献稀少，其在软组织肿瘤分类中的地位尚不确定。在本研究中，我们报告了5例RET重排的小儿梭形细胞肿瘤，其融合伴侣为MYH10、KIAA1217和CLIP2。
肿瘤发生于盆腔、脊柱旁、肾脏以及手部和腹部的皮下组织。患者年龄为6个月至13岁（中位年龄1岁）。肿瘤由呈束状排列的单形性梭形细胞组成。病变细胞具有轻度异型的卵圆形或锥形核，胞质淡染，边界不清。未发现坏死。每10个高倍视野中有3至12个核分裂象。病例显示S100、CD34和SMA的表达不一致且多变。临床行为从通过简单切除可能治愈的小病变到表现出转移但对激酶抑制剂治疗有反应的大病变不等。
我们的研究结果有助于明确RET重排的梭形细胞肿瘤。虽然这些肿瘤可能是婴儿型纤维肉瘤（IFS）形态和临床谱的一部分，但RET基因改变的鉴定因其独特的治疗意义而很重要。
