Sarcoma with MGA::NUTM1 fusion: a report of three cases and literature review.

AIMS: NUTM1-rearranged sarcoma is an emerging entity that differs from NUT carcinoma at the molecular level, with most of the former tumours harbouring fusions involving genes in the MYC-associated factor X dimerization (MAD) transcription family (MXD1, MXD4, MXI1 [or MXD2], and MGA). MGA::NUTM1 is one of the most recently described novel gene fusions associated with NUTM1-rearranged sarcoma. Herein we describe the clinicopathologic features of three sarcomas with an MGA::NUTM1 fusion. METHODS AND RESULTS: The three study patients were male, with an age range of 10-28 years. The tumour sites were deep soft tissue of the thigh, the chest wall, and the pelvis. All three tumours were aggressive, with multiple recurrences and metastases. Histologically, the tumours were composed of monotonous spindle, round, or epithelioid cells in variably hyalinized stroma and prominent aggregates of amianthoid fibre-like collagen or collagen rosettes. Mitotic activity was relatively low (5-12 mitotic figures per 10 hhpf). All tumours tested expressed NUT, with one tumour having S100 protein expression and two tumours having CD99 and CD56 expression. The genetic breakpoints were MGA exon 21, MGA exon 22, and NUTM1 exon 3. CONCLUSION: MGA::NUTM1 sarcoma often exhibits hyalinized stroma with amianthoid fibre-like collagen or collagen rosettes in the presence of monotonous round, epithelioid, or spindle cell morphology. NUT immunohistochemistry and molecular testing can help confirm the diagnosis.

Detecting disease-defining gene fusions in unclassified round cell sarcomas using anchored multiplex PCR/targeted RNA next-generation sequencing-Molecular and clinicopathological characterization of 16 cases.

Detection of disease-defining gene fusions in sarcoma has led to refining their classification, as well as to discover several new entities. The advent of anchored multiplex PCR/targeted RNA next-generation sequencing (AMP/RNA-seq) has allowed for the development of scalable platforms that can simultaneously examine multiple fusion transcripts without prior knowledge of specific fusion partners.In this study, we assess the utility of a FusionPlex sarcoma panel analysis by AMP/RNA-seq to detect disease-defining gene fusions in 16 cases of undifferentiated round cell sarcoma in which prior diagnostic work-up could not establish a definitive diagnosis. The clinical and pathologic features of these cases were correlated with the molecular findings. Validation of the method using 41 cases with known diagnoses showed analytic sensitivity and specificity of 98% and 100%, respectively. Of the 16 cases of undifferentiated round cell sarcoma, gene fusions were found in 9 (56%). These included three cases with CIC-DUX4 fusion, two cases with BCOR-CCNB3, and four single cases with CIC-NUTM2A, HEY1-NCOA2, EWSR1-NFATC2, and NUT-MGA1 fusions. Overall, despite some degree of morphologic overlap, all fusion-positive cases had distinct morphologic features, which can be helpful for their histologic classification. We also describe the first adult case of MGA-NUTM1 fusion sarcoma, as well as cartilaginous differentiation in a BCOR-CCNB3 fusion sarcoma, which has not been previously reported. Our study demonstrated that FusionPlex sarcoma panel analysis, in the appropriate morphologic context, is a sensitive and precise ancillary method for the detection of disease-defining gene fusions in undifferentiated round cell sarcomas, aiding in their definitive classification.

Spindle cell sarcoma of the chest wall: a pediatric case report.

Chest wall sarcomas are reported to be infrequent among thoracic tumors. The spindle cell subtype makes up a small percentage of this group. These tumors can be asymptomatic or cause symptoms of chest pain and shortness of breath due to the mass effect, which can lead to a delay in diagnosis. A 10-year-old female with a persistent cough, shortness of breath on exertion, and left-sided chest pain presented to the ED. Imaging indicated a chest wall mass filling the left hemithorax with a rightward mediastinal shift. During surgical resection, two tumors were removed, with resection of parts of the latissimus dorsi and serratus anterior. A diagnosis of MGA:NUTM1 spindle cell sarcoma was made pathologically. The patient was successfully treated with surgery and adjuvant chemoradiotherapy. We hope to add to our academic knowledge by presenting the presentation and treatment of SCS in a pediatric patient.

Primary Spindle Cell Sarcoma of the Lung with MGA::NUTM1 Fusion: An Extremely Rare Case of a Potentially Emerging Entity and Review of the Literature.

Originally described in a rare subset of poorly differentiated squamous cell carcinomas termed NUT carcinomas, NUTM1 rearrangements are now known to characterize a wide spectrum of neoplasms including sarcomas, poromas/porocarcinomas, unclassified adnexal carcinomas and pediatric acute lymphoblastic leukemia. The advent of next-generation sequencing (NGS) has led to the identification of a multitude of novel fusion partners in addition to BRD4, which was initially reported in the majority of NUT carcinomas. NUTM1-rearranged sarcomas usually harbor fusions with the MAD gene family (MXD1, MXD4, MGA) and present as spindle cell proliferations in diverse locations in patients of all ages. Herein, we present a very rare case of spindle cell sarcoma of the lung, which harbored a NUTM1::MGA fusion and offer a comprehensive update of the recent data.