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Intimal sarcoma is one of the most common and well-known primary malignant neoplasms of the aorta and heart. The authors reviewed cases of intimal sarcoma from histological, immunohistochemical and genetic perspectives. Twenty cases of intimal sarcoma were retrieved. Immunohistochemistry and FISH of MDM2 and PDGFRA genes were performed. All 20 tumours were composed of spindle-shaped, stellate, oval or polygonal tumour cells with irregular hyperchromatic nuclei arranged in a haphazard pattern, accompanied by nuclear pleomorphism and frequent mitotic figures. Other histological findings were as follows: abnormal mitosis in 10 cases (50%), necrosis in 15 cases (75%), myxoid stroma in 12 cases (60%), cartilaginous formation in 1 case (5%), haemorrhage in 12 cases (60%) and fibrinous deposition in 14 cases (70%). The tumours were positive for MDM2 in 16 cases (80%), ERG in 4 cases (20%), alpha-smooth muscle actin in 6 cases (30%), desmin in 5 cases (25%) and AE1/AE3 in 4 cases (20%). Immunohistochemical positivity was focal in each case. Loss of H3K27me3 expression was noted in 2 cases (10%). MDM2 and PDGFRA gene amplifications were detected in 11 cases (55%) and 1 case (5%), respectively. Fisher's exact test revealed a significant correlation between MDM2 gene amplification and myxoid stroma (p = 0.0194). No parameters showed any association with the anatomical location of the tumours. It was suggested that myxoid histology of intimal sarcoma may be associated with MDM2 gene amplification and that intimal sarcoma may be divided into myxoid and non-myxoid types., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: Undifferentiated pleomorphic sarcoma (UPS) is a sarcoma with a poor prognosis. A clinical trial, SARC028, revealed that treatment with anti-PD-1 drugs was effective against UPS. Studies have reported that UPS expresses PD-L1, sometimes strongly (≥ 50%). However, the mechanism of PD-L1 expression in UPS has remained unclear. CKLF-like MARVEL transmembrane domain containing 6 (CMTM6) was identified as a novel regulator of PD-L1 expression. The positive relationship between PD-L1 and CMTM6 has been reported in several studies. The aim of this study was thus to examine CMTM6 expression in UPS and evaluate the relationship between PD-L1 and CMTM6 in this disease., Materials and Methods: Fifty-one primary UPS samples were subjected to CMTM6 and PD-L1 immunostaining. CMTM6 expression was assessed using proportion and intensity scores. CMTM6 gene copy number was also evaluated using a real-time PCR-based copy number assay. We also analyzed the mRNA expression and copy number variation of PD-L1 and CMTM6 in The Cancer Genome Atlas (TCGA) data., Results: TCGA data indicated that the mRNAs encoded by genes located around 3p22 were coexpressed with CMTM6 mRNA in UPS. Both proportion and intensity scores of CMTM6 positively correlated with strong PD-L1 expression (≥ 50%) (both p = 0.023). CMTM6 copy number gain increased CMTM6 expression. Patients with UPS with a high CMTM6 intensity score had a worse prognosis for overall survival., Conclusions: UPS showed variation in CMTM6 copy number and CMTM6 expression. CMTM6 expression was significantly correlated with PD-L1 expression, especially with strong PD-L1 expression.