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Sarcomas are rare mesenchymal tumors with a broad histological spectrum, but they can be divided into two groups based on molecular pathology: sarcomas with simple or complex ge-nomics. Tumors with complex genomics can have aneuploidy and copy number gains and losses, which hampers the detection of early, initiating events in tumorigenesis. Often, no benign precur-sors are known, which is why good models are essential. The mesenchymal stem cell (MSC) is the presumed cell of origin of sarcoma. In this study, MSCs of murine and canine origin are used as a model to identify driver events for sarcomas with complex genomic alterations as they transform spontaneously after long‐term culture. All transformed murine but not canine MSCs formed sarcomas after subcutaneous injection in mice. Using whole genome sequencing, spontaneously transformed murine and canine MSCs displayed a complex karyotype with aneuploidy, point mutations, structural variants, inter‐chromosomal translocations, and copy number gains and losses. Cross-species analysis revealed that point mutations in Tp53/Trp53 are common in transformed murine and canine MSCs. Murine MSCs with a cre‐recombinase induced deletion of exon 2‐10 of Trp53 transformed earlier compared to wild‐type murine MSCs, confirming the contribution of loss of p53 to spontaneous transformation. Our comparative approach using transformed murine and canine MSCs points to a crucial role for p53 loss in the formation of sarcomas with complex genomics.

Undifferentiated pleomorphic sarcoma is a common soft tissue sarcoma. Unfortunately, any attempt to describe the line of differentiation fails. It represents a final common pathway in tumors that undergoes progression towards dedifferentiation. We report a man with an undifferentiated pleomorphic sarcoma presenting as an exophytic pedunculated tumor of the left scapula. Histopathology analysis revealed spindle-shaped cells with great pleomorphism and numerous mitoses. Immunohistochemistry showed diffuse expression of vimentin. Wide local excision was performed after an oncology consultation. After two-years of follow-up, the patient has shown no evidence of recurrence or metastases.

We are going to present a case of malignant fibrous histiocytoma in the right atrium, which is a very rare entity. The patient had a right atrial mass, which prolapsed through the tricuspid valve into the right ventricle, causing functional tricuspid valve stenosis. The tumor was completely resected and the patient had an uneventful postoperative period. Histopathological examination reported malignant fibrous histiocytoma. The patient presented to the emergency department five weeks after discharge with dyspnea and palpitation. Echocardiography and magnetic resonance imaging revealed recurrent right atrial tumor mass. His clinical status has worsened, with syncope and acute renal failure. On the repeated echocardiography, suspected tumor recurrence was observed in left atrium, which probably caused systemic embolization. Considering the aggressive nature of the tumor and systemic involvement, our Heart Council decided to provide palliative treatment by nonsurgical management. His status deteriorated for the next few days and the patient succumbed to a cardiac arrest on the 4th day.

Atypical fibroxanthoma (AFX) is a rare cutaneous fibrohistiocytic tumor that typically arises on chronically sun-damaged skin, such as the head and neck, as a nondescript ulcerated papule, nodule, or tumor. The clinical prognosis is usually favorable and metastasis is rare. Pleomorphic dermal sarcoma (PDS), or undifferentiated pleomorphic sarcoma, is a recently introduced diagnostic moniker for AFX-like tumors with more aggressive clinical and histologic features such as necrosis and vascular invasion. The exact relationship between AFX and PDS has been debated. Diagnosis of these tumors is generally based on immunohistochemical staining to exclude other mimics. A wholly specific marker for this tumor does not exist, leading to diagnostic ambiguity in certain cases. Herein, we present a case of pleomorphic dermal sarcoma in a 53-year-old man with human immunodeficiency virus that displayed patchy S100 staining concerning for melanoma upon hospital pathology review. Next-generation sequencing analysis confirmed a mutation pattern consistent with published molecular signatures of AFX/PDS. In discussing this case, we review the current understanding of AFX/PDS and discuss diagnostic pitfalls, as well as emphasize on how next-generation sequencing techniques might improve accuracy in the diagnosis of tumors in the spectrum of AFX/PDS.

We are going to present a case of malignant fibrous histiocytoma in the right atrium, which is a very rare entity. The patient had a right atrial mass, which prolapsed through the tricuspid valve into the right ventricle, causing functional tricuspid valve stenosis. The tumor was completely resected and the patient had an uneventful postoperative period. Histopathological examination reported malignant fibrous histiocytoma. The patient presented to the emergency department five weeks after discharge with dyspnea and palpitation. Echocardiography and magnetic resonance imaging revealed recurrent right atrial tumor mass. His clinical status has worsened, with syncope and acute renal failure. On the repeated echocardiography, suspected tumor recurrence was observed in left atrium, which probably caused systemic embolization. Considering the aggressive nature of the tumor and systemic involvement, our Heart Council decided to provide palliative treatment by nonsurgical management. His status deteriorated for the next few days and the patient succumbed to a cardiac arrest on the 4th day.

Undifferentiated pleomorphic sarcoma is a common soft tissue sarcoma. Unfortunately, any attempt to describe the line of differentiation fails. It represents a final common pathway in tumors that undergoes progression towards dedifferentiation. We report a man with an undifferentiated pleomorphic sarcoma presenting as an exophytic pedunculated tumor of the left scapula. Histopathology analysis revealed spindle-shaped cells with great pleomorphism and numerous mitoses. Immunohistochemistry showed diffuse expression of vimentin. Wide local excision was performed after an oncology consultation. After two-years of follow-up, the patient has shown no evidence of recurrence or metastases.

Atypical fibroxanthoma (AFX) is a rare cutaneous fibrohistiocytic tumor that typically arises on chronically sun-damaged skin, such as the head and neck, as a nondescript ulcerated papule, nodule, or tumor. The clinical prognosis is usually favorable and metastasis is rare. Pleomorphic dermal sarcoma (PDS), or undifferentiated pleomorphic sarcoma, is a recently introduced diagnostic moniker for AFX-like tumors with more aggressive clinical and histologic features such as necrosis and vascular invasion. The exact relationship between AFX and PDS has been debated. Diagnosis of these tumors is generally based on immunohistochemical staining to exclude other mimics. A wholly specific marker for this tumor does not exist, leading to diagnostic ambiguity in certain cases. Herein, we present a case of pleomorphic dermal sarcoma in a 53-year-old man with human immunodeficiency virus that displayed patchy S100 staining concerning for melanoma upon hospital pathology review. Next-generation sequencing analysis confirmed a mutation pattern consistent with published molecular signatures of AFX/PDS. In discussing this case, we review the current understanding of AFX/PDS and discuss diagnostic pitfalls, as well as emphasize on how next-generation sequencing techniques might improve accuracy in the diagnosis of tumors in the spectrum of AFX/PDS.

We are going to present a case of malignant fibrous histiocytoma in the right atrium, which is a very rare entity. The patient had a right atrial mass, which prolapsed through the tricuspid valve into the right ventricle, causing functional tricuspid valve stenosis. The tumor was completely resected and the patient had an uneventful postoperative period. Histopathological examination reported malignant fibrous histiocytoma. The patient presented to the emergency department five weeks after discharge with dyspnea and palpitation. Echocardiography and magnetic resonance imaging revealed recurrent right atrial tumor mass. His clinical status has worsened, with syncope and acute renal failure. On the repeated echocardiography, suspected tumor recurrence was observed in left atrium, which probably caused systemic embolization. Considering the aggressive nature of the tumor and systemic involvement, our Heart Council decided to provide palliative treatment by nonsurgical management. His status deteriorated for the next few days and the patient succumbed to a cardiac arrest on the 4th day.

Sarcomas are a broad family of mesenchymal malignancies exhibiting remarkable histologic diversity. We describe the multi-platform molecular landscape of 206 adult soft tissue sarcomas representing 6 major types. Along with novel insights into the biology of individual sarcoma types, we report three overarching findings: (1) unlike most epithelial malignancies, these sarcomas (excepting synovial sarcoma) are characterized predominantly by copy-number changes, with low mutational loads and only a few genes (TP53, ATRX, RB1) highly recurrently mutated across sarcoma types; (2) within sarcoma types, genomic and regulomic diversity of driver pathways defines molecular subtypes associated with patient outcome; and (3) the immune microenvironment, inferred from DNA methylation and mRNA profiles, associates with outcome and may inform clinical trials of immune checkpoint inhibitors. Overall, this large-scale analysis reveals previously unappreciated sarcoma-type-specific changes in copy number, methylation, RNA, and protein, providing insights into refining sarcoma therapy and relationships to other cancer types.

A patient high-grade undifferentiated pleomorphic soft-tissue sarcoma (UPS) from a striated muscle was previously orthotopically implanted in the right biceps femoris muscle of nude mice to establish a patient-derived orthotopic xenograft (PDOX) nude-mouse model. In the present study, two weeks after orthotopic transplantation of the UPS, mice were treated intraperitoneally with cisplatinum (CDDP), doxorubicin (DOX) or a novel anionic-phosphate-platinum compound 3Pt. Treatments were repeated weekly for a total of 3 times. Six weeks after transplantation, all mice were sacrificed and evaluated. After two weeks treatment, tumor sizes were as follows: control (G1): 2208.3 mm3; CDDP (G2): 841.8±3 mm3, p=0.0001; DOX (G3): 693.1±3 mm3, p=6.56E-7; 3Pt (G4): 333.7±1 mm3, p=4.8E-8. 3Pt showed significantly more efficacy compared to other therapy drugs tested: CDDP (p=0.0002), DOX (p=0.001). There were no animal deaths in any of the four groups. The present results suggest 3Pt is a promising new candidate for UPS since it was demonstrated to be effective in a PDOX model.

A patient high-grade undifferentiated pleomorphic soft-tissue sarcoma (UPS) from a striated muscle was previously orthotopically implanted in the right biceps femoris muscle of nude mice to establish a patient-derived orthotopic xenograft (PDOX) nude-mouse model. In the present study, two weeks after orthotopic transplantation of the UPS, mice were treated intraperitoneally with cisplatinum (CDDP), doxorubicin (DOX) or a novel anionic-phosphate-platinum compound 3Pt. Treatments were repeated weekly for a total of 3 times. Six weeks after transplantation, all mice were sacrificed and evaluated. After two weeks treatment, tumor sizes were as follows: control (G1): 2208.3 mm3; CDDP (G2): 841.8±3 mm3, p=0.0001; DOX (G3): 693.1±3 mm3, p=6.56E-7; 3Pt (G4): 333.7±1 mm3, p=4.8E-8. 3Pt showed significantly more efficacy compared to other therapy drugs tested: CDDP (p=0.0002), DOX (p=0.001). There were no animal deaths in any of the four groups. The present results suggest 3Pt is a promising new candidate for UPS since it was demonstrated to be effective in a PDOX model.

Sarcomas are a broad family of mesenchymal malignancies exhibiting remarkable histologic diversity. We describe the multi-platform molecular landscape of 206 adult soft tissue sarcomas representing 6 major types. Along with novel insights into the biology of individual sarcoma types, we report three overarching findings: (1) unlike most epithelial malignancies, these sarcomas (excepting synovial sarcoma) are characterized predominantly by copy-number changes, with low mutational loads and only a few genes (TP53, ATRX, RB1) highly recurrently mutated across sarcoma types; (2) within sarcoma types, genomic and regulomic diversity of driver pathways defines molecular subtypes associated with patient outcome; and (3) the immune microenvironment, inferred from DNA methylation and mRNA profiles, associates with outcome and may inform clinical trials of immune checkpoint inhibitors. Overall, this large-scale analysis reveals previously unappreciated sarcoma-type-specific changes in copy number, methylation, RNA, and protein, providing insights into refining sarcoma therapy and relationships to other cancer types.