Rhabdomyosarcoma (RMS) is a highly aggressive form of cancer that develops from mesenchymal cells that have failed to fully differentiate into myocytes of skeletal muscle. Cells of the tumor are identified as rhabdomyoblasts.
Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract. GISTs arise in the smooth muscle pacemaker interstitial cell of Cajal, or similar cells. They are defined as tumors whose behavior is driven by mutations in the KIT gene (85%), PDGFRA gene (10%), or BRAF kinase (rare). 95% of GISTs stain positively for KIT (CD117). Most (66%) occur in the stomach and gastric GISTs have a lower malignant potential than tumors found elsewhere in the GI tract.
Liposarcomas are the most common subtype of soft tissue sarcomas, accounting for at least 20% of all sarcomas in adults. Soft tissue sarcomas are rare neoplasms with over 150 different histological subtypes or forms. Liposarcomas arise from the precursor lipoblasts of the adipocytes in adipose tissues. Adipose tissues are distributed throughout the body, including such sites as the deep and more superficial layers of subcutaneous tissues as well as in less surgically accessible sites like the retroperitoneum and visceral fat inside the abdominal cavity.
A synovial sarcoma is a rare form of cancer which occurs primarily in the extremities of the arms or legs, often in proximity to joint capsules and tendon sheaths. It is a type of soft-tissue sarcoma.
Desmoplastic small-round-cell tumor (DSRCT) is an aggressive and rare cancer that primarily occurs as masses in the abdomen. Other areas affected may include the lymph nodes, the lining of the abdomen, diaphragm, spleen, liver, chest wall, skull, spinal cord, large intestine, small intestine, bladder, brain, lungs, testicles, ovaries, and the pelvis. Reported sites of metastatic spread include the liver, lungs, lymph nodes, brain, skull, and bones. It is characterized by the EWS-WT1 fusion protein.
Paired-like homeobox 2b (PHOX2B), also known as neuroblastoma Phox (NBPhox), is a protein that in humans is encoded by the PHOX2B gene located on chromosome 4.
A transmissible cancer is a cancer cell or cluster of cancer cells that can be transferred between individuals without the involvement of an infectious agent, such as an oncovirus. Transmission of cancer between humans is rare. The evolution of transmissible cancer has occurred naturally in other animal species, but human cancer transmission is rare.
Ewing sarcoma is a type of cancer that forms in bone or soft tissue. Symptoms may include swelling and pain at the site of the tumor, fever, and a bone fracture. The most common areas where it begins are the legs, pelvis, and chest wall. In about 25% of cases, the cancer has already spread to other parts of the body at the time of diagnosis. Complications may include a pleural effusion or paraplegia.
Friend leukemia integration 1 transcription factor (FLI1), also known as transcription factor ERGB, is a protein that in humans is encoded by the FLI1 gene, which is a proto-oncogene.
CD99 antigen, also known as MIC2 or single-chain type-1 glycoprotein, is a heavily O-glycosylated transmembrane protein that is encoded by the CD99 gene in humans. The protein has a mass of 32 kD. Unusually for a gene present on the X chromosome, the CD99 gene does not undergo X inactivation, and it was the first such pseudoautosomal gene to be discovered in humans.
RNA-binding protein EWS is a protein that in humans is encoded by the EWSR1 gene on human chromosome 22, specifically 22q12.2. It is one of 3 proteins in the FET protein family. The q22.2 region of chromosome 22 encodes the N-terminal transactivation domain of the EWS protein and that region may become joined to one of several other chromosomes which encode various transcription factors, see and the FET protein family. The expression of a chimeric protein with the EWS transactivation domain fused to the DNA binding region of a transcription factor generates a powerful oncogenic protein causing Ewing sarcoma and other members of the Ewing family of tumors. These translocations can occur due to chromoplexy, a burst of complex chromosomal rearrangements seen in cancer cells. The normal EWS gene encodes an RNA binding protein closely related to FUS (gene) and TAF15, all of which have been associated to amyotrophic lateral sclerosis.
ERG is an oncogene. ERG is a member of the ETS family of transcription factors. The ERG gene encodes for a protein, also called ERG, that functions as a transcriptional regulator. Genes in the ETS family regulate embryonic development, cell proliferation, differentiation, angiogenesis, inflammation, and apoptosis.
Large tumor suppressor kinase 1 (LATS1) is an enzyme that in humans is encoded by the LATS1 gene.
Embryonal rhabdomyosarcoma (EMRS) is a rare histological form of cancer in the connective tissue wherein the mesenchymally-derived malignant cells resemble the primitive developing skeletal muscle of the embryo. It is the most common soft tissue sarcoma occurring in children. Embryonal rhabdomyosarcoma is also known as PAX-fusion negative or Fusion-Negative rhabdomyosarcoma, as tumors of this subtype are unified by their lack of a PAX3-FOXO1 fusion oncogene. Fusion status refers to the presence or absence of a fusion gene, which is a gene formed from joining two different genes together through DNA rearrangements. These types of tumors are classified as embryonal rhabdomyosarcoma "because of their remarkable resemblance to developing embryonic and fetal skeletal muscle."
A solid pseudopapillary tumour is a low-grade malignant neoplasm of the pancreas of papillary architecture that typically afflicts young women.
Plexiform angiomyxoid myofibroblastic tumor (PAMT), also called plexiform angiomyxoma, plexiform angiomyxoid tumor, or myxofibroma, is an extremely rare benign mesenchymal myxoid tumor along the gastrointestinal tract. Most of PAMTs occur in the gastric antral region, but they can be situated anywhere in the stomach. There is one recorded case of PAMT located in duodenum.
Fibroblastic and myofibroblastic tumors (FMTs) develop from the mesenchymal stem cells which differentiate into fibroblasts and/or the myocytes/myoblasts that differentiate into muscle cells. FMTs are a heterogeneous group of soft tissue neoplasms. The World Health Organization (2020) defined tumors as being FMTs based on their morphology and, more importantly, newly discovered abnormalities in the expression levels of key gene products made by these tumors' neoplastic cells. Histopathologically, FMTs consist of neoplastic connective tissue cells which have differented into cells that have microscopic appearances resembling fibroblasts and/or myofibroblasts. The fibroblastic cells are characterized as spindle-shaped cells with inconspicuous nucleoli that express vimentin, an intracellular protein typically found in mesenchymal cells, and CD34, a cell surface membrane glycoprotein. Myofibroblastic cells are plumper with more abundant cytoplasm and more prominent nucleoli; they express smooth muscle marker proteins such as smooth muscle actins, desmin, and caldesmon. The World Health organization further classified FMTs into four tumor forms based on their varying levels of aggressiveness: benign, intermediate, intermediate, and malignant.
Lipofibromatosis-like neural tumor (LPF-NT) is an extremely rare soft tissue tumor first described by Agaram et al in 2016. As of mid-2021, at least 39 cases of LPF-NT have been reported in the literature. LPF-NT tumors have several features that resemble lipofibromatosis (LPF) tumors, malignant peripheral nerve sheath tumors, spindle cell sarcomas, low-grade neural tumors, peripheral nerve sheath tumors, and other less clearly defined tumors; Prior to the Agaram at al report, LPF-NTs were likely diagnosed as variants or atypical forms of these tumors. The analyses of Agaram at al and subsequent studies uncovered critical differences between LPF-NT and the other tumor forms which suggest that it is a distinct tumor entity differing not only from lipofibromatosis but also the other tumor forms.
Myxofibrosarcoma (MFS), although a rare type of tumor, is one of the most common soft tissue sarcomas, i.e. cancerous tumors, that develop in the soft tissues of elderly individuals. Initially considered to be a type of histiocytoma termed fibrous histiocytoma or myxoid variant of malignant fibrous histiocytoma, Angervall et al. termed this tumor myxofibrosarcoma in 1977. In 2020, the World Health Organization reclassified MFS as a separate and distinct tumor in the category of malignant fibroblastic and myofibroblastic tumors.
The FET protein family the EWSR1 protein encoded by the EWSR1 gene located at band 12.2 of the long arm of chromosome 22; 2) the FUS protein encoded by the FUS gene located at band 16 on the short arm of chromosome 16; and 3) the TAF15 protein encoded by the TAF15 gene located at band 12 on the long arm of chromosome 7 The FET in this protein family's name derives form the first letters of FUS, EWSR1, and TAF15.
