Introduction
The malignant fibrous histiocytoma (MFH), formerly known as undifferentiated pleomorphic sarcoma (UPS), is a high-grade soft-tissue sarcoma (STS). Previously, several soft-tissue sarcomas (STS) were referred to as malignant fibrous histiocytoma (MFH) in the literature. However, with advances in cytogenetics and immunohistochemistry research, these were eventually categorized as separate entities.
What Is Undifferentiated Pleomorphic Sarcoma?
Undifferentiated pleomorphic sarcoma (UPS) is a high-grade aggressive soft-tissue sarcoma formerly recognized as malignant fibrous histiocytoma (MFH). Instead of histiocytes, mesenchymal stem cells are the most likely source of the tumor. It can impact soft tissues, bones, and the retroperitoneum and spread to other organs. Undifferentiated pleomorphic sarcoma (UPS) is most common in the legs and limbs.
What Is the Etiology of Undifferentiated Pleomorphic Sarcoma?
Undifferentiated pleomorphic sarcomas (UPS) have a specific pathogenic mechanism that is unknown. Soft-tissue sarcomas (STS), in general, are composed of diverse populations of cells with mesenchymal traits that can result from simple or complicated genetic changes. Undifferentiated pleomorphic sarcomas (UPS) exhibit a variety of possible cellular backgrounds, mutational markers, and altered signaling pathways. The carcinogenesis of undifferentiated pleomorphic sarcomas (UPS) is thought to be triggered by a subpopulation of cells known as side population (SP) cells, which the Hoechst dye efflux test may identify. Radiation therapy, when used to treat other forms of cancer detected in the same place, has also been associated with this illness – but this is extremely rare.
According to an experimental model, these cells have an improved potential for self-renewal, growth, and proliferation and can mimic tumor development. Undifferentiated pleomorphic sarcomas (UPS)-derived side population (SP) cell investigations revealed that the Hedgehog and Notch signaling pathways and their downstream transcriptional targets are highly elevated at both the subcellular and tissue levels. Undifferentiated pleomorphic sarcomas (UPS) have also been found to have mutations in the following:
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Tumor protein 53 (TP53).
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Cyclin-dependent kinase inhibitor 2A (CDKN2A).
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Retinoblastoma-associated protein (RB1).
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Transcriptional regulator ATRX (ATRX) genes.
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PR domain zinc finger protein 10 (PRDM10).
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Triple functional domain protein (TRIO) gene fusions.
What Is the Epidemiology of Undifferentiated Pleomorphic Sarcoma?
Undifferentiated pleomorphic sarcomas (UPS) are included in the World Health Organization's 2020 categorization of soft-tissue sarcomas (STS) as malignant tumors of unclear distinction. Undifferentiated pleomorphic sarcomas (UPS) accounted for 17.1 % of the 26,758 cases and is the second most prevalent soft-tissue sarcomas (STS) after leiomyosarcoma, independent of the underlying tumor location. Males had much higher incidence rates than females, and white males were impacted more frequently than black males. Incidence also is the highest during the sixth decade of life.
What Are the Signs and Symptoms of Undifferentiated Pleomorphic Sarcoma?
Undifferentiated pleomorphic sarcomas (UPS) usually manifests as an asymptomatic, inconspicuous, quickly developing cutaneous or subcutaneous lump with no visible skin abnormalities. However, intrathoracic, internal, and intraabdominal undifferentiated pleomorphic sarcomas (UPS) can cause mass effects and symptoms. The extremities are the most usually involved area, followed by the trunk, retroperitoneum, and left atrium.
How Is Undifferentiated Pleomorphic Sarcoma Diagnosed?
Diagnosing undifferentiated pleomorphic sarcoma includes histology and immunohistochemistry confirming the diagnosis, examination, and workup, including imaging of the primary tumor, lymph nodes, and distant metastases.
The TNM Staging Criteria- Will differ based on where the tumor is located.
Magnetic Resonance Imaging (MRI)- With contrast is recommended to detect tumor size, invasion of visceral tissues, and neurovascular involvement.
Non-contrast Computed Tomography (CT)- When internal viscera or retroperitoneal involvement is suspected, non-contrast computed tomography (CT) of the chest, pelvis, and abdomen should be considered. Sometimes, a whole spine, head, and neck magnetic resonance imaging (MRI) or computed tomography (CT) may be ordered.
Sentinel Lymph Node Biopsy (SLNB)- It is recommended to diagnose undifferentiated pleomorphic sarcomas (UPS).
Positron Emission Tomography (PET)- F-fluorodeoxyglucose positron emission tomography (PET) scan is a valuable prediction tool in patients with soft tissue sarcoma (STS) and bone sarcomas.
What Is the Treatment for Undifferentiated Pleomorphic Sarcoma?
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En Bloc Surgical Excision - With microscopically negative margins is the standard therapy for undifferentiated pleomorphic sarcomas (UPS) of the head, trunk, neck, and extremities, especially for stage I tumors. This can be accomplished with extensive local excision with two cm margins of uninvolved tissue; it may be more challenging due to the presence of critical neurovascular systems.
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Radiotherapy (RT) - When the margins are near the tumor (one cm), microscopically positive, and include bone, major blood arteries, or nerves, postoperative radiotherapy (RT) is required.
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External Beam Radiotherapy (RT) - Intraoperative radiotherapy (IORT) used is 10-16 Gy, low-dose brachytherapy (LDR) uses 45 Gy, or its high-dose counterpart can all be used to deliver effective radiotherapy (RT) with a five cm margin (HDR).
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Chemotherapy - Various antineoplastics treat advanced, extensive, or incurable stages of undifferentiated pleomorphic sarcomas (UPS). The used chemotherapy regime is anthracycline plus ifosfamide.
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Extremity Amputation - If the limb-sparing surgery does not improve overall survival rates, extremity amputation is the last option.
What Is the Differential Diagnosis of Undifferentiated Pleomorphic Sarcomas (UPS)?
The differential diagnosis of undifferentiated pleomorphic sarcomas (UPS) is:
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Leiomyosarcoma.
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Liposarcoma.
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Dermatofibrosarcoma protuberans.
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Myxofibrosarcoma.
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Malignant peripheral nerve sheath tumor.
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Osteosarcoma.
What Are the Complications That Occur with Undifferentiated Pleomorphic Sarcomas (UPS)?
The most common complications include the following:
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Local recurrences.
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Metastasis.
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Death.
Conclusion
Undifferentiated pleomorphic sarcoma (UPS) is a kind of aggressive soft-tissue sarcoma (STS) with a high grade. Patient education regarding undifferentiated pleomorphic sarcoma (UPS) is critical for comfort, therapy adherence, and follow-up. In addition, community-level education is essential for increasing illness awareness and facilitating the formation of sarcoma organizations and support groups. Furthermore, molecular diagnosis for undifferentiated pleomorphic sarcoma (UPS) has yet to be formally defined; research should be directed into this area for further characterization, prognosis, and therapeutic objectives.
