Gangoli, AparnaGhosh, TriparnaChippalkatti, Komal DKulgod, Sanjeev2024-09-242024-09-242023-08Gangoli Aparna, Ghosh Triparna, Chippalkatti Komal D, Kulgod Sanjeev. A Dedifferentiated Solitary Fibrous Tumor in Mesentry with Osteosarcomatous Differentiation . International Journal of Contemporary Medical Research. 2023 Aug; 10(8): 1-42393-915X2454-7379https://imsear.searo.who.int/handle/123456789/228169Introduction: Solitary fibrous tumor, a mesenchymal neoplasm, was initially observed in pleura. Though they were later found in many extra pleural sites. It rarely occurs in mesentery. The biology of solitary fibrous tumor is unpredictable, it ranges from benign to overtly malignant. Dedifferentiation, a phenomenon which is morphologically characterized by abrupt transition between the well differentiated component and high-grade areas of tumor, is well described in soft tissue and bone tumors. However, dedifferentiation within solitary fibrous tumor is a rare phenomenon. Case report: We report a case of dedifferentiated solitary fibrous tumor arising in mesentery. Computed tomography revealed a large well-lobulated heterogeneously enhanced solid necrotic mass lesion involving the pelvic abdomen. Macroscopically, the resected tumor was 24 x 20 x 10 cm. microscopic examination revealed a malignant spindle cell tumor juxtaposed with osteosarcomatous component. The spindle cell component showed diffuse expression of SMA, CD34 & STAT6. The osteosarcomatous component showed diffuse expression of SATB2. Conclusion: This is a rare case of mesenteric dedifferentiated solitary fibrous tumor with osteosarcomatous differentiation.Dedifferentiated Solitary Fibrous TumorMesentryJournal ArticleIndiaHOD, Department of Pathology, Cytecare Cancer Hospital, Bangalore, Karnataka-560064Fellow-tumor Pathology, Department of Pathology, Cytecare Cancer Hospital, Bangalore, Karnataka-560064Consultant Pathologist, Department of Pathology, Cytecare Cancer Hospital, Bangalore, Karnataka-560064Consultant Oncosurgeon, Department of Oncosurgery, Radon Cancer Centre, Hubli, Karnataka-580021, India