: Soft Tissue Sarcomas are rare mesenchymal tumors with many subtypes. Clean margin-wide resection is recommended for treatment. The guidelines recommend that sarcoma treatments be carried out in sarcoma centers. In this study, the location, histopathological features, clinical and demographic features, recurrence, and prognosis of retroperitoneal sarcomas were investigated.

The demographic, histopathological, and immunohistochemical data of the patients who were operated on with the diagnosis of intraabdominal mass at Istanbul Medeniyet University Göztepe Prof. Dr. Süleyman Yalçın City Hospital from March 2016 to December 2020 were retrospectively evaluated. Ethical approval was obtained from Istanbul Medeniyet University Göztepe Prof. Dr. Süleyman Yalçın City Hospital Ethics Committee.

Patients diagnosed with pathological sarcoma subclass were included in the study. Patients younger than 18 years were excluded from the study. Visceral organ-origin sarcomas and extremity sarcomas were also excluded from the study. GIST's were included in sarcoma subtypes by WHO in 2013. However, they were not included in the study due to their solid organ origin.

The data of 18 patients' whore remained after the exclusion criteria were analyzed retrospectively. Pathology samples of the patients were re-examined by a single pathologist.

The demographic analysis was used for statistics.

Inclusion Criteria:

• Patients operated with the diagnosis of intra-abdominal mass
• patients diagnosed with pathological sarcoma subclasses

Exclusion Criteria:

• Patients younger than 18 years
• Visceral organ-origin sarcomas
• extremity sarcomas
• GIST