2021, Vol. 3, Issue 2, Part C

The majority of soft tissue tumors are present in the extremities; however, many other sites can be affected, including the retroperitoneum. Retroperitoneal tumors represent a rare entity, and sarcomas are the most commonly seen tumors. Sarcomas are mesenchymal in origin; they arise from skeletal and extra skeletal connective tissues, including the peripheral nervous system. In a population-based series reported in the SEER database, the average annual incidence of retroperitoneal sarcomas was approximately 2.7 cases per million populations. Leiomyosarcomas are second in frequency at this location and are also the most aggressive of the sarcomas.

Here we reported a case of a 48-year-old female, who presented with a left-sided abdominal lump associated with pain. Abdominal imaging showed a retroperitoneal tumor-infiltrating the ureter. Histopathological examination of the excised mass showed features of malignant retroperitoneal tumor with the possible differential diagnosis included 1. Leiomyosarcoma, 2. Malignant Peripheral Nerve Sheath Tumor.

Advised immunohistochemistry, for further evaluation and confirmation. Immunohistochemistry with a panel of antibodies confirmed the case as Retroperitoneal Leiomyosarcoma.