Primary retroperitoneal squamous cell carcinoma: A case report.

Retroperitoneal squamous cell carcinoma (SCC) is an extremely rare tumor originating from the retroperitoneum, with an unclear etiology and origin. Imaging studies are the preferred diagnostic modality for retroperitoneal tumors. The present study reports a case of retroperitoneal SCC and assesses its imaging characteristics. A 49-year-old female patient presented to the outpatient department of The Fifth Affiliated Hospital of Zunyi Medical University with a palpable abdominal mass detected 2 years ago. Ultrasound examination revealed two abnormal solid masses in the left adnexal region, suggesting a pelvic mass of undetermined origin. The patient was admitted to the hospital for further evaluation and treatment. Abdominal computed tomography (CT) and pelvic magnetic resonance imaging (MRI) revealed a retroperitoneal mass in the left pelvis. The patient subsequently underwent resection of the lesion and regional lymphadenectomy. Postoperative pathology confirmed poorly differentiated retroperitoneal SCC. After discharge, the patient received 6 months adjuvant chemotherapy and remained recurrence-free during the follow-up. Due to its deep location, proximity to several organs and non-specific clinical manifestations, retroperitoneal SCC is difficult to differentiate from other retroperitoneal tumors preoperatively using CT or MRI. Moreover, its treatment differs from that of common retroperitoneal tumors, such as leiomyosarcoma. Thus, summarizing the imaging features of retroperitoneal SCC is essential for guiding treatment selection and improving patient outcomes.