A Rare Case of Retroperitoneal Leiomyosarcoma Presenting as Shortness of Breath.

Retroperitoneal leiomyosarcomas (RLMSs) are rare soft tissue sarcomas. These sarcomas often grow silently until compressive symptoms arise, making incidental imaging a common mode of detection. Complete surgical resection remains the cornerstone of treatment, though this can be challenging due to tumor invasion of critical structures. Here, we report the case of a 78-year-old female with a history of chronic obstructive pulmonary disease (COPD), diabetes, and hypertension who presented with acute shortness of breath. Initial imaging for presumed COPD exacerbation incidentally revealed a large retroperitoneal mass compressing the inferior vena cava (IVC). Subsequent CT-guided core needle biopsy confirmed an RLMS. Given the tumor's proximity to the IVC and the patient's severe comorbidities, surgical resection was deemed too high risk. A multidisciplinary tumor board recommended radiation therapy, which she is currently undergoing. This case exemplifies the typical clinical course of RLMSs, including incidental detection, diagnostic confirmation by core needle biopsy, and challenges in surgical management. The case also highlights the importance of a multidisciplinary approach to manage RLMS and the necessity for specialized care at centers experienced in handling these rare tumors. Advances in targeted therapies, including tyrosine kinase inhibitors, offer future directions in therapy.