Leiomyosarcoma of the Mediastinum Depicted on CT Images: A Rare Origin Case and Literature Review

Abstract

Introduction: Leiomyosarcoma (LMS), a malignant smooth muscle tumor, accounts for 10%–20% of soft tissue sarcomas. Primary mediastinal LMS is rare, with only 13 cases reported in the last two decades. This study aims to delineate its clinical and radiological characteristics through a novel case presentation and literature review. Methods: We report the case of a 57-year-old male presenting with progressive dyspnea and back pain. Diagnostic workup included contrastenhanced chest CT, histopathological analysis of CT-guided biopsy specimens, and immunohistochemical staining (positive for Vim, Des, SMA, and Calponin; negative for S100 and CD34). A systematic PubMed review of mediastinal LMS cases was performed to summarize imaging and pathological features.

Results: Imaging revealed a 16.1 × 10.9 cm heterogeneous posterior mediastinal mass with necrotic foci, vascular encasement, and right pleural effusion. Histopathology showed spindle-shaped tumor cells with a Ki-67 index of 40%, confirming LMS. Literature synthesis (n=14 cases) demonstrated that 71.4% of tumors exceeded 5 cm, with a predilection for the anterior mediastinum (71.4%) and heterogeneous enhancement (100%).

Discussion: Mediastinal LMS radiologically mimics other malignancies but exhibits distinctive pathological markers (SMA/ Desmin+). Surgical resection remains the primary treatment; our patient received neoadjuvant chemotherapy (liposomal doxorubicin/dacarbazine) and achieved a partial response. This case highlights the importance of multidisciplinary collaboration (imaging-pathology correlation) for the timely diagnosis of this aggressive neoplasm.