Superior vena cava syndrome associated with alveolar soft part sarcoma – a possible paraneoplastic mechanism

Abstract

Introduction Alveolar soft part sarcoma (ASPS) is an exceptionally rare soft tissue sarcoma, accounting for less than 1% of all cases. It typically presents as an indolent, slow-growing, painless mass. Superior vena cava (SVC) syndrome is usually caused by extraluminal compression from intrathoracic malignancies.

Case outline We report the case of a 53-year-old male who developed acute symptoms of SVC thrombosis. Imaging revealed extensive venous thrombosis without significant extrinsic venous compression. The clinical findings mimicked classic SVC syndrome, yet the underlying mechanism was intraluminal obstruction caused by thrombus formation. Histopathological evaluation confirmed the diagnosis of ASPS.

Conclusion To our knowledge, this is the first reported case of ASPS presenting with SVC syndrome secondary to extensive thrombosis rather than compression. Although the underlying mechanism remains uncertain, this case raises the possibility of a paraneoplastic mechanism. Awareness of this atypical manifestation may facilitate earlier recognition and timely management in similar presentations.

Keywords: alveolar soft part sarcoma; superior vena cava syndrome; thrombosis; paraneoplastic; chemotherapy