Cryoablation as a downsizing strategy enabling R0 resection in a giant mediastinal desmoid tumor: a case report.

Background: Endothoracic desmoid tumors are rare, locally aggressive soft-tissue neoplasms whose intrathoracic location often precludes safe surgical resection. The historical paradigm of upfront radical surgery has shifted toward a more conservative and stepwise approach, prioritizing active surveillance and non-surgical treatments whenever feasible. Surgical resection is now typically reserved for selected cases. Percutaneous cryoablation (PCA) has emerged as a promising minimally invasive treatment and valid therapeutic alternative for selected patients, although its role as a tumor downsizing strategy remains poorly defined. Case Description: We report the case of a 64-year-old woman presenting with a giant anterior mediastinal desmoid tumor causing progressive respiratory symptoms and pain. Initial systemic therapies were associated with disease progression, and despite second-line treatment, tumor control was not achieved, leading to surgical contraindication. Within the framework of the prospective CRYODESMO-O1 trial, the multidisciplinary team proposed PCA, resulting in a significant reduction in tumor size and improved anatomical relationships. This evolution allowed reconsideration of surgical resection, which was subsequently performed via a left sternothoracotomy approach. Final pathological examination demonstrated less than 10% residual desmoid tissue with complete (R0) resection. At the last follow-up at 8 months after surgery the patient was well and without recurrence. Conclusions: In this case, cryoablation was associated with marked tumor downsizing and a major pathological response, facilitating reconsideration of surgical resection in a tumor initially deemed unresectable. This approach may represent a potential component of multimodal management in carefully selected patients, although further evidence is needed to confirm its role.