Freezing nitrogen ethanol composite as an alternative to liquid nitrogen in giant cell tumor cryotherapy: a case report and literature review.

Introduction: Giant cell tumor (GCT) of bone is a benign but locally aggressive tumor, commonly found around the knee in young adults. Despite surgical excision, GCTs are known for their high recurrence rates, prompting the use of adjuvant therapies such as cryotherapy. Liquid nitrogen is a widely used cryoablation agent but carries the risk of complications including skin necrosis, nerve injury, and pathological fractures. A newer agent, freezing nitrogen ethanol composite (FNEC), has emerged as a potentially safer alternative with similar tumoricidal effects and fewer side effects. Case Presentation: A 37-year-old man presented with a progressively enlarging, painless lump on his left knee that had been present for 5 years. Physical examination revealed a firm, non-tender mass the size of a tennis ball. Imaging studies suggested a GCT, and a preoperative biopsy confirmed a diagnosis of tenosynovial GCT. The patient underwent intralesional curettage followed by cryotherapy using FNEC as an adjuvant. To support structural integrity post-curettage, internal fixation with a plate and screw was performed. Discussion: FNEC acts through several mechanisms including cell shrinkage, DNA fragmentation, and induction of apoptosis. Compared to liquid nitrogen, FNEC appears to provide a more controlled cryogenic effect with less risk of injury to surrounding tissues. In this case, no complications were observed during recovery. Conclusion: FNEC may offer a safer and effective cryotherapy option for GCT management. Further clinical research is needed to confirm its long-term safety and efficacy compared to traditional methods.