Encountering the unicorn - abscopal effect after fractionated stereotactic radiosurgery for brain metastasis in renal cell carcinoma: a case report and review of the literature.

Clear cell renal cell carcinoma (ccRCC) is a malignancy with a diverse clinical presentation, often characterised by its resistance to conventional therapies. We present the case of a 53-year-old Indian male diagnosed with ccRCC, pT3aN0M1exhibiting lymphovascular invasion and non-contiguous tumour deposits in the left adrenal gland. Following an initial course of Pazopanib and subsequent Everolimus, the disease progressed. Notably, just 3 months after receiving fractionated stereotactic radiosurgery (FSR) for a cerebellar metastasis, spontaneous regression was observed at a distant skeletal site. This case highlights the significance of considering FSR as a therapeutic option for selected patients with ccRCC, as well as the potential role of an abscopal effect to impact the course of this aggressive malignancy.