Introduction Teratomas stem from the three germ layers, resulting in heterogeneous masses formed of pluripotent stem cells. Their rarity, 0.13% of adrenal disease (Li, et al., 2015), and growth potential, up to 38cm (Kuo, et al., 2017), make surgical management challenging This report describes a right adrenal teratoma with significant extension into the retroperitoneum. Case presentation A 62-year old was referred to endocrine surgery team with a large right adrenal mass. Abdominal computed tomography revealed a 10x9cm right adrenal mass with isodense, fluid and fat components. This was reported to be a lipomyoma, previously complicated by haemorrhage. The patient proceeded for open resection however intraoperatively the mass was indistinguishable from the right kidney. Right nephrectomy was performed and further dissection revealed extensive involvement of the inferior vena cava. It was decided for sub-total cystectomy and debulking rather than caval resection in context of this being benign. During debulking, hair/calcifications were encountered. Final histopathology was reported as dermoid cyst with changes suggestive of rupture and repair. The patient had a chyle leak post operatively that was managed conservatively. Conclusion Adrenal masses are challenging in diagnosis but distinguishing benign from malignant causes is key to management. There is unpredictability of intra-operative findings and need for flexibility in surgical planning when approaching sizeable adrenal lesions. Decisions for limits of surgical resection vary between mass aetiology and must be carefully considered. References Kuo, E. et al., 2017. Adrenal Teratoma: a Case Series and Review of the Literature. Endocrine Pathology, 28(2), pp. 152-158. Li, S. et al., 2015. Primary adrenal teratoma: Clinical characteristics and retroperitoneal laparoscopic resection in five adults. Oncology Letters, 10(5), pp. 2865-2870 .