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600 Retroperitoneal metastatic pelvic adamantinoma: a novel location mimicking ovarian malignancy and review of the current literature

Introduction/Background Adamantinoma is a rare primary low-grade malignant tum­­­­­­our of the appendicular skeleton. It primarily affects the long bones and is most commonly found in the tibia. The disease process has an indolent course and histogenic origin has not been clearly defined, however there have been several suggestions pertaining to a vascular origin in the literature. Local recurrences and lung metastases occur over a protracted duration. Less frequently, they have also been reported elsewhere; including four documented cases of soft tissue and five of pelvic bony adamantinoma. There is only one documented case of adamantinoma of the ovary and one of concurrent unrelated primary tumour. There are also no reports available regarding surgical management of a retroperitoneal adamantinoma of the pelvis within a gynaecological oncology surgical setting. Clinical guidelines have not yet been established. Results We present the case of a 65-year-old female with known recurrent and metastatic right tibial disease. On further investigation, a Positron Emission Tomography scan identified a primary breast lesion and an 11 cm mass in the right iliac fossa of suspected ovarian malignancy amenable to surgical resection (figure A). The patient underwent total abdominal hysterectomy, bilateral salpingo-oophorectomy and resection of a retroperitoneal mass arising from the pelvic sidewall encompassing the iliac vasculature. The tumour was cleaved from the external iliac artery successfully, however the external iliac vein perforated during dissection. A Satinsky clamp was placed and a small cuff of vein wall was removed alongside adherent tumour. The vein defect was closed with 5–0 prolene, ensuring a patent lumen (figure B). The patient made an uneventful recovery with histology confirming metastatic disease. Conclusion We present an overview of adamantinoma and highlight a previously undocumented gynaecological oncology surgical approach to this novel location of metastatic disease mimicking possible ovarian malignancy. We further explore disease histogenesis and also comment on an incidental finding or primary breast cancer. Particularly in uncommon locations, its heterogeneous nature presents radiological and histological challenges regarding diagnosis and treatment. Such cases warrant a full complement of MDT specialist knowledge and expertise; with advanced surgical skills and experience regarding retroperitoneal and pelvic sidewall anatomy. We also highlight a paucity of recommendations for surveillance and follow up and propose an individualised approach. We report on this unusual case to assist clinicians in the building of a consensus opinion for optimal adamantinoma case management under current circumstances where formal guidelines do not exist. Disclosures None