Case 295: Pseudomyxoma from Mucinous Adenocarcinoma of the Appendix Extending from the Retroperitoneum into the Thigh

History A 57-year-old man with no remarkable past medical history presented to an outside institution with painless swelling in his right thigh of 6 months duration. He denied any trauma to the site. At that time, physical examination demonstrated swelling in his right upper thigh. All other work-up, including complete blood count and chest radiography, yielded negative results. The initial diagnosis was lymphangioma of the thigh. He continued to experience worsening swelling in his right upper thigh with no other symptoms over the next year. He was referred to our facility, where he underwent US evaluation of the thigh lesion, an MRI scan encompassing the entire extent of his thigh lesion, and a CT scan of his abdomen and pelvis.