A 39-year-old man had been treated for rectal cancer 6 years ago by lower anterior resection of the rectum and perioperative radiochemotherapy. Since then follow-up had been unremarkable but now the patient presented with unspecific lower abdominal pain. The cause of the pain was identified as paraneoplastic retroperitoneal fibrosis secondary to metachronous pulmonary metastases of the rectal cancer.
Keywords: Abdominal pain; IgG4-related disease; Prednisolone; Retroperitoneal fibrosis, paraneoplastic; Retroperitoneal fibrosis, secondary.