• Spectrum of MRI features of HS-related anoperineal disease is wide. • Specific diagnosis of HS-related anoperineal disease is possible using MR imaging. • A combination of three MR signs allows distinction between HS and CD.

An 87-year-old woman with leg-type lymphoma underwent a staging 18F-FDG PET/CT, which demonstrated besides leg lymphomatous lesions a round, well-defined, preduodenal mass with moderate FDG uptake. This mass remained unchanged after chemotherapy treatment completion, despite a complete metabolic response of lymphomatous lesions. A biopsy revealed a gangliocytic paraganglioma. Subsequent 18F-FDOPA PET/CT and somatostatin receptor scintigraphy were positive and did not depict any other lesions.