A CT scan of a 69-year-old male patient, performed for staging of suspected lung carcinoma, incidentally showed an irregular lesion of 10 cm in the upper abdomen. Further investigation using FDG-PET showed only moderately increased glucose metabolism, whereas Tc-99m MDP SPECT revealed intense osteoblastic activity inside the lesion. A CT-guided biopsy was performed and histologic analysis established the diagnosis of heterotopic mesenteric ossification. This pathology is rare and mostly diagnosed when it is complicated by small bowel obstruction.