Foreign Body Granuloma Masquerading as Remnant Lymphoma on 18F-FDG PET/CT.

A 54-year-old man complained of a growing nodule in the left upper arm, which was diagnosed as diffuse large B-cell lymphoma by postsurgical pathology. For baseline assessment, FDG PET/CT revealed intense uptake in the left upper arm, in addition to FDG-avid pleura lesions and regional, axillary, cervical, and mediastinal lymph nodes. After chemotherapy, the restaging scan showed complete remission of most involved lesions except for increased activity in the prior surgical site. The patient eventually underwent surgical resection again, and the diagnosis was confirmed as foreign body granuloma.