F-18 FDG PET of foreign body granuloma: pathologic correlation with imaging features in 3 cases

Retained textiles with foreign body granulomatous reaction can form mass-mimicking soft tissue tumors, which may cause diagnostic, clinical, and medicolegal problems. In this study, we present 3 cases of foreign body granuloma by retained textiles, and demonstrate FDG PET findings with detailed pathologic correlation. We also provide a review of previous literatures.

Three patients (all females; age range, 48-61 years) with histopathologic diagnosis of mass-forming foreign body granuloma caused by retained textiles were retrospectively studied. They underwent an FDG PET scan in our institute. The mass was located in the abdominopelvic cavity in all cases. The time interval between the prior surgery and the PET acquisition was 11 months, 15 or 19 years, and 26 years, respectively.

Intense FDG uptake with a ring-shaped pattern was observed in 2 cases, while no uptake in 1 case. Microscopically, 2 with ring-shaped FDG uptake showed a cellular foreign body reaction peripherally, and artificial textile fibers and acellular eosinophilic amorphous materials in the central portion. In the one without FDG uptake, the mass was composed of mainly necrotic debris surrounding by a thick layer of well-formed collagen fibers. In previous case reports describing the accumulation of FDG in foreign body granulomas, 9 of 10 cases showed intense FDG uptake with a ring-shaped pattern.

The ring-shaped pattern of FDG uptake seems to well characterize pseudotumor with foreign body granulomas. However, the pattern of FDG accumulation in retained textile with foreign body granulomas may vary due to histologic features.