Clinical utility of 18 F-fluorodeoxyglucose/positron emission tomography in diagnosis of immunoglobulin G4-related sclerosing sialadenitis.

OBJECTIVES/HYPOTHESIS: The aim of this study was to evaluate the utility of 18 F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) for accurately diagnosing immunoglobulin G4-related sclerosing sialadenitis (IgG4-SS).

STUDY DESIGN: Retrospective cohort study.

METHODS: We reviewed the records of 64 patients with IgG4-SS (35 male and 29 female patients) and 10 patients with clinically suspected IgG4-SS. Pathological diagnoses of patients clinically suspected with IgG4-SS included four cases of malignant lymphoma, one case of multicentric Castleman disease, one case of Sjögren's syndrome, and four cases of sialadenitis. All patients underwent submandibular gland (SMG) biopsies and baseline FDG-PET/CT evaluation. Clinical, serological, pathological, and PET/CT findings were analyzed. We also investigated maximum standardized uptake values (SUVmax) in the salivary glands of 15 patients with malignant disease of the salivary glands during the same period.

RESULTS: Increased FDG uptake in the SMG and parotid gland was found in 63 (98%) and 23 (35%) patients with IgG4-SS, respectively. FDG uptake of the bilateral SMG and unilateral SMG was recorded in 57 patients (89%) and six patients (9%), respectively. Mean SUVmax in patients with malignant disease of the salivary glands was significantly higher than that in patients with IgG4-SS (P = .035). We defined a positive test for IgG4-SS diagnosis as high SMG FDG uptake and serum IgG4 level ≥135 mg/dL, resulting in a sensitivity, specificity, and accuracy of 96.9%, 90.0%, and 86.4%, respectively.

CONCLUSIONS: FDG-PET/CT findings in combination with serological and clinical findings may have the capacity to diagnose IgG4-SS and lead to less-invasive biopsy procedures.

LEVEL OF EVIDENCE: 4. Laryngoscope, 128:1120-1125, 2018.