Date: Monday, October 22, 2018
Session Title: Sjögren's Syndrome – Basic and Clinical Science Poster
Session Type: ACR Poster Session B
Session Time: 9:00AM-11:00AM
Background/Purpose: primary Sjögren’s syndrome (SS) is the autoimmune disease having the highest risk of lymphoma. The differential diagnosis between benign and malignant lymphoproliferation is sometimes difficult. Among imaging procedures, 18F-FDG PET could be useful for that purpose.
The purpose was to compare 18F-FDG PET results between patients with and without lymphoma to identify PET pattern associated with lymphomas in primary SS.
Retrospective study conducted in 2 centers including primary SS patients (according to ACR/EULAR 2016 criteria) who undergo 18F-FDG PET. We compared PET abnormalities in patients with and without lymphoma, the PET having been done before any chemotherapy. Two independent readers analyzed PET blind to lymphoma diagnosis. PET score previously described by Cohen et al. was calculated.
45 patients were included; 15 had lymphoma: MALT (n=12), nodal marginal zone with plasmacytic differentiation (n=2), diffuse large B-cell (n=1). Patients with lymphoma had more frequently parotid gland swelling (67% vs 20 %, p=0.003) and higher ESSDAI score (24 [13.5-29] vs 9 [5-20], p=0.03), even after exclusion of lymphoma item (19 [11-27] VS 9 [5-20], p=0.03).
Compared to non-lymphoma patients, mean size (45.5 [38-56] mm vs. 40 [37-41] mm; p = 0.048) and maximum standardized uptake value (SUVmax) of the parotid glands (5.6 [5-6.9] vs 3.8 [3.2-4.4]; p = 0.001) were higher in lymphoma patients. 53.3% of patients with lymphoma and 43.3% without lymphoma had lymph node FDG uptake, but neither their number nor their repartition or mean SUV differ between them.
Pulmonary uptake was observed in 6 (40%) patients with lymphoma and 6 (20%) without lymphoma (p=0.17). But in lymphoma patients, this uptake was focal in 5 (33.3%) patients (nodules or condensation) and in only one (3.3%) patient without lymphoma (p=0.01). Remaining patients had interstitial FDG uptake. Mean PET score (4 [2-4] vs. 2 [1-3] p=0.04) and SUVmax at any site (6.3 [5.6-7.3) vs. 4.2 [3.7-5.9] p =0.02) were significantly higher in lymphoma group.
The best combination retained for identifying patients with a currently evolving lymphoma was the highest SUVmax at parotid gland ≥ 4.7 and the pulmonary focal condensation or nodular lesions as being sensitive (sensibility=80.0%) and specific (specificity=83.3%) .
20 patients had PET guided biopsy of a hypermetabolic lesion that conducted to lymphoma diagnosis in 7 cases (46.6%). After chemotherapy for lymphoma, PET was available for 10 patients: complete regression of hypermetabolic lesions was observed in 6 patients (60%), and decreased uptake intensity in the 4 remaining patients. After a median follow-up of 19 months [13.5-30.3] months , one patient with diffuse large B-cell lymphoma relapsed.
Conclusion: some of the systemic manifestation of primary SS (lung, lymph nodes and salivary glands) can be assessed by 18F-FDG PET. Lymph nodes hypermetabolism is frequent and not associated with lymphoma. The best 18F-FDG PET abnormalities associated with lymphoma diagnosis are the highest SUVmax at parotid gland ≥ 4.7, and/or the pulmonary focal condensation or nodular lesions. Finally, PET can be helpful to guide biopsy toward the most hypermetabolic structure for diagnosing lymphoma
To cite this abstract in AMA style:Keraen J, Blanc E, Besson F, Le Guern V, Belkhir R, Henry J, Meyer C, Nocturne G, Mariette X, Seror R. Usefulness of 18F-FDG Positron Emission Tomography for Lymphoma Diagnosis in Patients with Primary Sjögren’S Syndrome [abstract]. Arthritis Rheumatol. 2018; 70 (suppl 10). https://acrabstracts.org/abstract/usefulness-of-18f-fdg-positron-emission-tomography-for-lymphoma-diagnosis-in-patients-with-primary-sjogrens-syndrome/. Accessed July 6, 2020.
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