Sonographic features of lymphoma of the major salivary glands diagnosed with ultrasound-guided core needle biopsy in Sjögren's syndrome.

Objectives: To identify ultrasound (US) features of lymphomas (L) of major salivary glands (SGs) in primary Sjögren's syndrome (pSS) patients and to differentiate US pattern of L and non-L.

Methods: Prospectively, from September 2019 to March 2021, 27 pSS-patients with clinical findings suspicious for L of the SGs underwent US evaluation followed by US-guided core-needle biopsy (CNB). For each patient, we assessed the OMERACT score, dichotomised (0/1 "lower", 2/3 "higher"), and we compared it between L-pSS and nonL-pSS groups. For focal lesions, echogenicity, inner appearance, shape, margins, presence of septa, vascularisation and posterior acoustic features were also assessed and compared between the two groups; we planned to consider as "suspicious" features more frequently associated with L. We expected to compare frequencies at which two or more "suspicious" features were simultaneously present between L-pSS and nonL-pSS. P<0.05 were considered statistically significant.

Results: L-pSS showed more inhomogeneous glandular pattern (100% vs. 69.2% higher OMERACT; p=0.0407). For focal lesions, the "suspicious" features identified were: OMERACT grade 3, very hypoechoic, homogenous, oval shape, well-defined margins, presence of septa, colour-Doppler vascularization, posterior acoustic enhancement. 6/8 and 7/8 simultaneous suspicious features were significantly higher among L-pSS patients, compared to nonL-pSS (88.9% vs. 28.6%, p=0.034 for 6/8 features; 77.8% vs. 14.3%, p=0.040 for 7/8 features).

Conclusions: L of the major SGs in pSS was always associated with OMERACT scores 2 or 3 and presented with diffuse or focal patterns. For focal lesions, the association of more "suspicious" features made the diagnosis of L increasingly more likely. This information can help to improve planning of US-guided CNB.