Sjögren Syndrome




Keywords

Sjögren syndrome, parotid glands, imaging

 




Introduction


Sjögren syndrome (SS) is a chronic autoimmune disorder characterized by inflammatory destruction of the body’s exocrine glands and may be considered primary or secondary, in association with other autoimmune disorders, such as collagen vascular diseases. Although SS can present with a variety of symptoms, both glandular and extraglandular, initial presenting symptoms most commonly include decreased secretions of the major and minor salivary glands, leading to dry mouth and dry eyes, or sicca syndrome. In particular, involvement of the parotid glands can present as recurrent and tender swelling. Salivary gland dysfunction in SS reduces acinar cell production of serous saliva. This leads to mucous plugs within the salivary gland, resulting in obstructive sialoadenitis and possible superimposed inflammation. Furthermore, the insidious autoimmune process confers an increased risk for lymphoma. Both computed tomography (CT) and magnetic resonance imaging (MRI) are suitable options for evaluating the affected parotid glands, and sialography can be also performed to further evaluate the salivary ducts.




Temporal Evolution: Overview


SS leads to a fairly characteristic progression of changes in the parotid glands ( Fig. 41.1 ). Initially, the parotid glands in SS may appear normal on imaging. Eventually, a classic miliary pattern of tiny cysts forms within the glands bilaterally, which appears as punctate foci of hypoattenuation on CT and high signal on T2-weighted MRI. The glands tend to become swollen diffusely from inflammation, although they may be asymmetric. Punctate calcifications may also form within the parotid glands, which is a classic feature of intermediate to late stages of SS and are best depicted on CT ( Fig. 41.2 ). In addition, as parenchymal injury progresses, some of the cysts may enlarge and lymphoid aggregates may form solid nodules. Ultimately, the gland atrophies with fibrosis and fat deposition, which imparts a heterogeneous appearance on imaging ( Fig. 41.3 ). The strictures that form in the salivary ducts can be depicted via sialography and may have a string of beads appearance ( Fig. 41.4 ).




Figure 41.1


Summary illustration of the progression of parotid gland changes in Sjögren syndrome. Initially, the parotid glands in Sjögren syndrome may appear normal (A). Eventually, a classic miliary pattern of tiny cysts forms within the glands bilaterally, which appears as punctate foci of hypoattenuation on computed tomography (CT) and high signal on T2-weighted magnetic resonance imaging. The glands may be asymmetrically swollen (B) or normal in size (C). Ultimately, the gland atrophies with fibrosis and fat deposition (D). Along the way, punctate calcifications may appear within the parotid glands, which are a classic feature of intermediate to late stages of Sjögren disease and are best depicted on CT (E). In addition, as parenchymal injury progresses, some of the cysts may enlarge and lymphoid aggregates may form solid nodules. Given the autoimmune nature of Sjögren syndrome, patients are at risk for certain lymphomas, particularly non-Hodgkin lymphoma of the head and neck (F).

Jun 26, 2019 | Posted by in NEUROLOGICAL IMAGING | Comments Off on Sjögren Syndrome
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