Other / Other / MRI

Sialosis (sialadenosis)

Sialosis (sialadenosis) presents as diffuse, non-inflammatory, non-neoplastic recurrent or persistent enlargement of major salivary glands, typically the parotid, caused by acinar hypertrophy in patients with systemic disease.
Look For First
  • Bilateral symmetrical enlargement of parotid glands on imaging
  • Hyperechoic appearance without focal lesions on ultrasound
  • Sparse peripheral ducts on sialography with normal gland density on CT
Key Image Findings
  • Ultrasound shows enlarged, hyperechoic salivary glands bilaterally without focal lesions or increased blood flow.
  • CT demonstrates normal or enlarged glands with normal density throughout most of the disease course.
  • Sialography reveals sparse peripheral ducts, reflecting the diffuse acinar hypertrophy.
  • Diabetic sialadenosis shows greater fatty infiltration on CT, while alcoholic sialadenosis demonstrates reduction of fatty tissue.
  • End-stage glands may appear diffusely dense and enlarged on CT.
  • The glands maintain their overall structural integrity without features of inflammation, neoplasm, or ductal obstruction.
Differential Diagnosis
  • Sjögren syndrome: presents with autoimmune inflammation, positive serology, and acinar destruction rather than hypertrophy
  • Sarcoidosis: often shows enhancement and associated systemic findings with granulomatous features
  • Lymphoma: typically focal or asymmetric with mass effect and altered enhancement patterns
  • Sialadenitis: acute inflammation with ductal dilation, edema, and increased blood flow on color Doppler
  • Recurrent parotitis: history of acute episodes with ductal strictures and parenchymal scarring
Discussion

Diabetes mellitus accounts for approximately 50% of sialosis cases, making it the most common identifiable cause.

Alcohol use and diabetes are the two most frequent etiologies, though some cases remain idiopathic.

The pathophysiology involves hypertrophy of acinar components rather than true neoplastic growth or inflammatory changes.

Sialosis is characterized by the absence of ductal obstruction, ductal dilation, or parenchymal inflammation on imaging.

The imaging appearance varies by underlying etiology: fatty infiltration predominates in diabetes while fatty tissue reduction occurs in alcoholic sialadenosis.

Multiple systemic conditions including endocrine, metabolic, gastrointestinal, and neurogenic disorders can precipitate sialosis.

Reporting Pearls

Describe as 'bilateral, symmetrical salivary gland enlargement with preserved normal gland density and architecture, without ductal dilation or focal lesions, consistent with sialadenosis' and note the etiology-specific features (fatty infiltration in diabetes versus fat reduction in alcohol use) when identifiable.

Pitfalls
  • Mistaking sialadenosis for Sjögren syndrome due to bilateral gland enlargement; key distinction is the absence of autoimmune inflammation and preservation of gland structure in sialosis.
  • Confusing sparse peripheral ducts on sialography with ductal obstruction or stricture disease.
  • Overlooking the etiologic features on CT that hint at underlying systemic disease (e.g., fatty infiltration suggesting diabetes).
  • Assuming bilateral salivary gland enlargement is always neoplastic or inflammatory rather than considering systemic metabolic or endocrine causes.
Source: Reference source

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