parotid lipoma

Parotid lipomas are rare benign non-epithelial salivary gland neoplasms. They show the characteristic imaging features of fat-containing lesions and resemble lipomas that can occur elsewhere in the body.


Parotid lipomas account for 0.6-4.4% of documented benign parotid tumors. Mean age at manifestation of lipoma is more than 50 years and they demonstrate a predisposition for male gender.

Risk factors

Parotid lipomas may be related to :

  • chronic alcoholism
  • malnutrition with hormonal/metabolic irregularities
  • medication

Clinical presentation

Facial swelling, facial outline deformity and sometimes facial nerve palsy.


Parotid lipomas are well-defined soft tissue lesions, usually encapsulated, and comprised primarily of fat. Any non-adipose segments must be carefully evaluated to eliminate a more aggressive element.


Indicates mature adipocytes with no cellular atypia or isomorphism. A thin fibrous capsule encircling a tumor of mature similarly sized adipocytes. Tumor capsule detection may benefit in differentiating such a neoplasm from lobular lipomatous atrophy and pseudolipoma all of which are non encapsulated .

Radiographic features

  • parotid lipomas are commonly well-circumscribed with parallel linear echogenic lines
  • variable appearance, hyperechoic to adjacent muscle and sometimes isoechoic or hypoechoic
  • lipomas retain the conventional features of homogeneous lesions with occasional septations
  • density of -50 to -150 HU
  • no post-contrast enhancement

MRI is the  modality of choice to visualize parotid neoplasms, giving the adequate soft tissue description and repeatedly enabling visualization of the tumor capsule from adipose tissue . Parotid lipomas demonstrate:

  • T1: high signal

  • T2: low signal

  • fat-suppressed T1W: complete suppression of signal as tumors of adipocytic lineage

Differential diagnosis

  • lobular lipomatous atrophy
  • pseudolipoma
  • oncocytic lipoadenomas
  • primary or metastatic parotid masses
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