Adenoid cystic carcinoma of the salivary glands

Last revised by Henry Knipe on 15 Sep 2021

Adenoid cystic carcinoma of the salivary glands is the second most common malignancy involving the minor salivary glands behind mucoepidermoid carcinoma and the second most common malignancy involving the parotid gland.

Adenoid cystic carcinomas arise more commonly in the minor salivary glands (~55%) than in the major salivary glands. They are the most common sinonasal tumors of salivary origin. They are locally aggressive with a propensity for perineural spread 5

Generally, a distinction is made radiologically between low-grade and high-grade adenoid cystic carcinomas. Low-grade tumors tend to be well-defined, in contradistinction to high-grade tumors, which appear infiltrative. However, both subtypes are usually homogeneously enhancing after contrast administration.

Adenoid cystic carcinomas are frequently associated with perineural spread (via cranial nerve VII), which is well appreciated on MRI.

  • T1: hypo- to isointense
  • T2: slightly hyperintense, with higher grades being markedly hypointense 6
  • T1 C+ (Gd): homogeneous enhancement

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