This document discusses pleomorphic adenoma, the most common benign tumor of the salivary glands. It typically presents as a slow-growing, painless mass in the parotid gland. Other key details include: - It represents about 60% of parotid tumors and occurs most often in females ages 30-60. - On imaging, it appears as a well-defined mass that is hypoechoic on ultrasound and enhances with contrast on CT/MRI. - The facial nerve must be carefully preserved and dissected during surgery to remove these tumors from the parotid gland in order to prevent facial paralysis.

1. RADIOLOGY II:
HEAD & NECK
GROUP 3
MARTINEZ, MENDOZA, MIÑA, MONDARTE, MUSA

2. CASE III
40 y/o, Female with a painless left cheek mass
Pleomorphic Adenoma
Primary Working Impression
● 3rd to 6th decades of Life
● Female > Male (2:1)
● Painless mass on one side of the face
● Ovoid, well-defined, hypoechoic mass lesion

3. Differential Diagnosis
Differentials Rule In Rule out
Pleomorphic adenoma -benign, well-circumscribed round mass
-painless, slowly progressing swelling
-<6 cm in diameter
-lesions arise in the parotid gland (superficial lobe)
-fibrillary stroma, mixture of myoepithelial cells,
ductal cells and extracellular stroma
-female > male (2:1)
Warthin Tumor
(Papillary
Cystadenoma
Lymphomatosum)
-benign, well circumscribed round mass
-painless, slowly progressing swelling
-2 to 5 cm in diameter
-may arise within the superficial lobe of parotid
gland
-epithelial and lymphoid tissue
-lymphoid origin
- most commonly arise from
the parotid tail
-hypercellular microcysts
-more common in males
Mucoepidermoid
Carcinoma
-painless swelling
-lesions arise in the parotid gland (60-70%)
-low-grade tumors: well-circumscribed masses, 2
to 3 cm in diameter at initial discovery
-most common in middle age
-malignant (most common
primary malignant tumor of
salivary glands)
-high grade tumors: ill-defined
margins

4. Differential Diagnosis
Differentials Rule In Rule out
Myoepithelioma -benign tumor
-3 to 5 cm in diameter
-site of occurrence: parotid gland
-contain (nearly) exclusively myoepithelial cells
-rare (1% )
-ductal (epithelial) component is
scant or absent
Adenoid Cystic
Carcinoma
-most common single site of origin: parotid
gland (25%)
-ductal and myoepithelial cells
-malignant (2nd most common)
-minor salivary glands constitute
the majority of ACCs (60%)
-ill-defined mass with perineural
spread and local invasion
-tend to present at an older age
(5th–7th decades of life)
Acinic Cell
Carcinoma
-well-circumscribed
-painless, homogeneously enhancing,
slow-growing mass
-lesions arise in the parotid gland (90%)
-malignant
-most commonly located in the
parotid tail
-bilateral and multifocal

5. Pleomorphic Adenoma
● Mostly presents as a solitary mobile slow-growing, painless mass
● The etiology is unknown
● Occurs in ALL ages (MC: 3rd-6th decades of life)
● Female > Male (2:1)
● Parotid gland: 84%
● Submandibular gland: 8%
● Minor salivary glands: 6.5%

6. Salivary gland neoplasms
● represent less than 2% of all tumors in humans
○ about 65% to 80% arise within the parotid
■ majority of parotid tumors are benign

7. Most Common Benign Tumor: PLEOMORPHIC ADENOMA
- most common salivary gland neoplasms
- represent about 60% of tumors in the parotid
- “mixed tumors” (consist of a mixture of ductal (epithelial), myoepithelial, and
mesenchymal cells
- rounded, well-demarcated masses that rarely exceed 6 cm in greatest
dimension
- painless, slow-growing, mobile, discrete masses within the parotid

9. Most Common Benign Tumor: WARTHIN TUMOR
(PAPILLARY CYSTADENOMA LYMPHOMATOSUM)
· - second most common salivary gland neoplasm
- arises almost exclusively in the parotid gland.
- more commonly in males
- fifth to seventh decades of life
- risk factor: smokers
- most are unifocal, but about 10% are multifocal and 10% bilateral
- round to oval encapsulated masses, 2 to 5 cm in diameter, and readily
palpable within the superficial parotid gland

10. Most Common Malignant Tumor: MUCOEPIDERMOID
CARCINOMA
·
- most common primary malignant tumor of salivary glands
- representing about 15% of all salivary gland tumors
- most (60% to 70%) occur in the parotids
- with variable biological aggressiveness that is composed of a mixture of
squamous and mucous cells
- can grow as large as 8 cm in diameter

11. Expected Radiographic Findings
On all modalities, these tumors typically appear as rounded masses with
well-defined, "bosselated" or "polylobulated" borders (many small undulations, not
truly lobulated). They are most commonly located within the parotid gland,
particularly the superficial lobe.
When they arise from the deep lobe of the parotid they can appear entirely extra
parotid, seen in the prestyloid parapharyngeal space, without a fat plane between
it and the parotid, and widen the stylomandibular tunnel. Pleomorphic adenomas
can also arise from salivary rest cells in the parapharyngeal space itself without
connection to the parotid gland.

12. Expected Radiographic Findings
The parapharyngeal space, also known as the
prestyloid parapharyngeal space, is a deep
compartment of the head and neck around which
most other suprahyoid fascial spaces are arranged.
It consists largely of fat, neurovascular structures,
and, in some definitions, the retromandibular part of
the deep lobe of the parotid gland.

13. Expected Radiographic Findings
The stylomandibular tunnel is a space
between the mandibular ramus and the
styloid process / stylohyoid ligament. It
separates the (prestyloid) parapharyngeal
space from the parotid space. In some
definitions, the portion of the parotid gland
that extends into the stylomandibular tunnel
is considered the deep (retromandibular)
portion of the gland

14. ULTRASOUND
They are typically hypoechoic and may show posterior acoustic enhancement.
Ultrasound is also useful in guiding a biopsy (both FNAC and core biopsies) but
needs to be carried out with care to avoid facial nerve damage

15. CT
When small, they have homogeneous attenuation and prominent enhancement.
When larger, they can be heterogeneous with less prominent enhancement, foci of
necrosis, and possible delayed enhancement. Small regions of calcification are
common

16. MRI
The signal characteristics are homogeneous when the tumor is small. Larger tumors may be
heterogeneous.
T1: usually of low intensity
T2
● characteristically of very high intensity (especially myxoid type) 6
● often have a rim of decreased signal intensity on T2-weighted images representing the surrounding
fibrous capsule
T1 C+ (Gd): usually demonstrates homogeneous enhancement

17. What structure is preserved and dissected carefully during parotidectomy?
Treating parotid gland tumors requires great precision
on the part of your surgical team because the facial
nerve is nearby. Loss of facial nerve function related to
the treatment of the parotid gland tumor can result in
partial or total paralysis on one side of the face. This
can greatly impair a person’s ability to make basic
movements of the face, such as raising the eyebrows,
closing the eyes, or smiling. It can be accompanied by
vision loss and possibly difficulty eating or speaking.

18. References…
Bokhari MR, Greene J. Pleomorphic Adenoma. [Updated 2022 Jul 4]. In:
StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-.
Available from: https://www.ncbi.nlm.nih.gov/books/NBK430829/
Kessler, A. T., &amp; Bhatt, A. A. (2018). Review of the major and minor salivary
glands, part 2: Neoplasms and tumor-like lesions. Journal of Clinical Imaging
Science, 8, 48. https://doi.org/10.4103/jcis.jcis_46_18
Kumar, V., Abbas, A. K., & Aster, J. C. (2017). Robbins Basic Pathology (10th ed.)

19. Thank you for listening