Transcript Parotid Masses

Multimodality Imaging Overview
of Common and Uncommon
Solid Parotid Space Masses
eEdE-139
Whitney Finke, MD, Nicholas Koontz, MD,
Stephen Kralik, MD
Department of Radiology & Imaging Sciences
Indiana University School of Medicine
Indianapolis, IN
Disclosures
• None
Abbreviations
•
•
•
•
•
•
•
BMT = Benign Mixed Tumor
• T2WI = T2 weighted image
CECT = Contrast enhanced CT • Tx = Treatment
DCF = Deep cervical fascia
• +C = Contrast enhanced
EAC = External auditory canal
FS = Fat-saturated
MMT = Malignant Mixed Tumor
NECT = Non-contrast enhanced
CT
• PNT = Perineural tumor
• SCM = Sternocleidomastoid
• T1WI = T1 weighted image
Purpose
• Provide a comprehensive overview of imaging
characteristics of pathology-proven common &
uncommon solid parotid space masses
• Modalities
• US
• CT
• MRI
• FDG-PET/CT
Approach/Methods
• We performed a HIPAA-compliant retrospective
review of our institution's electronic medical
record (radiology and pathology databases) for
illustrative cases of histopathologically-proven
parotid masses
• Included cases with multimodality imaging
when possible
• Additionally, a review of the current medical
literature was performed
Findings/Discussion
• Introduction
• Anatomy
• Parotid space masses
With permission of Amirsys-Elsevier
Introduction
• Largest salivary gland
• Superficial “lobe”
• 80% of glandular volume
• Superficial to the plane of facial nerve
• Overlies ramus and angle of mandible, superficial to
masseter
• Deep “lobe”
• 20% of glandular volume
• Medial extent through stylomandibular tunnel
Parotid Space Anatomy
• Fascial investment
• Superficial layer DCF
(
)
• Bounderies
• Superior = EAC (
),
mastoid tip (
)
• Inferior = parotid tail,
below angle of mandible
between platysma &
SCM
• Medial = parapharyngeal
(
) & carotid (
)
spaces
• Anterior = masticator
space (
)
With permission of Amirsys-Elsevier
Parotid Space Contents
• Glandular tissue
• Parotid ducts
• Facial nerve (
)
• External carotid artery
(
)
• Retromandibular vein
(
)
• Surrogate marker for
CN 7
• Lymph nodes (
)
• Primary nodal drainage
of ear, face, & scalp
With permission of Amirsys-Elsevier
Parotid Masses
• 80% of salivary gland masses
• 80% benign (adults)
• Pediatric masses higher rate of malignancy
• Staging of malignant parotid masses
• Weighted heavily based upon size
• Subdivided based upon local extension
• Skin
• Soft tissues
• Bone
• Lingual or facial nerve
• Nodal or distant metastases
Facial Nerve Involvement
• CN7 involvement is a
critical part of parotid
mass evaluation
• Invasion
• PNT
• CN7 origin
• Image from origin
nucleus to end organ
• Adenoid cystic most
common, but seen
with other malignancy
With permission of Amirsys-Elsevier
Perineural Tumor
a
b
Adenoid cystic carcinoma with PNT. (a) Axial T1WI +C FS shows enhancement along
intraparotid CN7 (
), extending along the auriculotemporal nerve (
)
connecting CN7 & V3. (b) Abnormal enhancement involves the mastoid segment of CN7
(
) at the stylomastoid foramen and CN V3 (
) in the masticator space.
Nodal and Distant Metastatic
Disease
•Nodes:
• Poor prognostic factor
• Mucoepidermoid is the
most common , but
seen with other
malignancy
•Distant Metastases:
• Very poor prognosis
• Evaluate lungs and
bone
Coronal CECT: Heterogeneously
enhancing parotid mass (
) with
nodal metastases (
)
Differential Diagnosis of
Primary Parotid Solid Masses
• Common Diagnoses:
• Benign Mixed Tumor
• Warthin Tumor
• Metastatic Nodal
Disease
• Less Common
Diagnoses:
• Mucoepidermoid
Carcinoma
• Adenoid Cystic
Carcinoma
• Malignant Mixed Tumor
• Acinic Cell Carcinoma
• Adenocarcinoma
• Ductal Carcinoma
Transverse grayscale ultrasound:
Benign mixed tumor
General Imaging Overview:
• Imaging is nonspecific.
• 80% benign
• 80% are benign mixed tumors.
• Look for clues to suggest malignancy such as
invasive margins, perineural spread, and
lymphadenopathy.
• FDG uptake does not always correspond with
tumor grading.
• Ultimately biopsy and excision are needed for
definitive diagnosis.
Benign Mixed Tumor
• AKA: Pleomorphic
Adenoma
• Pathology:
Interspersed epithelial,
myoepithelial, &
stromal cellular
components
• Tx: Surgical Resection
• Recurrence seen with
surgical seeding
• 15% malignant
transformation
Axial T2WI shows a boscillated,
hyperintense mass involving both the
superficial and deep lobes of the left
parotid gland.
Benign Mixed Tumor
• Most common salivary
gland tumor:
• 80% of parotid gland
tumors
• >80% involve the
superficial lobe
• <1% are multifocal
Axial T2WI: BMT in the deep parotid lobe
Image courtesy of R Wiggins
BMT Seeding PostParotidectomy
a
b
c
Recurrent BMT along the course of the parotid duct. (a) Axial T1WI, (b) Axial T2WI, (c)
Axial T1WI+C demonstrates T1 hypointense (
), T2 Hyperintense (
), mildly
enhancing masses along the parotid duct (
).
Malignant Mixed Tumor
• 2 Types:
• Carcinoma-ex-pleomorphic
adenoma: Malignant
degeneration of one of the
cell lines in a BMT.
• Carcinosarcoma: multiple
malignant cell lines (<70
reported cases)
• Patients present with a
rapidally enlarging, longstanding parotid mass.
• Early: Indistinguishable
from BMT
• Late: aggressive, infiltrating
parotid mass.
T1WI+C: homogenously enhancing
mass with invasion into the
stylomastoid foramen.
Malignant Mixed Tumor
a
b
Malignant mixed tumor with invasion into the masseter and
sternocleidomastoid muscle. (a) Longitudinal greyscale ultrasound
shows a hypoechoic parotid mass (
). (b) Axial CECT shows a
heterogeneous mass in the superficial parotid (
) with invasion into
the SCM (
) and masseter (
).
Warthin Tumor
• Smoking associated
• Arises from salivarylymphoid tissue
• 2nd most common benign
parotid tumor
• 2-10% of parotid tumors
• Most common parotid tail
mass
• 20% multifocal
• 30% cystic component
• FDG and Tc avid
• Tx: excision (<1%
malignant transformation)
Axial CECT: hyperenhancing masses
in the bilateral parotid tails.
Warthin Tumor
a
b
Warthin Tumors. (a) Longitudinal greyscale ultrasound shows a
hypoechoic, partially cystic mass in the parotid tail (
). (b) Axial
FDG-PET/CT in a different patient shows an FDG avid mass in the
parotid tail (
).
Mucoepidermoid Carcinoma
• Most common primary
parotid malignancy
• 30% salivary gland
malignancies
• 50% in parotid
• Most common salivary
gland malignancy in
children.
• 44% have nodal
metastases
• Tx: resection +
radiation, and possible
neck dissection
Coronal CECT: heterogeneously
enhancing, partially cystic mass in the
parotid tail
Mucoepidermoid Carcinoma
a
b
c
Mucoepidermoid carcinoma in patient with history of prior left superficial
parotidectomy for Warthin Tumor. (a) Axial T2WI shows a cystic mass in the parotid
bed that has invaded through the anterior wall of the EAC (
). (b) Axial T2WI
more inferiorly shows cystic masses in the residual superficial lobe and the deep lobe,
with characteristic T2 hypointense regions (
). (c) Axial T1WI+C shows
involvement of the deep parotid lobe (
).
Adenoid Cystic Carcinoma
• 2nd most common
parotid malignancy
• 2-6% parotid gland
tumors
• 33% present with facial
pain and/or paralysis
• Look for PNT along V3
or the facial nerve
• Metastasizes to the
lungs and bone.
• Tx: parotidectomy and
radiation.
• Poor long term
prognosis (up to 20 year
late recurrence)
Axial FDG-PET image shows an
increased radiopharmaceutical uptake
in the left parotid mass.
Adenoid Cystic Carcinoma
a
b
c
Adenoid cystic carcinoma of the deep lobe of the parotid gland, with extension into the
superficial lobe. (a) Axial T1WI shows a T1 hypointense mass (
). (b) Axial T2WI
shows a heterogeneous, primarily hyperintense mass (
). (c) Axial T1WI+C
shows enhancement of the mass (
). The irregular margins and infiltrative
appearance suggest a higher grade malignancy.
Acinic Cell Carcinoma
• 3rd most common primary
parotid malignancy
(~15%)
• 2nd most common pediatric
parotid malignancy.
• Indistinguishable from
other low grade
malignancies. May have
cystic areas.
• 3% bilateral.
• Tx: Excision and radiation
Axial CECT shows an ill-defined,
centrally necrotic and peripherally
enhancing mass within the left
parotid gland.
Acinic Cell Carcinoma
a
b
c
Acinic Cell Carcinoma (additional images from patient seen on previous slide). (a)
Transverse grayscale ultrasound shows a hypoechoic mass in the left parotid gland
(
). (b) Axial PET CT shows an FDG avid mass in the left parotid gland (
).
(c) Axial T1WI+C shows a peripherally enhancing mass with central necrosis that
involves the superficial and deep lobes of the parotid gland, and extends into the
stylomastoid foramen (
).
Adenocarcinoma NOS
•9% of total salivary
gland
malignancies.
• 28-50% are in
parotid
•Usually present
with painful, rapidly
enlarging mass
•Tx: Parotidectomy
and radiation
Axial T2WI shows an irregular T2
hyperintense mass in the superficial
and deep lobes of the left parotid
gland
Image courtesy of K Mosier.
Salivary Ductal Carcinoma
• Pathology: Similar to
invasive ductal carcinoma
of the breast.
• Uncommon, extremely
aggressive malignancy
• Perineural spread is
common
• Cervical nodal metastasis
in 70%
• Distant metastasis to
lung, bone, brain
Axial CECT shows an ill defined
enhancing mass in the superficial
and deep lobes of the left parotid
gland, with extension into the
stylomandibular tunnel
Salivary Ductal Carcinoma
a
b
Salivary ductal carcinoma. (a) Axial CECT shows an irregular, enhancing mass in the
superficial and deep lobes of the left parotid gland. (
). (b) Coronal CECT shows
enhancing cervical lymphadenopathy (
).
Squamous Cell Carcinoma
• Rare
• 0.1-0.5% parotid tumors
• 3-10% malignant parotid
tumors
• Squamous metaplasia
develops secondary to
chronic inflammation
• Must exclude metastatic
disease from skin
• Metastasizes to regional
nodes, lungs, and liver.
Axial CECT shows an ill defined
enhancing mass in the right parotid
gland with areas of necrosis. Patient
had a history of long standing
chronic sialadenitis
Non-Hodgkin Lymphoma
• Nodal:
• Primary nodal
• Systemic
• 1-8% involve parotid
• Primary parenchymal
• Mucosa associated
lymphoid tissue type
(MALT)
• Rare, 2-5% of parotid
malignancies
• Infiltrative mass
Axial T1WI shows an infiltrative
hypointense solid mass in the
superficial parotid.
Non-Hodgkin Lymphoma
a
b
c
Non-Hodgkin lymphoma. (a) Axial CECT demonstrates enlarged nasopharyngeal
lymphoid tissue (
) and enlarged and necrotic intraparotid lymph nodes (
).
(b & c) Coronal CECT demonstrate enlarged and necrotic cervical lymphadenopathy
(
). The necrotic appearance of the lymph nodes suggests an aggressive vs.
partially treated lymphoma.
Intraparotid Nodal Metastases
• 4% of all parotid
neoplasms
• 1st order nodal station for
skin SCC and melanoma
from scalp, ear, and face.
• Systemic metastases are
rare.
• Evaluate for
extracapsular extension
and perineural spread.
Axial CECT shows abnormally
enlarged intraparotid lymph nodes.
Intraparotid Nodal Metastases
a
b
c
Melanoma Nodal Metastases. (a) Axial T1WI image shows multiple abnormally
enlarged right intraparotid lymph nodes (
). (b) Axial NECT and (c) Axial FDG
PET images show enlarged (
) FDG avid (
) right intraparotid lymph nodes.
Conclusion:
• Imaging is nonspecific.
• Look for clues such as invasive margins,
perineural spread, lymphadenopathy, and
multifocality.
• 80% benign
• 80% are benign mixed tumors.
• Invasive margins suggest a more aggressive
tumor.
• Ultimately biopsy and excision are needed for
definitive diagnosis.
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