Author:
Katya Shpilberg |
Grayscale Ultrasound | Doppler | CT | MRI - T1 | MRI - T2 | MRI - postcontrast T1 | Gross Pathology | Histology | Additional comments or images |
Benign neoplasms: | |||||||||
Pleomorphic adenoma |
hypoechoic, well-defined, lobulated
w/ posterior acoustic enhancement; +/- calcs Image 1 Image 2 |
peripheral vascularity w/ hypovascular center typical |
variable enhancement typically gradually progressive & avid;
+/- calcifications
Image 1 Image 2 (delayed) |
uniformly hypointense when small, low to intermediate signal when large; may have a capsule Image 1 Image 2 |
uniformly hyperintense when small, intermediate to high signal when large; may have a capsule Image 1 Image 2 Image 3: ADC (high ADC value helps differentiate from malignant neoplasms) |
variable enhancement typically gradually progressive
& avid; infiltration into parapharyngeal space, muscles & bone may indicate capsule rupture or malignant transformation Patient 1 Patient 2: early Patient 2: delayed |
soft tan lobules representing epilial component interspersed among lobulated firm, white, gritty chondromyxoid component; fibrous capsule. | admixture of epilial & chondromyxoid elements | MC benign parotid neoplasm; middle-aged women; unilateral & solitary; superficial lobe; lobulated shape/ bosselated contour; post-op seeding may occur; may undergo malignant transformation after decades. |
Warthin tumor (cystadenoma lymphomatosum) |
oval, hypoechoic, well-defined;
+/- multiple anechoic areas; may appear as simple cyst Image 1 Image 2 |
often hypervascularized but may contain only short vessel segments | strong, uniform enhancement; +/- central cystic or necrotic areas +/- washout |
Image 1: hypointense, well-circumscribed, homogeneous, cystic or solid
Image 2 |
Image 1: well-circumscribed; variable signal but typically hyperintense (atypical image shows hypointense)
Image 2 |
typically uniform enhancement; peaks early +/- washout; can have central non-enhancing cystic area.
Image 1 Image 2 Image 3 |
encapsulated, soft, ovoid w/ smooth, lobulated surface; tan tissue w/ cystic spaces that contain mucoid, brown or thin, yellow fluid | double layer of oncocytes (epithilial cells) resting on a dense lymphoid stroma | incr upt on T99m pertechnetate, FDG-PET, & thallium-201 chloride scans 2nd MC benign neoplasm in adults; elderly men; b/l in up to 10%; often multiple; parotid tail; associated w/tobacco; no malignant potential |
Infantile hemangioma (capillary hemangioma) | discrete intraparotid masses or diffuse infiltration; enlarged gland w/altered echogenicity. | variable increase in flow; can be very hypervascular | well-defined mass w/ uniform, intense enhancement; may contain phleboliths. | typically low to intermediate signal w/ flow voids | typically hyperintense w/ flow voids | intense enhancement including of flow voids | lobules of capillaries w/ evidence of cellular proliferation | clusters of plump endothelial cells, pericytes & mast cells; frequent mitotic figures; multi-laminated endolial basement membrane | MC benign pediatric salivary gland mass;
enlarges in 1st yr of life; F
> M; may spontaneously regress. Angiography: hypervasc mass w/ dense, prolonged capillary blush; enlarged feeding & draining vessels; no true AV shunting |
Lipoma | oval & hypoechoic w/ sharp margins; compressible; hyperechoic linear structures regularly distributed in striated or feathered pattern | only single vessel segments may be found | well-defined mass of uniform fat-density; no enhancement; significant enhancement should raise concern of liposarcoma. | markedly hyperintense; signal suppression on fat-saturated MR sequences | mildly hyperintense; signal suppression on fat-saturated MR sequences | no enhancement; significant enhancement should raise concern of liposarcoma | encapsulated, smooth or lobulated, soft yellow masses | mature adipocytes that are uniform in size & shape; occasional fibrous connective tissue septations | |
Neurofibroma | ovoid, well-demarcated, homogeneous; +/- multiple small cystic areas; lobulated & infiltrating if plexiform | ovoid, well-demarcated, homogeneous; isodense; +/- multiple small cystic areas; moderate enhancement; marked enhancement if plexiform. | low to intermediate signal intensity; +/- heterogenous areas of different signal intensities | high signal intensity; +/- heterogenous areas of different signal intensities | moderate enhancement; marked enhancement if plexiform | loose connective tissue fibers randomly distributed among tapering nerve fibers | may arise from intraparotid facial nerve trunk in NF1; difficult to distinguish from pleomorphic adenomas outside clinical context | ||
Angiolipoma |
Image 1: Noncontrast. Circumscribed mass
w/ fat & soft tissue density components
Image 2: Contrast-enhanced. marked enhancement around fatty components |
heterogenous w/ markedly hyperintense components due to fat | heterogenous | marked enhancement around fatty components | difficult to differentiate from hemangioma w/ fatty degeneration; infiltrating form is less common | ||||
Oncocytoma | small, well defined | small, well defined | small, well defined, hypointense to normal parotid gland | isointense to hyperintense to normal parotid gland | same enhancement as normal parotid gland | mitochondria-rich oncocytes | rare benign tumor; associated
w/ prior radiation; mimics lymph node on imaging. increased radiotracer uptake at technetium pertechnetate scan. |
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Schwannoma | well-defined oval mass in superficial lobe; often contains anechoic areas | well-defined oval mass in superficial lobe; enhances. | well-defined oval mass in superficial lobe | target appearance w/ peripheral lower T2 signal | enhances | originates from facial nerve; target-appearance on T2 is highly suggestive | |||
Malignant neoplasms: | |||||||||
Features characteristic of all malignancies | high vascularization, high systolic peak flow velocity and/or increased intratumoral vascular resistance index may indicate malignancy but are non-specific | Ill defined margins suggest higher grade | Ill defined margins suggest higher grade. |
T2: lower T2 signal is a reasonably reliable predictor of malignancy ADC. Malignancies may demonstrate diffusion restriction/lower ADC signal than benign neoplasms |
deep infiltration into parapharyngeal space, muscles & bone strongly suggest malignancy; Best study to determine perineural spread | Imaging findings of parotid malignancies are largely nonspecific and true diagnosis typically requires tissue sampling | |||
Mucoepidermoid carcinoma | smooth margins & large cystic areas when low-grade, more solid than cystic areas when high-grade | See typical malignancy features above |
smooth margins when low-grade; +/- calcs; no significant enhancement when low grade, more solid homogeneously enhancing areas
w/ increasing grade.
Image 1 Image 2 |
smooth margins when low-grade; hypo- to isointense |
hyperintense
w/ smooth margins when low grade; intensity decreases w/ higher grade
Image 1 Image 2 |
no significant enhancement when low-grade; more solid homogeneously enhancing areas w/ increasing grade. | gray, tan-yellow, or pink | squamous & mucous cells arranged in cords, sheets, or cystic configurations (image of high grade) | most common malignant salivary gland neoplasm in children; most common parotid malignancy in adults; may show several levels of differentiation; low grade resembles pleomorphic adenoma & high grade Warthin's tumor on imaging so aspiration/biopsy is needed; prognosis depends on tumor grade |
Adenoid cystic carcinoma | See typical malignancy features above | typically enhance | low to intermediate signal intensity | moderate signal intensity; high grade tend to be lower in signal intensity | solid enhancement; tendency for perineural spread (on CN 7 +/- CN 5) manifested as enhancement (image w/ perineural spread) | pink or tan w/ mottled surface; rarely necrotic change; infiltrative margins; no capsule | Three distinct histological patterns: cribriform, tubular & solid; tumor may have one, two or three of these | 2nd MC parotid malignant neoplasm in adults; slow growing; late metastases; favorable prognosis | |
Malignant mixed tumor (carcinoma ex-pleomorphic adenoma) | See typical malignancy features above |
Typically enhance. Axial Coronal |
typically hypointense | typically low to intermediate signal intensity | typically enhance | result from malignant transformation of long-standing pleomorphic adenoma; poor prognosis | |||
Acinic cell carcinoma | may be well-defined w/ regular margins; can be associated w/ mandibular destruction | See typical malignancy features above | typically enhance | typically hypointense; can be well-defined | typically low to intermediate signal intensity; can be hyperintense. |
Image 1: early enhancement
Image 2 (delay): washout typical |
may present as multiple painless masses; favorable prognosis | ||
Adenocarcinoma | often associated w/ locoregional lymphadenopathy | See typical malignancy features above | typically enhance | typically hypointense | typically low to intermediate signal intensity | typically enhance | poor prognosis | ||
Squamous cell carcinoma | See typical malignancy features above | typically enhance | typically hypointense | almost always hypointense | typically enhance | can arise de novo or from extranodal spread; poor prognosis | |||
Undifferentiated (ductal) carcinoma | See typical malignancy features above | typically enhance | typically hypointense | typically low to intermediate signal intensity | typically enhance | no specific imaging features; very poor prognosis | |||
Metastases | metastatic lymph nodes may be well-defined & oval/ round; inhomogeneous echotexture w/ loss of fatty hila suggest metastatic disease (image of adenoca) | typically increased vascularity (Image of metastatic melanoma) |
Image 1 (axial): variable appearance depending on primary neoplasm
Image 2 (coronal) |
variable appearance depending on primary neoplasm (image of melanoma mets) | variable appearance depending on primary neoplasm (image of melanoma mets) | variable appearance depending on primary neoplasm (image of melanoma mets) | adenopathy more common than direct mets; usually paraglandular in location; typically from locoregional spread from scalp, external auditory canal or cheek skin squamous cell carcinoma or melanoma; systemic mets rarely involve parotid but can result from melanoma, breast ca, lung ca & rarely RCC | ||
Lymphoma | discrete hypoechoic mass; may be multiple; may present as diffuse infiltration characterized by an enlarged gland w/ altered echogenicity | demonstrate increased flow | mild to moderate homogeneous enhancement; central necrosis may be present; focal masses confined to intraparotid lymph nodes or diffuse parotid infiltration. | homogeneous intermediate signal intensity | homogeneous intermediate signal intensity; more conspicuous on STIR; central hyperintensity if necrosis is present | mild to moderate homogeneous enhancement, central necrosis may be present | well-circumscribed, encapsulated, soft, fleshy masses | sheets of lymphoid cells arranged in diffuse or follicular pattern; furr subdivided into small cleaved & large cell variants |
foci of increased activity on FDG-PET
& 67-Gallium scans (image of PET-CT)
MALToma when primary; secondary salivary gland involvement by lymphoma is MC in parotids; NHL >> Hodgkin's |
Rhabdomyosarcoma | cannot define full extent of mass | variable enhancement; indistinct margins; isodense to muscle; heterogenous; bony erosion. | isointense; high signal foci due to hemorrhage in ~30% | heterogenously hyperintense | enhances diffusely; infiltrating appearance w/ indistinct margins | pink-gray mass w/ frequent areas of hemorrhage & necrosis; may be grape-like (sarcoma botryoides) | undifferentiated “blue cells” w/ scant cytoplasm & primitive-appearing nuclei | most common pediatric soft tissue sarcoma; parotid involved by direct extension; perineural spread is common; FDG-avidity on PET has been observed. | |
Leukemia | diffuse enlargement w/ altered, variable echogenicity | increased blood flow | variable attenuation & enhancement | variable signal intensity | variable signal intensity | variable enhancement | indistinguishable from or causes of parotid gland enlargement, including infiltrative lymphoma | ||
Infectious/Inflammatory lesions: | |||||||||
Parotitis | enlarged & inhomogeneous gland w/ multiple small, oval, hypoechoic areas | increased blood flow | diffuse enhancement w/ low-attenuating foci | slightly hypointense | slightly hyperintense | may demonstrate marked enhancement | most common parotid disease in children; usually viral (mumps); can result from obstructing sialolithiasis | ||
Abscess | hypoechoic or anechoic w/ posterior acoustic enhancement & unclear borders; +/- echogenic rim; +/- moving debris and/or hyperechoic foci of gas | peripheral enhancement, often irregular; low-attenuation collection. | hypointense, particularly in its central aspect | hyperintense, particularly in its central aspect | peripheral enhancement, often irregular | restricted diffusion is typical, particularly in its center; usually bacterial. | |||
Benign-lymphoepilial lesions- HIV | numerous small, hypoechoic or anechoic lesions throughout enlarged gland | no internal enhancement of small cystic lesions; bilateral gland enlargement w/ intraglandular small cystic masses; some masses maybe hyperdense due to protein/ hemorrhage. | bilateral gland enlargement w/ intraglandular small hypointense cysts; hyperintense proteinaceous/ hemorrhagic cysts may occur | bilateral gland enlargement w/ intraglandular small hyperintense cysts | no internal enhancement of small cystic lesions | intranodal cyst lined w/ epilial cells | characteristic HIV lesions; associated w/ cervical lymphadenopathy & enlarged adenoids; may present as multiple painless masses | ||
Tuberculosis | focal, intraparotid, nearly anechoic zones that might have a cavity or cavities | no color flow in necrotic caseous cavities | gland enlargement w/ calcification; may contain hypodense areas; often b/l; +/- peripheral enhancement reflecting an abscess. | can have peripheral enhancement reflecting an abscess | parotid is most commonly involved salivary gland w/ TB; typically results from extension of cervical adenopathy | ||||
Sjogren syndrome | inhomogeneous echotexture w/ scattered multiple, usually well-defined, small, oval, hypoechoic or anechoic areas | increased parenchymal blood flow | heterogenous enhancement of enlarged gland; ranges from normal appearance to glandular enlargement w/ variable attenuation; hypointense areas indicate cystic changes & fat deposition; atrophic gland in late stages | enlarged heterogenous-appearing gland; “salt & pepper” or “honeycomb” appearance when advanced |
enlarged glands containing multiple hyperintense cysts; duct destruction best seen on heavily T2-weighted MR sialogram
Image 1 Image 2: MR Sialogram |
heterogenous enhancement of enlarged gland | lymphocytic infiltrate is seen in association w/ destruction of parotid gland tissue;; Title: From Education Exhibit "Swelling at Angle of Mandible: Imaging of Pediatric Parotid gland & Periparotid Region |
intraglandular contrast pooling can be seen on conventional sialogram
Increased risk of salivary gland lymphoma (typically aggressive) |
|
Sarcoid | single or multiple hypoechoic areas in an enlarged or normally sized gland; may be manifested as diffuse low echogenicity | blood flow may be increased |
multiple benign-appearing, non-cavitating masses; often bilateral; may contain calcifications;
gland may be enlarged
heterogenous enhancement of gland; gland may be enlarged |
multiple benign-appearing, non-cavitating masses; often bilateral; gland may be enlarged | multiple hyperintense benign-appearing, non-cavitating masses; often bilateral; gland may be enlarged | heterogenous enhancement of gland; gland may be enlarged | confluent, non-necrotizing epilioid granulomas |
increased uptake on Gallium-67 scan
parotid gland involved in ~30% |
|
Langerhans cell histiocytosis | diffuse enlargement & hypoechogenicity of gland | hyperenhancement of enlarged glands; bilateral homogenous gland enlargement; no necrosis or calcification. | bilateral homogenous gland enlargement | bilateral homogenous gland enlargement | hyperenhancement of enlarged glands | pediatric population; can be first manifestation of disease | |||
Amyloidosis | can cause diffuse gland enlargement | can cause diffuse gland enlargement | can cause diffuse gland enlargement | can cause diffuse gland enlargement | very rare | ||||
Congenital/ miscellaneous lesions: | |||||||||
Lymphangioma (lymphatic malformation) | multicystic w/ thin septations; solid elements may be present | typically no flow or than in septations | multi-lobulated w/ septations & cystic areas; may contain fluid-fluid levels; typically does not enhance; solid elements may enhance. |
Image 1: multilobulated, predominantly hypointense; multiple fluid-fluid interfaces
w/ variable signal intensity due to hemorrhage of different age Image 2 |
multilobulated, predominantly hyperintense; multiple
fluid-fluid interfaces w/ variable signal intensity due to
hemorrhage of different age
Image 2 Image 3 |
Image 1: typically does not enhance; solid elements may enhance.
Image 2 |
smooth, gray, glistening, non-encapsulated mass | dilated endolial-lined lymphatic spaces; internal septations w/ varying thickness; may have dilated, thin-walled vessels w/in mass | 65% present at birth, 90% detected by age 2; can be trans-spatial; may be complicated by infection or hemorrhage |
Venous malformation | multilobulated; loculations w/ possible fluid levels; compressible; hyperechoic shadowing structures reflect phleboliths | venous flow may be observed & augmented by compression w/ transducer | multilobulated; loculations w/ possible fluid levels; +/- phleboliths; +/-remodeling of adjacent bone & fat hypertrophy; variable enhancement, may be delayed; enlarged draining veins may be seen. | multilobulated; loculations w/ possible fluid levels; hypertrophy of adjacent fat | lesions w/ large vascular channels appear cyst-like, hyperintense, septated; lesions w/ smaller vascular channels appear more solid & intermediate in signal intensity (image of T2*/GRE) | enhancement is variable in intensity & homogeneity; enlarged draining veins may be visualized; may have delayed enhancement. | poorly circumscribed conglomeration of venous channels | venous channels that vary in luminal diameter & wall thickness; lined by flat, mitotically inactive endolium & scant mural smooth muscle; absent internal elastic lamina; luminal thrombi; phleboliths | phleboliths may be seen on plain films; often trans-spatial. |
First branchial cleft cyst | typically anechoic; may contain internal echoes due to hemorrhage/ protein | demonstrates no flow | no internal enhancement; slight enhancement of capsule | hypointense w/ possible regions of increased signal due to hemorrhage/ protein | hyperintense | no internal enhancement; slight enhancement of capsule | usually contains thick mucous | thin outer layer of fibrous tissue forms a pseudocapsule; inner layer of flat squamoid epilium; germinal centers & lymphocytes may be present in cyst wall | type 1: preauricular or intraparotid,
+/- sinus tract to middle ear or medial EAC type 2: posterior or inferior to angle of mandible, +/- sinus tract to lateral EAC |
Cyst | anechoic w/ posterior acoustiic enhancement, imperceptible wall & well-defined margins | avascular | fluid attenuation, or uniformly hyperdense due to protein/ hemorrhage; no internal enhancement; +/- faint peripheral enhancement | hypointense; may be hyperintense due to protein/ hemorrhage | Hyperintense | no internal enhancement; may demonstrate faint enhancement along periphery | uncommon; can be congenital or acquired; pseudocysts w/ fibrous lining may also occur | ||
Sialolithiasis |
echogenic; can have posterior acoustic shadowing
Image 1 Image 2 |
Image 1: very hyperdense since typically calcified
Image 2 |
markedly hypointense; detection facilitated by use of heavily T2-weighted MR- sialogram | frequently can be seen on plain films (image of conventional sialogram). ~4 times less common than in submandibular gland; increased incidence w/ strictures; produces dilatationof Stenson duct if obstructive; may result in inflammatory changes & cause parotitis. | |||||
Sialocele | anechoic; can contain echogenic debris | avascular | typically hypodense unless contains hemorrhagic/ proteinaceous products; does not enhance. | typically hypointense unless contains hyperintense hemorrhagic/ proteinaceous material. | hyperintense; heavily T2-weighted MR-sialogram deminstrates communication w/ parotid duct | does not enhance | opacifies on conventional sialogram since communicates w/ parotid duct. usually post-traumatic, particularly penentrating trauma. | ||
Sialosis | bilateral gland enlargement | bilateral gland enlargement; slightly greater than normal density | bilateral gland enlargement | bilateral gland enlargement; slightly higher than normal signal | painless, usually symmetric; caused by DM, hypothyroidism, alcoholism, obesity, starvation & some medications (phenothiazines & several diuretics); may resolve if underlying cause resolves | ||||