MAJOR SALIVARY GLANDS Prof. Dr. SYED AMIR GILANI M.B;B.S (Pb) PhD (Swiss) Afro-Asian Institute of Medical Sciences Lahore, Pakistan.

• Longitudinal and transverse planes Examination Scan Planes • Longitudinal and transverse planes

Sonographic Anatomy and Normal Findings • Sonographic anatomy: The largest of the major salivary glands, the parotid gland is located anteroinferior to the ear and posterolateral to the ramus of the mandible.

Its excretory duct leaves the gland anterosuperior to the buccal mucosa. Generally the duct cannot be denned with ultrasound unless it is enlarged as a result of obstruction.

Topographic anatomy of the parotid gland

• Normal findings: All of the major salivary glands have smooth, sharp borders and a uniformly hyperechoic texture (similar to the thyroid gland).

a, b Oblique scan through the right parotid gland

Scanning Protocol Transducer: 7.5 MHz The patient is positioned supine, and a wedge may be placed beneath the shoulder. The neck is hyperextended and turned to the side.

• Parotid gland: surveyed in longitudinal and transverse scans (except for the retro- mandibular part of the gland) • Submandibular gland: The transducer is positioned lateral to the oral floor on each side. • Sublingual gland: The transducer is positioned lateral to the oral floor on each side.

Overview and Classification of Findings • Indication for sonography: As a rule, ultrasound is used specifically to distinguish between swelling and a tumor (see Peripheral Lymph Nodes,

Pathology • Sialoliths: 80 % of salivary stones occur in the submandibular gland and 20 % in the parotid gland. The gland may undergo secondary enlargement with a change of internal echo pattern.

• Sialadenitis: bacterial or viral (mumps) • Sialadenosis • Ductectasia. Stricture? • Tumors: 78 % are benign, 13 % malignant, 5 % metastatic

- Adenomas: pleomorphic adenoma (parotid mixed tumor, 85 %) - Adenomas: pleomorphic adenoma (parotid mixed tumor, 85 %). oncocytoma, Whartin tumor - Nonepithelial tumors - Secondary tumors (metastases, 5%)

Abnormal findings in the salivary glands Anechoic Isoechoic or enlarged Hypoechoic Hyperechoic Cysts Viral sialadenitis Acute bacterial sialadenitis Sialadenosis Abscess Chronic sialadenitis Parotid mixed tumor Lipoma, hemangioma, lymphangioma Pleomorphic adenoma Sialolithiasis Immunogenic sialadenitis Cystadenolymphoma

Abnormal findings in the salivary glands Anechoic Isoechoic or enlarged Hypoechoic Hyperechoic Sarcoidosis Oncocytoma Mucoepidemoid carcinoma Adenoid cystic carcinoma Metastases, malignant lymphoma

Abnormal Findings Anechoic Changes • Cysts: • Clinical features: salivary duct cysts, dysontogenetic duct anomalies, secondary cysts

• Causes: inflammation, trauma, sialectasia • Sonographic features: - Cystic lesion with smooth or irregular margins - Cysts always develop at the anterior border of the stemocleidomastoid muscle

Abscess • Ill-defined margins • Internal echo pattern ranges from anechoic to complex • Local tenderness

Isoechoic Changes and Enlargement • Viral sialadenitis: e.g., mumps • Enlargement of the parotid gland • Normal internal echo pattern

a, b Epidemic parotitis, a B-mode image: enlargement of the gland a, b Epidemic parotitis, a B-mode image: enlargement of the gland. b CDS: inflammatory hypervascularity

a, b Inflammation of the submandibular gland: hypoechoic swelling with anechoic streaks (edema)

- Chronic sialadenitis: • Recurrent swelling of the gland

Essentially normal echo pattern • Sialadenosis: "Hamster cheeks." nonneoplastic. Common in alcoholics, seen occasionally in diabetics (neurogenic?) • Painless enlargement of the parotid gland • Nonspecific internal echo pattern • May be slightly hyperechoic. Fine cysts may be seen

Immunogen sialadenitis • Slight enlargement; nonspecific structure • Facultative slight hyperechoic; fine cysts • Sarcoidosis: nonspecific echo pattern, may show decreased echogenicity

Sialadenosis. Longitudinal scan shows significant thickening of the parotid gland (cursors)

Hypoechoic Changes • Acute (or chronic recurrent) bacterial sialadenitis ; occurs predominantly in elderly patients with a weakened immune system

• Enlargement • Nonhomogeneous hypoechoic pattern • Possible findings: liquid foci of abscessation, echogenic structures with acoustic shadows (sialoliths). Possible anechoic ductal dilatation

Acute bacterial parotitis associated with an infected neck cyst Acute bacterial parotitis associated with an infected neck cyst. Oblique scan shows nonhomogeneous hypoechoic swelling of the parotid gland (P)

Parotid mixed tumor (sialadenoma, most common parotid tumor; strong propensity for recurrence, may undergo malignant transformation

• Round oval • Hypoechoic (when large: heterogeneous, cystic/hyperechoic pattern) • Smooth margins

a, b a Parotid mixed tumor (TU) a, b a Parotid mixed tumor (TU). MAX = maxilla b Cystadenolymphoma (Whartin tumor, cursors). Diagnosed by FNAB

Pleomorphic adenoma may undergo malignant transformation Smooth margins Homogeneous

• Cystadenolymphoma (Whartin tumor, more common entity; like oncocytoma, is classified as a sialoma • Markedly hypoechoic, nonhomogeneous echo pattern Smooth margins • Small cysts, may contain fine septations

• Uniformly hypoechoic • Smooth margins Oncocytoma • rare • Uniformly hypoechoic • Smooth margins

• Mucoepidermoid carcinoma: low-grade malignancy, the most common malignant tumor in adults (approximately 50% of malignant salivary gland tumors) • Very hypoechoic • Smooth margins • May contain cystic areas

• Adenoid cystic carcinoma (older term: cylindroma): high-grade malignancy marked by early infiltration of the facial nerve • Usually hypoechoic. Some lesions are heterogeneous or anechoic Ill-defined margins

• Metastases, malignant lymphoma: • Hypoechoic round or scalloped mass

Lymph node metastases (LN) from bronchial carcinoma: very hypoechoic mass in the parotid gland (P). MAN = mandibular echo with acoustic shadow

Hyperechoic Changes Sialadenosis: Frequently hyperechoic (due to diffuse fatty infiltration) Bilateral symmetry Painless enlargement

Lipoma, hemangioma, lymphangioma: Hyperechoic Lipoma with a feathery pattern; lymphangioma may have a cystic appearance

Sialolithiasis (salivary stone Sialolithiasis (salivary stone. presents clinically with swelling and acute pain Round or oval hyperechoic mass with an acoustic shadow, projected over the duct

Duct obstruction; anechoic duct structure at least 1 mm wide Rarely intraglandular, usually extraglandular with anteromedial extension into the buccal mucosa

a, b Sialolithiasis. a Abnormal anechoic duct structure, b Magnified view with the scan plane positioned for greatest clarity: microliths (arrow) with a distal acoustic shadow (S)

Evaluation and Further Testing Sonography: Diffuse and circumscribed salivary gland lesions can be clearly visualized with a high-resolution transducer. Most lesions (benign tumors) occur in the parotid gland.

Isoechoic diffuse swelling: usually viral parotitis Hypoechoic swelling: usually bacterial sialadenitis Circumscribed hypoechoic tumors: Ultrasound is of limited value for Benign malignant differentiation

Further testing Circumscribed hypoechoic masses: fine-needle aspiration cytology and histology Adenoid cystic carcinoma and carcinomas in adenomas: These malignancies often present clinically with rapid growth and facial nerve palsy.

Critical: FNAB, surgical diagnosis Infiltrative growth is clearly demonstrated by CT. MRI cannot differentiate between benign and malignant lesions (but is useful in the diagnosis of pleomorphic adenoma).

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