Submandibular, sublingual and minor salivary glands: anatomy and spectrum of

pathologiesValeria Romeo, M.D, Ph.D.

Department of Advanced Biomedical SciencesUniversity of Naples Federico II, Italy

valeria.romeo@unina.it

SUMMARY

ANATOMY

IMAGING TECHNIQUES

INFECTIOUS AND INFLAMMATORY PROCESSES

NEOPLASMS

ANATOMY

• SUBLINGUAL GLAND: SUBLINGUAL SPACE• SUBMANDIBULAR GLAND: SUBMANDIBULAR SPACE• MINOR SALIVARY GLANDS (MSG)..ANYWHERE ALONG THE AERODIGESTIVE TRACT!

ANATOMYMSG

Majority: Oral cavity

Other sites: respiratory tract, maxillary sinus, external auditory canal

Hiyama et al. Radiographics 2021

ANATOMYMinor salivary glands around the oral cavity

LabialAnterior/posterior (Ebner and Weber) lingualRetromolar palatine

800 – 1000 dispersed throughoutthe submucosa from the sinonasalcavity to the lung

ANATOMYSUBLINGUAL GLAND: SUBLINGUAL SPACESUBMANDIBULAR GLAND: SUBMANDIBULAR SPACE

KEY STRUCTURE: MYLOHYOID MUSCLE

Deep lobeSuperficial lobe

ANATOMYSUBLINGUAL GLAND: SUBLINGUAL SPACESUBMANDIBULAR GLAND: SUBMANDIBULAR SPACE

OTHER IMPORTANT STRUCTURES• GENIOGLOSSUS MUSCLE• HYOGLOSSUS MUSCLE

ANATOMY

ANATOMYSUBLINGUAL SPACESublingual glandSubmandibular gland (deep portion)Submandibular ductLingual artery/veinLingual brach mandibular division trigeminal nerve

SUBMANDIBULAR SPACESubmandibular gland (superficial portion)Level Ib lymph-nodesFacial artery/veinBranches hypoglossal nerve

AANATOMY

Sublingual gland

Mylohyoid muscle

Hyoglossus muscle

Submandibular glandSubmandibular gland

Genioglossus m

ANATOMYANATOMY ANATOMYANATOMY Genioglossus muscle

ANATOMY

WHARTON duct

Leaves the deep lobe, courses anteriorly and superiorlyto the floor of the mouth

ANATOMY - US

ABDM

SLG SLG

ABDMMYLOHYOID MUSCLE

MYLOHYOID MUSCLE

SMG

IMAGING TECHNIQUES

SIALOGRAPHY: sialoliths, chronic sialadenitisUltrasound: first level, guidance of biopsy/aspirationCT: lesions with calcifications, abscessesMRI: best performing modality

Internal tumor features (DWI)Tumor marginsPerineural spread

DIAGNOSTIC WORKUP ENLARGEMENT

Unilateral

Acute

Acutesialadenitis

Chronic

Chronic/focalsialadenitisNeoplasms

Bilateral

Chronic

SjogrenHIV or RT inducedsialadenitisIgG4

US AS FIRST LEVEL IMAGING MODALITY

INFECTIOUS AND INFLAMMATORY PROCESSES

1. SIALOLITHIASIS2. SIALADENITIS

SIALOLITHIASIS

Most common benign disease of salivaryglandsStagnation of salivaRisk factors: dehydration, smoking, drugsMost affected gland: submandibularTypical symptoms: pain and swelling

exacerbated while eating

SIALOLITHIASIS

ROLE OF IMAGING: detection of calculi

US: First-level, calculi of at least 1.3-3 mmDuct dilation, associated sialadenitis

CT: good sensitivity, also for assessment of inflammation and complications OBSTRUCTIVE SIALADENITIS

Ugga et al. Acta Otorhinolaryngologica Italica 2017

SIALOLITHIASIS

MRI SIALOGRAPHYSingle shot fast spin echo heavily T2-w sequence (same concept as MR cholangiopancreatography)Non invasive global assessment of of salivary gland ductal system

SIALOLITHIASIS – MR Sialography

Stone in the right submandibular glandmain distal of the duct

Karaca N. et al. Biomed Res Int. 2013

SIALOLITHIASIS MR Sialography

Assessment of changes related to chronic inflammation

Dilatations and strictures: chronic sialadenitis

Karaca N. et al. Biomed Res Int. 2013

LIMITATIONS

• CT: radiation exposure• MRI: costs, accessibility, long acquisition time

NNEW FRONTIER…Cone BBeam CT SIALOGRAPHY

• Iodinated contrast agent injection in the distal portion of the main duct• Reduced radiation exposure compared to CT

INFECTIOUS AND INFLAMMATORY PROCESSES

1. SIALOLITHIASIS2. SIALADENITIS

SIALADENITISINFECTIOUS

Viral, bacterial (S. Aureus)

Fat strandingThickening cervical fascia

and platysmaAbscesses

INFLAMMATORYMikulicz, Sjogren,

Sarcoidosis, Chronicsclerosing sialadenitis, IgG4

(Kuttner)

CystsMild fatty replacement

LN aggregates

POST-RADIATIONOropharyngeal cancer

treatment

Hyperenhancement(>45Gy)

Acute phase: enlargement

Chronic phase: volume reductionVolume reduction

Large fatty replacementCalcifications

Ductal stenosis + dilation

AtrophyFibrosis (low to intermediate MRI signal)

COMPLICATED OBSTRUCTIVESIALADENITIS

Ugga et al. Acta Otorhinolaryngologica Italica 2017

NEOPLASMS

INTRODUCTION

Entities of salivary glands tumors accordingto the upfdated WHO classification (2017)

SIMPLIFY EPIDEMIOLOGY AND KEY IMAGING FINDINGS

43

GENERAL CONCEPTS - MSG

An accurate diagnosis based on imaging is challenging, even for the pathologist

BENIGN/MALIGNANTTUMOR EXTENT ASSESSMENT

GENERAL CONCEPTSBENIGN LESIONS MALIGNANT LESIONS

SMALL (< 2 CM)Minimal/homogeneus enhancement

LARGE (>2 cm)Heterogeneous enhancement

Well circumscribed LOW GRADEDifferent degrees of enhancement

HIGH GRADEInfiltrative marginsNodal metastasisPerineural spread

INCIDENCE

BENIGN MALIGNANT

80-90%20-10%

50% 50% SUBMANDIBULAR

SUBLINGUAL/MSG

PAROTID80% 20%

FREQUENTLY ENCOUNTERED TUMOR TYPES

BENIGN MALIGNANT

Pleomorphic adenoma Adenoid cystic carcinomaMucoepidermoid carcinoma

SUBMANDIBULAR

SUBLINGUAL/MSGAdenoid cystic carcinomaMucoepidermoid carcinoma

GGENERAL CONCEPTS

PLEOMORPHIC ADENOMA

Glandular epithelium and myoepithelialcomponentsParotid, submandibular, MSG

Well circumscribed multilobulated mass with dark T2 rim (tumor capsule)

High T2 and ADC signalHeterogeneous nodular enhancement

PLEOMORPHIC ADENOMA

Kakimoto N et al. EJR 2009

PLEOMORPHIC ADENOMA

Kakimoto N et al. EJR 2009

PLEOMORPHIC ADENOMA

Abdel Razek & Mukherji et al. Neuroimag Clin N Am (2018)

MUCOEPIDERMOID CARCINOMA

Most common tumor type in MSG (50%)Low, intermediate and high-grade subtypes

TYPICAL IMAGING FEATURES

LOW GRADESmooth marginsMucin-containing cystic content

HIGH GRADEPoorly defined marginsSolid (hypointense on T2w)Adjacent structures invasion

MUCOEPIDERMOID CARCINOMA

Hiyama et al. Radiographics 2021

ADENOID CYSTIC CARCINOMA

Different pathological subtypes: tubular(grade I), cribriform (grade I), solid (< 30% grade II, >30% grade III)Involving mainly parotid and MSG

T2w signal depending on high (hypointense) or low (hyperintense) cellularity

Perineural spreadDestructive pattern with invasion bone and

surrounding structuresCervical nodal metastasis

ADENOID CYSTIC CARCINOMA

Abdel Razek & Mukherji

ADENOID CYSTIC CARCINOMA

Hiyama et al. Radiographics 2021

RANULAMucous retention, frequent in the sublingual gland

Simple ranula

Mylohyoid muscle

Deep ranulaLeakage from a sublingual ductInfiltration of the submandibular space or contralateral floor of the mouth

RRANULA

Ugga et al. Acta Otorhinolaryngologica Italica 2017

TAKE HOME POINTS

INFLAMMATORY DISEASE• US first level imaging modality• CT and MRI for complication assessment

NEOPLASMS• US as first approach• MRI for tumor characterization and staging• Differentiation benign/malignant• Tumor spread for treatment planning