Definition/General
Introduction:
Normal salivary gland FNAC represents the baseline cytological appearance of healthy salivary gland tissue
It shows characteristic mixed cellular components including acinar cells, ductal cells, and myoepithelial cells
Understanding normal cytology is essential for identifying pathological changes
It serves as the foundation for differential diagnosis in salivary gland cytopathology.
Origin:
Derived from the three major salivary glands (parotid, submandibular, sublingual) and numerous minor salivary glands
The cytological sample represents the functional parenchyma of the gland
Normal architecture consists of acinar units connected by ductal systems
The cellular composition varies slightly between different glandular sites.
Classification:
Classified as normal cytology according to the Milan System for reporting salivary gland cytopathology
Falls under Category I: Non-diagnostic/Inadequate if cellular content insufficient
Category II: Non-neoplastic when adequately cellular with normal morphology
Requires adequate cellular representation from all components.
Epidemiology:
Normal FNAC findings represent the majority of negative salivary gland aspirates
Accounts for 60-70% of all salivary gland FNACs in screening populations
Higher prevalence in younger age groups without clinical symptoms
Indian population shows similar cytological patterns to global standards
Age-related changes may be seen in elderly patients.
Clinical Features
Presentation:
Usually performed for clinically palpable but non-specific masses
May be part of routine screening in high-risk patients
Often done to rule out malignancy in suspicious lesions
Can be performed for bilateral gland enlargement evaluation
Sometimes done for dry mouth symptoms (sicca syndrome investigation).
Symptoms:
Typically asymptomatic patients with normal gland function
No pain or functional impairment
Normal salivary flow and composition
Absence of inflammatory symptoms
No history of recurrent infections or autoimmune disease.
Risk Factors:
Age-related changes in cellular composition
Smoking history may affect cellular morphology
Radiation exposure can cause cellular atypia
Autoimmune conditions may show early changes
Medication effects on glandular function.
Screening:
FNAC indicated for palpable masses >1 cm
Ultrasound-guided sampling for deep-seated lesions
Clinical correlation with imaging findings
Patient history review for risk factors
Physical examination of all salivary glands.
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Gross Description
Appearance:
Aspirate typically yields clear to slightly turbid fluid
Volume usually 0.5-2 ml per aspiration attempt
May contain small tissue fragments
Color ranges from clear to pale yellow
Viscosity varies with mucin content.
Characteristics:
Fluid consistency is thin to slightly viscous
May contain scattered tissue particles
Clear appearance without blood contamination
Mucoid quality reflects normal secretions
Absence of purulent material or debris.
Size Location:
Sample volume depends on gland size and accessibility
Parotid glands yield larger volumes
Submandibular samples may be more mucoid
Minor glands provide smaller specimens
Multiple passes may be needed for adequate cellularity.
Multifocality:
Bilateral sampling may show similar morphology
Minor variations between different glandular sites
Age-related changes may be uniformly distributed
No focal abnormalities or heterogeneous areas
Consistent appearance across multiple aspirations.
Microscopic Description
Histological Features:
Mixed population of acinar cells, ductal cells, and myoepithelial cells
Acinar cells show abundant granular cytoplasm
Ductal cells display moderate amounts of pale cytoplasm
Background contains proteinaceous material
Inflammatory cells are sparse or absent.
Cellular Characteristics:
Acinar cells: polygonal shape with eccentric nuclei
Cytoplasm is finely granular and eosinophilic
Ductal cells: smaller and rounder with central nuclei
Myoepithelial cells: spindle-shaped with elongated nuclei
Nuclei show fine chromatin pattern and small nucleoli.
Architectural Patterns:
Cells arranged in loosely cohesive clusters
Acinar cells form grape-like arrangements
Ductal cells show honeycomb pattern
Single cells scattered throughout background material
Myoepithelial cells typically isolated or in pairs.
Grading Criteria:
Adequacy assessed by cellular density and representation
Minimum requirement: 5-6 clusters of epithelial cells per slide
Nuclear morphology: uniform and bland
Chromatin pattern: fine and evenly distributed
Nucleoli: inconspicuous or small
Mitotic activity: absent or rare.
Immunohistochemistry
Positive Markers:
Acinar cells: Amylase positive
Alpha-amylase
Lysozyme
Ductal cells: CK7 positive
CK8/18
EMA positive
Myoepithelial cells: p63 positive
Smooth muscle actin
Calponin positive.
Negative Markers:
S-100 protein (except myoepithelial cells)
Vimentin negative in epithelial components
CEA typically negative or weak
Chromogranin negative
Synaptophysin negative
Ki-67 index very low (<5%).
Diagnostic Utility:
IHC rarely needed for normal cytology
May be used to confirm cellular components
Helpful in distinguishing from reactive changes
Can identify myoepithelial cells when morphologically unclear
Useful for educational purposes and cell type identification.
Molecular Subtypes:
Normal salivary glands show physiological expression patterns
No specific molecular markers required for diagnosis
Gene expression profiles reflect functional specialization
Secretory proteins appropriately expressed
Growth factors at baseline levels.
Molecular/Genetic
Genetic Mutations:
Normal salivary glands show wild-type gene expression
No pathogenic mutations detected
Age-related changes in gene expression possible
Cellular senescence markers may be present in elderly patients
No oncogenic alterations identified.
Molecular Markers:
Normal expression of housekeeping genes
Appropriate levels of secretory proteins
Cell cycle regulators at baseline levels
No overexpression of growth factors
Normal DNA repair mechanisms active.
Prognostic Significance:
Normal cytology indicates absence of malignancy
Good correlation with clinical findings
Low risk of sampling error in adequate specimens
Excellent prognosis with normal function
No follow-up required unless clinical changes occur.
Therapeutic Targets:
No therapeutic intervention required
Maintenance of normal glandular function
Prevention strategies for risk factor modification
Regular follow-up for high-risk patients
Patient education about warning signs.
Differential Diagnosis
Similar Entities:
Reactive changes due to chronic sialadenitis
Age-related atrophy with reduced cellularity
Post-radiation changes with cellular atypia
Sjogren syndrome with lymphoid infiltrate
Drug-induced changes affecting cellular morphology.
Distinguishing Features:
Normal: Bland nuclear morphology
Normal: Mixed cell population preserved
Normal: Absent inflammatory background
Sialadenitis: Inflammatory cells present
Sialadenitis: Reactive epithelial changes
Atrophy: Reduced cellular density
Atrophy: Predominantly ductal cells
Sjogren: Lymphoepithelial lesions.
Diagnostic Challenges:
Age-related changes may mimic pathological processes
Sparse cellularity can be misinterpreted as inadequate
Technical artifacts from preparation methods
Sampling from different glandular regions
Distinction from early inflammatory changes.
Rare Variants:
Oncocytic metaplasia in aging population
Squamous metaplasia from chronic irritation
Mucous cell hyperplasia in minor glands
Lipomatous replacement with age
Sclerosing changes in elderly patients.
Sample Pathology Report
Template Format
Sample Pathology Report
Complete Report: This is an example of how the final pathology report should be structured for this condition.
Specimen Information
Fine needle aspiration from [location] salivary gland
Specimen Adequacy
Adequate for evaluation - contains representative epithelial cells
Cellular Composition
Mixed population of acinar cells, ductal cells, and scattered myoepithelial cells
Morphological Features
Cells show bland nuclear morphology with fine chromatin and inconspicuous nucleoli
Background
Clean background with proteinaceous material, minimal inflammatory cells
Milan System Category
Category II - Non-neoplastic
Cytological Diagnosis
Normal salivary gland cytology
Recommendation
Clinical correlation recommended. No further cytological follow-up required unless clinically indicated