PATHOLOGY OF SALIVARY GLANDS
-salivary glands can be classified according to prevailing type of secretory cells
-serous glands, mucous glands and mixed seromucous
-salivary gland tissue consists of- acinar cells of serous and mucous typemyoepithelial cells- epithelial cells of salivary ducts, mesenchymal cells of the
connective tissue (adipose and fibrous, nerves, blood vessels), and inflammatory
cells
according to the anatomic location- salivary glands include paired major glands
(parotid, submandibular, sublingual) and minor glands of upper aerodigestive
tract
-1.- major glands include parotid- the largest gland, enclosed by capsule,
located anterior to the ear, composed of serous acini, secretory ducts
-about 20 lymph nodes located in each parotid gland
-submandibular-located in the submandibular triangle, seromucous gland
-subligual gland, the smallest of major glands, in the floor of mouth, prevailing
mucous acini,
-2.- minor glands of the oral mucosa
-minor glands have mixed serous and mucous acini in varying proportions
cellular components:
-of particular interest- myoepithelial cells (MEC) - believed to have
contractile properties that assist in secretion of saliva
-microscopical examination shows that MECs are thin and spindle-shaped cells
around acini and intercalated ducts situated between basement membrane and
epithelial ductal cells
-they display features of both smooth muscle cells and epithelium
DISORDERS OF SECRETION
Xerostomie- dry mouth-decrease in the secretion of the saliva, it is a symptom
and not a disease
-xerostomia is important-accompanied by infection, ulceration and rapid
dental caries, in addition- there is difficulty in eating, speaking and swallowing
-conditions that may lead to xerostomia-
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-flow rate of saliva may be normal-there is only a feeling of dry mouthbecause of local factors, smoking, mouth breathing, etc
-in other cases-real decrease of flow associated with stress, fear as a
effect of increased sympathetic activity
-common side effect of many drugs, such as sedatives, antihypertensives, and
anti-emetics, antihistamines, etc-normal capacity of glands
-functional capacity of salivary glands may be reduced due to a loss of
secreting cells- irradiation sialadenitis- salivary glands were damaged by
therapeutic radiotherapy of head and neck region because of cancer
-autoimmune sialadenitis in Sjogren syndrome- permanent and
severe xerostomia
-other disorders, such as dehydratation, uremia, diabetes mellitus,
hypovolemic shock
Sialorrhoe (Ptyalism)- true increase in salivary flow is rare
-may be present in mercury poisoning, rabies, in some neurological
disturbances, epilepsy
OBSTRUCTIVE AND INFLAMMATORY DISORDERS
These include mucus escape reactions, which are not lined by epithelium,
(extravasation mucocoele, ranula), mucus retention cyst (true cyst lined by
epithelium), sialolithiasis and a variety of other conditions (e.g. tumours) that
can cause obstruction
Common to all causes are the effects of obstruction, which are acinar
atrophy, stasis, secondary infections, epithelial damage and scarring, and these
can aggravate the obstruction.
-they occur as a result of stasis of saliva, acute and chronic inflammation and
sialolithiasis
-sialolithiasis
-sialoliths are calcified masses (calculi, stones)- that develop in ductal system of
salivary glands
- they occur mainly in the large ducts of submandibular gland - (due to thicker
mucous secretion than in parotid)
-obstruction of salivary duct by stones
-chronic sclerosing sialadenitis (Kuttner tumor) - is chronic inflammatory
disorder, in most cases secondary to calculi, it can occur at any age, though the
mean is about 45 yr, considerably more common than acute sialadenitis
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- it is most often seen in submandibular gland, patients present with pain and/or
sweeling of the gland associated with eating
-grossly it is characterized by enlargment and firm consistency of the gland- in
the end-stages of the disease there is little remaining glandular tissue- gland is
totaly replaced by fibrous tissue - mimic tumor (Kuttner tumor)
microscopically: chronic sialadenitis is characterized by fibrosis, progressive
atrophy of salivary gland acini and abundant mixed inflammatory infiltrationgerminal centres, some neutrophils, ductal epithelium may show hyperplasia and
metaplasma
Mucus Escape Reaction.
This is defined as pooling of mucus in a cavity in the connective tissue not
lined by epithelium- called „extravasation mucocele“.
The sites are (minor) lower lip 65%, palate 4%, buccal mucosa 10%, and
(major) parotid 0.6%, submandibular 1.2% and sublingual (ranula) 1.1%.
-most patients are young
- pathogenesis is traumatic damage of a duct, leading to mucus pooling. In the
lip, it presents as a raised swelling, which is sometimes blue. The sublingual
ranula presents as a swelling of the floor of the mouth.
Microscopy shows a well-defined mucin-filled cavity without epithelial lining.
There is a mixed inflammatory infiltrate, including foamy histiocytes, and later
proliferation of granulation tissue
- salivary gland tissue shows chronic sialadenitis, acinar atrophy and
fibrosis. The outcome is that recurrences are frequent, especially in
sublingual ranula.
OTHER INFLAMMATORY DISORDERS
1.- Benign lymphoepithelial lesion and Sjogren syndrome
-Sjogren syndrome -is an autoimmune inflammatory exocrinopathy with
multisytem manifestations-characterized by lymphocytic infiltration of exocrine
glands, particularly the lacrimal and salivary glands resulting in reduced
secretion
-immunologically, the disease is characterized by B-cell hyperactivity and
the production of many circulating auto-antibodies
-in over half of cases Sjogren syndrome is accompanied by another autoimmune disorder, such as rheumatoid arthritis, systemic lupus erythematodes,
systemic sclerosis, polymyositis, primary biliary cirhosis
clinically:
glands
Sjogren syndrome is characterized by swelling of major salivary
-dry eyes- keratoconjunctivitis sicca
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-dry mouth- xerostomia
-rheumatoid arthritis or/and another autoimmune disorder
histologically:
-the affected lacrimal and salivary glands are diffuselly infiltrated by
lymphocytes and plasmacytic cells, there is an atrophy of acinar salivary gland
epithelium, accompanied by proliferation of epithelial and myoepithelial cellepi-myoepithelial islands and with fibrosis - called benign lymphoepithelial lesion
or lymphoepithelial sialadenitis (LESA)
-higher risk of development of malignant lymphoma of MALT type - in salivary
gland affected by S. syndrome
-miscellaneous inflammatory disorders- there is a variety of noninfectious inflammatory conditions in salivary glands, such as
-sarcoidosis -chronic granulomatous inflammatory lesion characterized by
epithelioid granulomas with giant cells of Langhans type
-Kimura disease (epithelioid hemangioma, angiomatoid lymphoid hyperplasia
with eosinophilia)- distinctive lesion particularly affecting soft tissues of head
and neck area, characterized by ….
SALIVARY GLAND INFECTIONS
-mumps virus infection- mumps is an acute infectious disease caused by
a paramyxovirus which has predilection for parotid gland
-the gland is enlarged, swollen, painful, in most cases bilateral, accompanied with
fever and headache
-mumps is a self-limited disease, occurs most often in children in school age,
there is typically incubation period of 2-3 weeks,
-less frequently, other organ may be involved, such as pancreas, testes
-cytomegalovirus infection- CMV is a ubiquitous herpes virus detectable
in more than 80% of adults
-infections may follow debilitating diseases, such as malignant neoplasms,
immunosupression, acquired immunodeficiencies, bone marrow transplantations,
etc
-acute bacterial parotitis- rare, occurs usually in debilitated patients
with poor oral hygiene -acute suppurative infiltration, usually with abscess
formation
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-grossly dilated ducts filled with pus cells (neutrophils) and diffuse interstitial
acute leukocytic infiltration between acinar cells
-focal aggregations of neutrophils may form abscesses- this can only heal by
fibrosis- distortion of gland architecture which predispose to further infections
NON-NEOPLASTIC NON-INFLAMMATORY LESIONS
1.-Necrotizing sialometaplasia- is a benign self-healing lesion affecting
especially the minor salivary glands of the palate
-it presents as mucosal ulcer which usually heals spontaneously if left
alone, the major problem is that NS clinically and histologically can simulate
squamous cell carcinoma
-some cases follow surgery or even minor trauma such as from an illfitting denture, the underlying process is considered to be ischemic, the cause is
however unknown
histology: shows lobular coagulative necrosis of acini, squamous metaplasia of
ducts, a chronic inflammatory infiltration and pseudoepitheliomatous hyperplasia
of the surface
2.- Sialadenosis- is a non-inflammatory process of the salivary glands due
to metabolic and secretory disorders accompanied by painless swelling of the
parotid glands
-it is related to endocrine dysfunction (thyroid and ovarian insufficiencies) and
nerve dysfunction
-it is also seen in malnutrition, chronic alcoholism, liver cirrhosis, may be linked
to drugs, etc.
3.- Adenomatoid hyperplasia of mucous salivary glands- the lesion is
asymptomatic, found accidentally on routine dental examination
-grossly- nodular lesion on the palate mimicking benign tumor
-most patients –adult, 3-5th decades, etiology is unknown
4.- irradiation changes- salivary glands are very senstitive to irradiation,
a xerostomia is a common complication
-acute radiation injury-swelling of the gland- necrosis of acinar cells,
acute inflammatory response
-chronic injury- characterized by fibrosis, loss of acini, and squamous
metaplasia
-when all glands are involved, loss of saliva is irreversible
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5.- oncocytic lesions- oncocytic change of salivary glands is relatively
common particularly in elderly, it is characterized by cells with abundant
granular eosinophilic cytoplasm due to increased number of mitochondria
-it is a non-neoplastic metaplastic change, spectrum of lesions
-focal and diffuse oncocytic metaplasia
-ductal oncocytosis
-multifocal oncocytic hyperplasia
exact cause is speculative
SALIVARY GLAND CYSTS
-non-neoplastic cysts and pseudocysts account for about 10% of salivary
gland lesions
-they can be classified as congenital (dysgenetic) – salivary polycystic
dysgenetic disease
acquired- true cystic lesions with epithelial lining- salivary duct cyst,
lymphoepithelial cyst
pseudocysts- without epithelial lining- mucus escape reaction, ranula
cystic neoplasms should be distinguished- LG mucoepidermoid carcinoma,
Warthin tumor, cystadenoma, etc.
mucus escape reaction- is defined as a pooling of mucus in a cavity
within the connective tissue that is not lined by epithelium
-results from traumatic rupture of a salivary duct of major or minor gland
clinically appears as:
mucocele- most commonly lesions of lips -more often lower lips
ranula- is a type of mucus escape reaction that occurs in the floor of
mouth- bluish in color
histologic features:
-early lesion consists of well-defined cavity in the soft tissue of the oral
mucosa - filled with mucinous material with admixture of inflammatory
cells and foamy macrophages
later, granulation tissue grows
organization of the mucocele
progressively
into
the
cavity-
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mucus retention cyst -is a true cyst, less common than mucus escape reaction
-clinical presentation is that of slowly growing painless, circumscribed
lesion of variable size and location- more often in parotid and
submandibular glands
salivary duct cyst (sialocyst)- represents true cysts with epithelial lining, it
develops as a consequence of duct obstruction. The lesions are unilocular, but
rarely they may be multicystic. The absence of lymphoid infiltrate allows to
distinguish salivary duct cyst from Warthin tumor, lymphoepithelial cyst and
branchial cleft cyst.
Cystic lymphoid hyperplasia in AIDS
Rarely patients with AIDS present with unilateral or bilateral
enlarging cystic masses in parotid glands.
These lesions have been reffered to as AIDS-related parotid gland cysts
or cystic lymphoid hyperplasia in AIDS (cystic benign lymphoepithelial
lesions)
-The cysts measure up to 4 cm in diameter and are lined by
squamous epithelium. The surrounding parotid gland tissue is replaced by
hyperplastic lymphoid tissue with irregular enlarged follicles.
-The distinction between AIDS-related parotid gland cysts and
benign lymphoepithelial lesion (BLEL) may be difficult, bue well developed
cases related to AIDS are characterized by a presence of large
irregularly branching cysts with prominent follicular hyperplasia.
Benign lymphoepithelial cyst- well circumscribed and predominantly unilocular
-Histologically the cyst is lined by stratified squamous epithelium,
although mucin producing cells may be also present.
-The cyst wall reveals a dense lymphoid tissue with prominent germinal
centres of follicles.
Salivary Polycystic Dysgenetic Disease.
This very rare condition resembles cystic anomalies of other organs, such
as the kidney, liver and pancreas, although no association has been described.
-Some cases are familial, and almost all cases occurred in females. Most
- It only affects the parotid glands, usually bilaterally.
Microscopically, the glands maintain their lobular architecture, the cysts vary in
size up to a few mm, and they are irregular in shape and often interconnect. The
lining epithelium is flat, cuboidal to low columnar, sometimes with an apocrine
like appearance.
The lumen contains secretion with spherical microliths.
Remnants of salivary acini are seen between the cysts, and thick fibrous
interlobular septa are often prominent. Inflammation is at most mild
Sclerosing polycystic adenosis
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-rare benign pseudoneoplastic condition of major salivary glands similar to
fibrocystic disease of the breast
-It affects mainly females, adult
-grossly- slow-growing masses in the parotid gland, gland is largely replaced by
multiple discrete firm, rubbery nodules.
-microscopic examination- well-circumscribed, unencapsulated lesion
composed of a lobular arrangement of proliferating ducts and acini with
cystic ducts containing viscous secretion
There is often intraluminal epithelial proliferation, the lining comprises a
spectrum of apocrine, mucous, squamous cells and balooned sebaceous-like cells,
although true goblet cells are not seen. There is sometimes nuclear
pleomorphism, even occasionally suggesting dysplasia
-bening neoplasm, the lesion is monoclonal
Clinical features- in 1/3 cases recurrences, benign lesion
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