Introduction to Pathology of Oral Soft Tissues Flashcards
The two parallel/pedagogic methodologies for categorizing abnormalities of the oral mucosa…
- Etiologic Approach
- Clinical Features
Etiologic approach…
Abnormalities of the oral mucosa are presented in a sequence based on their cause, irrespective of their clinical presentation.
Etiologic categories
- Developmental
- Autoimmune
- Metabolic
- Neoplastic
- Infectious
- Traumatic
Clinical features approach
Categorizes disease based on clinical features rather than their etiology
Differential diagnosis method
Groups diseases sharing a similar clinical presentation
Most lesions of the oral mucosa fall into one (or more) of the following categories:
- Flat lesions
- Raised lesions (enlargements)
Flat lesions may present as…
- Solitary ulcers
- Multiple ulcers
- White plaques and patches
- Red macules and patches
- Red and white patches or plaques
- Pigmented merciless and patches
Raised lesions (enlargements) may present as…
- Normal-colored well-defined nodules
- Discolored well-defined nodules
- Verrucous (warty) enlargements
- Cratered or ulcerated enlargements
- Multiple enlargements
- Generalized gingival enlargements
Criteria used to classify lesions of the oral mucosa…
include the number of lesions (single or multiple), color, and shape –> these correlate with histologic changes
In general, what does oral mucosa consist of?
- Surface layer of stratified squamous epithelium
- Underlying layer of connective tissue
- This basic architecture is modified to correspond with function in different areas of the mouth.
Regions of the oral mucosa that are keratinized
- Masticatory gingivae
- Palatal raphe
- Anterior hard palate
- Posterior hard palate
- Anterior dorsal tongue
- Vermilion
Regions of the oral mucosa that are non-keratinized
- Sulcular gingivae
- Posterior dorsal tongue
- Ventral tongue
- Soft palate
- Buccal mucosa
- Labial mucosa
- Floor of mouth
- Alveolar mucosa
Regions of the oral mucosa with attached submucosa
- Anterior hard palate
- Posterior hard palate
- Posterior dorsal tongue
- Ventral tongue (+/-)
- Soft palate
- Buccal mucosa
- Labial mucosa
- Vermilion
Regions of the oral mucosa with loose submucosa
- Floor of mouth
- Alveolar mucosa
Regions of the oral mucosa with no-submucosa – firmly attached
- Masticatory gingivae
- Sulcular gingivae
- Palatal raphe
- Anterior dorsal tongue
(Keratinized) Stratified squamous epithelium can be…
- ortho-keratinized
- parakeratinized
What is orthokeratinized?
When the stratum corner is an amorphous layer of keratin without nuclei
What is parakeratinized?
Pyknotic nuclei are retained in the epithelium
Where is the epithelium keratinized or parakeratinized?
In the masticatory mucosa of the hard palate and gingivae, and in the specialized mucosa of the dorsal surface of the tongue.
Note: these areas are particularly subject to friction.
This is usually prominent in keratinized areas…
Rete ridges
Lining mucosa
- Subject to less friction
* The stratified squamous epithelium usually lacks both keratin and prominent rete ridges.
Predominant cell type in stratified squamous epithelium.
keratinocytes (in stratum spinosum)
Shape of keratinocytes
polygonal
What joins keratinocytes?
These polygonal cells are joined to one another by desmosomes which look like intercellular bridges under light microscope.
Purpose of desmosomes?
joins keratinocytes
Desmosomes contain specific proteins, what are they?
desmoglein 1 and 3, two of several proteins in the desmosomal cadherin family
What produces keratin?
keratinocytes
Cell types found in oral stratified squamous epithelium
- keratinocytes
- melanocytes
- Langerhans cells
- Merkel cells
Location of melanocytes
Stratum basale (basal layer)
What do melanocytes do?
Inject melanosomes (melanin) into adjacent keratinocytes
Characteristics of melanocytes
- found in basal layer
- no intercellular bridges
- dendritic
- inject melanin into keratinocytes
What are merkel cells?
sensory mechanoreceptors
What do merkel cells contain?
small dense neurosecretory granules
Characteristic of base of Merkel cell?
Base of cell associated with free nerve endings with an expanded terminal disc
What are Langerhans cells?
Dendritic, antigen-presenting cells
What do Langerhans cells do?
They trap antigens entering epithelium and present them to T lymphocytes.
Characteristic shape of Langerhans cells
Tennis racket or rod-shaped Birbeck granules
What are Birbeck granules?
- Small vesicles with bulbous extensions on their end.
* Associated with Langerhans cells.
Where do you find hemidesmosomes?
At regular intervals on the cytoplasmic side of the keratinocyte basal cell membrane.
What do hemidesmosomes do?
Anchor keratinocytes to the basement membrane.
What do hemidesmosomal plaque contain?
plectin, desmoplakin and BPAG-1 (all of which bind to keratin filaments) and transmembrane proteins (BPAG-2 and integrin α6β4) that link plaque to basal lamina
What is the basement membrane?
An acellular layer between the epithelium and the underlying connective tissue.
Is the basement membrane visible with light microscope?
Yes, but its components are not.
What makes up the basement membrane?
- a basal lamina (produced by the epithelium)
* a reticular lamina (a product of the connective tissue)
Anchoring filaments
Threadlike structures that connect hemidesmosomes to the basal lamina
Layers of the basal lamina
- Lamina Lucida (adjacent to the epithilium)
* Lamina densa (deep to epithelium)
Basal lamina contains antigens important in….
vesiculobullous diseases
What does lamina lucida contain?
laminin, BPAG-2, integrins
What does lamina densa contain?
type IV collagen, heparan sulfate
Type of collagen in anchoring fibrils
type VII
Where does the anchoring fibrils connect?
lamina densa into the reticular lamina
What is epidermolysis bullosa?
a group of inherited diseases characterized by mucocutaneous vesicles and bullae
Defective cellular cohesion causes what?
Clefting at various levels, within or below the surface epithelium
Broad categories of epidermolysis bullosa
simplex, junctional, dystrophic, hemidesmosomal
Clefting occurs where in the simplex, junctional, dystrophic, and in the hemidesmosomal types of epidermolysis bullosa?
- simplex - within the epithelium
- junctional - at the level of the lamina lucida (affecting the α3, β3 and γ2 subunits of laminin)
- dystrophic types - below the lamina densa (involving type VII collagen)
- hemidesmosomal type - abnormalities associated with hemidesmosomal attachment proteins, such as plectin, BP180 (BPAG-2), and α6β4
What property of connective tissue has clinical significance?
its layers which vary in thickness
Layers of connective tissue: At sites where the connective tissue is wide, it is usual to refer to the layers as…
Superficial region is referred to as lamina propria, and the deeper region as submucosa.
Only site in the human oral mucosa where an anatomical border has been reported between the two layers of connective tissue
soft palate, where an elastic lamina has been described
Where is lamina propria found in the oral mucosa?
all sites
Where is submucosa found?
- beneath lining (non-keratinized) mucosa Except on the ventral surface of tongue (where there may be a small amount)
- beneath masticatory (keratinized) mucosa in lateral hard palate
Submucosa is loose in…
- Floor of mouth
* Alveolar mucosa including vestibular folds
Submucosa tightly binds mucosa to skeletal muscle in the…
- lips
- soft palate
- buccal mucosa
- posterior dorsal surface of the tongue
Masticatory (keratinized) mucosa is tightly bound to what?
Underlying tissue
How is masticatory mucosa bound to bone?
The mucosa is tightly bound to underlying bone without an intervening mucosa in the midline palatal raphe and gingivae; this is known as mucoperiosteum.
How is masticatory mucosa bound to skeletal muscle?
Tightly bound without a submucosa on the anterior dorsal surface of the tongue
Masticatory mucosa in the _______ regions of the _______ palate is tightly bound to bone by what?
Masticatory mucosa in the lateral regions of the hard palate is tightly bound to bone by COLLAGEN.
What is mucoperiosteum?
mucosa attached to bone without submucosa
Mucoperiosteum is found in what structures?
- Gingivae
* Midline palatal raphe
Vertical bands of collagen create what?
Compartments that are occupied by:
• anterior tissue in the anterior half of the hard palate
• minor salivary glands posteriorly
Where are minor salivary glands found?
In the lamina propria or submucosa of all regions of the oral cavity with the following exceptions: gingivae, anterior hard palate and palatal raphe, and dorsal surface of the anterior two thirds of the tongue.
Where are salivary gland neoplasms exceedingly uncommon?
Gingivae, anterior hard palate and palatal raphe, and dorsal surface of the anterior two thirds of the tongue.
Intraoral minor salivary glands are what?
Except for the serous glands of von Ebner, intraoral minor salivary glands are purely or mainly mucous.
Aggregations of lymphoid nodules covered by surface epithelium with an incomplete fibrous connective tissue capsule on their deep surface.
Tonsils
Crypts
Tonsils are penetrated by invaginations lined by extensions of the surface epithelium. When these infoldings are deep, they are known as crypts.
Location of palatine tonsils
Between the palatoglossal and palatopharyngeal folds
Location of lingual tonsils
dorsal surface of the posterior one third of the tongue
Where are foliate papillae found?
Vertical folds on the lateral surface of the tongue at the junction between the anterior two-thirds and posterior one third.
Foliate papillae usually contain what?
Lymphoid nodules
Where are ectopic lymphoid tissue (tonsils) found?
Sometimes seen as yellowish papules in the anterior floor of the mouth, soft palate or buccal mucosa.
What are fordyce granules?
Sebaceous glands within the oral mucosa
Present as multiple small (1 to 2 mm) yellowish macules or papules on the buccal mucosa, labial mucosa and other sites.
Fordyce granules
Mucosal disturbances in color, shape, and consistency are correlated with…
histologic change
Macule
Circumscribed discolored spot not raised above level of surrounding mucosa
Patch
Flat, discolored area exceeding 5 mm in diameter
Plaque
Slightly elevated mucosal enlargement with a flat surface
White lesions of the oral mucosa have a white appearance why?
Due to disturbances in the surface stratified squamous epithelium. These include:
• epithelial hyperkeratosis (ortho or para)
• epithelial hyperplasia
• vacuolization of epithelial cells
• epithelial necrosis (overlying an ulcer)
This may create a white appearance within the lamina propria…
dense collagenous fibrous connective tissue within the lamina propria
Fibrinous exudate over an ulcer appears how?
white or whitish-yellow
Causes of mucosal erythema (red lesions) include…
- erosion (loss of superficial epithelium) allowing vasculature to show
- epithelial atrophy or frank ulceration
- an actual increase in number of vessels (often seen in inflammation, granulation tissue and vascular tumors)
- extravasation of blood into tissues
Pigmented (black, blue, or brown) lesions/discolorations are due to…
- melanin (with or without an increased number of melanocytes)
- hemosiderin
- foreign material (such as amalgam)
- medications (due to stimulation of melanin deposition or deposition of drug metabolites)
Physiologic melanosis and melanotic macules
Increased melanin with little or no melanocyte proliferation
Increased number of melanocytes are observed in…
- lentigines
- nevomelanocytic nevi
- melanoacanthosis
- melanomas
What’s responsible for producing the yellow appearance observed in yellow lesions
Increased amounts of adipose tissue, sebaceous glands, amyloid, keratin (as in oral lymphoepithelial cysts) or a fibrinopurulent membrane over an ulcer
Represent the loss of continuity of the full-thickness of surface epithelium…
Ulcers
Exposure of underlying vascular connective tissue creates…
a red ulceration
Structure of ulcer bed
Often white or yellow due to a thin removable fibrinopurulent film or necrotic epithelium over the connective tissue
Cause of mucosal enlargements
Uneven proliferation of cells or an increased amount of semisolid material
Solid enlargements are usually due to…
- Proliferation of cells which are normally found at the site of the swelling.
- Occasionally, the proliferating cells are cell types not normally found in the oral mucosa.
Proliferating cells normally found at the site of the lesion include:
- neoplasms
- hamartomas
- reactive lesions
What are hamartomas?
Developmental anomalies involving abnormal arrangement of tissues normally occuring at a particular site
What is a reactive lesion?
A limited response to a challenge such as irritation.
Proliferating cells not normally found at the site of lesion include:
- metastases
- choristomas
- teratomas
What are choristomas?
Normal cells in an abnormal location
What are teratomas?
Cells representative of more than one germ-cell layer
Enlargements usually exhibit a smooth surface except…
- unless proliferation occurs within the surface stratified squamous epithelium
- the surface is ulcerated or cratered as a consequence of trauma to the swelling or due to tumor necrosis
- benign proliferation of the surface stratified squamous epithelium produces a papillary, verrucous or warty surface contour
Terms applied to soft tissue enlargements of various shapes and dimensions
- plaque
- papule
- nodule
- tumor
- mass
What is a papule?
Circumscribed solid lesion elevated above level of adjacent mucosa not more than 5 mm in diameter
What is a nodule?
Circumscribed solid lesion elevated above level of adjacent mucosa more than 5 mm in diameter (some texts say more than 1 cm in diameter)
Note: the surface may be smooth, cratered (a raised lesion having a central cavity), or verrucous (warty or cauliflower in appearance)
What is a tumor?
A solid growth more than 1 cm in diameter or any solid growth or a neoplastic growth.
What is a mass?
Non-specific term for enlargement or surface swelling.
Where do benign encapsulated neoplasms lie?
within connective tissue
Mobility of solid lesions is due to what?
Lining (non-keratinized) mucosa has an underlying submucosa; therefore the mucosa can be moved over the surface of a submucosal encapsulated tumor in these areas.
Describe the mobility of solid lesions of the lining mucosa on the ventral surface of the tongue
Lining mucosa on the ventral surface of the tongue cannot be moved over the surface of a tumor because the submucosa is scanty or absent.
Mobility of tumors in masticatory (keratinized) mucosa
- Masticatory mucosa cannot be moved over the surface of tumor on the anterior dorsum of the tongue where there is no submucosa.
- Masticatory mucosa cannot be moved over the surface of a tumor in the gingivae and palatal raphe because there is no submucosa; there is mucoperiosteum at these sites.
- Even though most of the hard palate possesses a submucosa, the mucosa cannot be moved over surface of a tumor because the mucosa is tied down along its borders on both sides by mucoperiosteum.
Where do reactive enlargements arise?
- Recall reactive enlargements are proliferations in response to local irritation.
- They arise from the connective tissue of the lamina propria and remain attached to it.
Describe mobility of reactive enlargements?
Not movable between adjacent tissue layers
What neoplasms are fixed or attached to adjacent connective tissue or adjacent structures?
- Unencapsulated benign neoplasms
- Malignant neoplasms
- typically infiltrate or invade surrounding connective tissue, skeletal muscle, and bone
How are blisters created?
Created by the accumulation of fluid within surface stratified squamous epithelium or at the junction of the epithelium with underlying lamina propria.
Blister-like lesions include
vesicles, bullae, and pustules
What is a vesicle?
a fluid-filled cavity (or blister) smaller than 5 mm in diameter in the mucosa (forming within or below the stratified squamous epithelium)
What is a bullae?
A fluid-filled cavity larger than 5 mm in diameter, within or below epithelium
What is a pustule?
A vesicle or bullae containing pus, within or below epithelium.
What is fluctuance?
- When gentle digital pressure is applied to one side of a swelling, a wave passes through the lesion and is detectable by fingers placed on the far side.
- Most often in cysts or pseudocysts containing fluid or semisolid material.
Consistency of fluid-filled lesions
Soft in consistency, in contrast to solid enlargements which range in consistency from soft (easily compressible) to hard (indurated).
When are soft enlargements containing fluid or semisolid material fluctuant?
They are often fluctuant when they are more than 1 cm in diameter in a superficial location.
Fluctuance is often detectable in…
- fluid-filled cysts
- pseudocysts
- abscesses
- vascular swellings
What are doughy in consistency and are frequently fluctuant?
Cysts containing semi-solid material (such as keratin)
An abnormal cavity containing fluid (or keratin) lined by epithelium
true cyst
An abnormal cavity containing fluid lined by compressed granulation tissue
pseudocyst
Abnormal cavity containing puss
abscess
Color of blood-filled vascular enlargements
- red or blue
* often blanch when pressure is applied and return to their original color when the pressure is released
What is blanching?
Red or blue, blood-filled vascular enlargements become pale when pressure is applied and return to their original color when pressure is released.
What is diascopy?
Use of a glass slide to exhibit blanching.
Consistency of lesions composed of adipose tissue…
soft
