Oral pathology

Question 1

5.1 a) What are they two types of fibrous dysplasia?

Answer 1

i) Monostotic and polyostotic

Question 2

5.1 b) Describe the key clinical features of each type of fibrous dysplasia.

Answer 2

i) Monostotic fibrous dysplasia:
(1) This is the commonest fibrous dysplasia; it can affect any bone but if it occurs in the jaws the maxilla is more commonly affected than the mandible.
(2) Usually affects children or adolescents, but may not be diagnosed until later in life.
(3) Fibrous dysplasias are usually painless.
(4) Usually present as a gradual smooth bone swelling.
(5) Radiographs may show a variety of appearances, and is often difficult to tell where the lesions end as there may be a gradual transition to normal bone.
(a) The lesions do not tend to cross suture lines.
(b) Depending on the stage of the condition, the lesions may be radiolucent when they first appear but as time goes on more bony trabeculae appear and the lesions become more mottled and opaque.
(c) They are sometime described as having an orange peel or ground glass appearance.
(d) Teeth may be displaced.
ii) Polyostotic fibrous dysplasia:
(1) Less common than monostotic fibrous dysplasia
(2) Female : male ratio: 3:1
(3) Variable distribution of lesions, but may be confined to one segment of side of the body.
(4) Usually diagnosed in childhood as patients tend to experience pathological fractures.
(5) May be part of the McCune-Albright syndrome, which also includes precocious puberty, skin lesions and some endocrine abnormalities.

Question 3

5.1 c) Describe the key histopathological features of fibrous dysplasia.

Answer 3

i) Normal bone is replaced by fibrous tissue.
ii) Fibrous tissue may be cellular or very fibrous containing collagen fibres.
iii) Immature woven bone within islands in the fibrous tissue, that has the appearance of Chinese characters as it is delicate in appearance and irregular in shape.
iv) The affected bone fuses with normal bone at the margins of the lesion.
v) As the lesions mature, woven bone is replaced by lamellar bone.

Question 4

5.2 a) Which of the following are histopathological features of epithelial dysplasia?
(1) Drop-shaped rete ridges
(2) Nuclear hypochromatism
(3) Decreased mitotic activity
(4) Loss of intercellular adherence
(5) Loss of differentiation
(6) Saw tooth rete ridges
(7) Nuclear pleomorphism
(8) Civatte bodies
(9) Loss of polarity of cells.

Answer 4

i) Drop shaped rete ridges
ii) Loss of intercellular adherence
iii) Loss of differentiation
iv) Nuclear pleomorphism

Question 5

5.2 b) What is the difference between epithelial dysplasia, carcinoma in situ and carcinoma?

Answer 5

i) Epithelial dysplasia is usually graded histopathologically as mild, moderate and severe.
ii) Carcinoma in situ is used do describe severe dysplasia in which the changes are seen in all the layers of the epithelium.
iii) However, the changes are confined to the epithelium in dysplasia and carcinoma in situ, whereas in carcinoma the changes are seen to extend through the basement membrane into the underlying connective tissue.

Question 6

5.2 c) What is the commonest cancer of the oral cavity?

Answer 6

i) Squamous cell carcinoma

Question 7

5.2 d) Give three risk factors for this oral cancer.

Answer 7

i) Alcohol
ii) Tobacco
iii) Betel nut chewing
iv) Human papilloma virus
v) Syphilis
vi) Chronic candida infection.

Question 8

5.2 e) If a patient has a suspicious looking ulcer on the lateral border of their tongue, what type of biopsy would be carried out to aid diagnosis and why, and what should be included in the biopsy?

Answer 8

i) Incisional biopsy. This should include some normal surrounding tissue and a representative portion of the lesion. Incisional biopsies are preferred so that some of the lesion is left to aid the surgeon (who may not have performed the biopsy) should they need to completely remove the lesion at a later date.

Question 9

5.3 a) From the options below select the correct descriptions of giant cell granulomas.
(1) They occur most commonly in the first to third decades/fourth to fifth decades/sixth decade plus.
(2) They are more common in males than females/females than males.
(3) They affect the maxilla/mandible most commonly.
(4) They occur anteriorly/posteriorly most commonly.

Answer 9

i) They occur most commonly in the first to third decades.
ii) They are more common in females than males.
iii) They affect the mandible most commonly.
iv) They occur anteriorly most commonly.

Question 10

5.3 b) Name three pathological features that you might see in a giant cell granuloma.

Answer 10

i) Giant cells (osteoclasts)
ii) Vascular stroma/connective tissue
iii) Spindle shaped cells
iv) Haemosiderin (evidence of bleeding)
v) Fibroblasts and evidence of collagen formation
vi) Osteoid

Question 11

5.3 c) Why would you do blood tests for a patient with giant cell granuloma?

Answer 11

i) Pathologically giant cell granulomas are identical to brown tumours of hyperparathyroidism. Blood tests help to distinguish between the two conditions. The blood chemistry is normal in giant cell granuloma but altered in hyperparathyroidism.

Question 12

5.3 d) What two blood tests would you do and why?

Answer 12

i) Plasma calcium levels – raised in hyperparathyroidism, normal in giant cell granuloma.
ii) Alkaline phosphatase levels – lowered in hyperparathyroidism, normal in giant cell granuloma.
iii) Plasma phosphate levels - lowered in hyperparathyroidism, normal in giant cell granuloma.
iv) Parathyroid hormone levels – raised in hyperparathyroidism, normal in giant cell granuloma.

Question 13

5.3 e) Name two other non-odontogenic benign tumours of bone that affect the jaws.

Answer 13

i) Osteoma
ii) Osteochondroma
iii) Melanotic neuroectodermal tumour

Question 14

5.4 a) What is the definition of a cyst?

Answer 14

i) A cyst is a pathological cavity, not formed by the accumulation of pus, with fluid, semifluid or gaseous contents, and lined by epithelium.

Question 15

5.4 b) Are the following lesions inflammatory/developmental/non-epithelial/neoplastic:
(1) Keratocystic odontogenic tumours (odontogenic keratocysts)
(2) Dentigerous cysts
(3) Radicular cysts
(4) Aneurysmal bone cyst

Answer 15

i) Odontogenic keratocysts = developmental/neoplastic
ii) Dentigerous cysts = developmental
iii) Radicular cysts = inflammatory
iv) Aneurysmal bone cyst = non-epithelial

Question 16

5.4 c) From what are dentigerous cysts thought to arise and why?

Answer 16

i) Dentigerous cysts are attached to an unerupted tooth in the region of the amelocemental junction and so are thought to arise from the remnants of the enamel organ. The internal enamel epithelium lies over the enamel and the external enamel epithelium forms the cyst lining.

Question 17

5.4 d) Where do dentigerous cysts occur most commonly?

Answer 17

i) They are associated with teeth that fail to erupt and so are most commonly associated with mandibular third molars and maxillary permanent canines.

Question 18

5.4 e) Describe what the lining and capsule of a dentigerous cyst would look like histologically.

Answer 18

i) The lining is a thin regular layer composed of stratified squamous epithelium, which may occasionally keratinise. The capsule is composed of collagenous fibrous tissue, which is usually free from inflammatory cells. There may be scattered nests of quiescent odontogenic epithelium.

Question 19

5.5 a) What is the difference between a potentially malignant (premalignant/epithelial precursor) lesion and a potentially malignant (premalignant) condition?

Answer 19

i) A premalignant lesion is a lesion in which carcinoma may develop. A premalignant condition is a condition in which there is a risk of carcinoma developing within the mouth, but not necessarily in the pre-existing lesion.

Question 20

5.5 b) What do you understand by the term leukoplakia?

Answer 20

i) A white patch or plaque that cannot be characterised clinically or pathologically as any other disease and is not associated with any physical or chemical agent except the use of tobacco. It cannot be rubbed off.

Question 21

5.5 c) Put the following lesions in order with the one most likely to become malignant first: A)leukoplakia B) speckled leukoplakia C) erythroplakia

Answer 21

i) Erythroplakia > speckled leukoplakia > leukoplakia.

Question 22

5.5 d) What malignancy would they turn into?

Answer 22

i) Squamous cell carcinoma.

Question 23

5.5 e) At which intraoral sites does oral cancer occur commonly?

Answer 23

i) Floor of mouth
ii) Lateral border of tongue
iii) Retromolar area

Question 24

5.5 f) How does this cancer spread?

Answer 24

i) Direct extension into adjacent tissue.
ii) Metastasis to regional lymph nodes
iii) Late in the disease there may be haematogenous spread.

Question 25

g) What factors would affect survival from oral cancer?

Answer 25

i) Delay in treatment
ii) Size of tumour at presentation
iii) Degree of differentiation of tumour – poorly differentiated worse than well differentiated.
iv) Lymph node spread
v) Distant metastases
vi) Position of tumour – more posterior worse prognosis
vii) Malnutrition
viii) Age, worse with advancing
ix) Males have a worse prognosis compared with females.

Question 26

5.6 a) In which gland do salivary calculi occur most commonly and why?

Answer 26

i) Submandibular salivary gland. This is because of the composition of saliva produced by the gland, and the length and anatomy of the duct.

Question 27

5.6 b) What symptoms might a patient with salivary gland obstruction complain of?

Answer 27

i) Meal time syndrome – they complain of pain and swelling in the region of the gland on seeing, smelling or tasting food. The swelling gradually subsides over time. The gland may also become infected.

Question 28

5.6 c) Are calculi a common cause of dry mouth?

Answer 28

i) No

Question 29

5.6 d) If a salivary calculus is not treated what may happen to the gland and what would it look like histologically?

Answer 29

i) The gland may become infected, and the patient may develop chronic sialadenitis. The dilatation of the ductal system, and hyperplasia of the ductal epithelium and development of squamous metaplasia. There is destruction of the acini which are replaced by fibrous tissue. Histologically, there is chronic inflammatory cell infiltration of glandular parenchyma.

Question 30

5.6 e) What do you understand by the term mucocele. What are the types of mucocele and how do they differ?

Answer 30

i) A mucocele is a cyst of a salivary gland, which commonly forms in the lower lip.
ii) They can be extravasation cysts where the saliva leaks into the surrounding tissues forming a cyst-like space without an epithelial lining.
iii) Much less common are retention cysts, where the saliva remains within the ductal system and the duct dilates to form a cyst, which is lined by epithelium.
iv) A ranula is a mucocele which arises in the floor of the mouth from sublingual salivary gland of the submandibular gland.

Question 31

5.7 a) Fill in the blanks using words from the following lists
Cherubism is inherited as an …A… . It usually affects …B… . Bilateral bony swelling are seen in the …C… and the …D… . Histologically the lesions consist of …E… in vascular …F… .
(1) Sex-linked trait/autosomal recessive trait/autosomal dominant trait
(2) Young children/young adults/middle aged
(3) Tuberosities/ frontal region/maxillae
(4) Angles of the mandible/body of the mandible/symphysis of the mandible
(5) Giant cells/Birbeck granules/Civatte bodies
(6) Connective tissue/epithelium

Answer 31

i) A = Autosomal dominant trait
ii) B = young children
iii) C = maxillae
iv) D = angles of the mandible
v) E = giant cells
vi) F = connective tissue

Cherubism is inherited as an autosomal dominant trait . It usually affects young children. Bilateral bony swelling are seen in the maxilla and the angles of the mandible. Histologically the lesions consist of giant cells in vascular connective tissue.

Question 32

5.7 b) Primary hyperparathyroidism is caused by …A… or adenoma of the …B… . This results in …C… of parathormone, which in turn …D… the plasma …E… level by mobilising calcium. …F… swelling of the jaws can occur. Histologically these lesions have the characteristic of a …G… lesion
(1) Hypoplasia/atrophy/hyperplasia
(2) Pituitary/thyroid/parathyroid
(3) Over-production/reduction
(4) Raises/lowers/depletes
(5) Calcitonin/calcium/vitamin D
(6) Fibrous/cyst-like/granulomatous
(7) Tuberculous/granulomatous/giant cell

Answer 32

i) A = hyperplasia
ii) B = parathyroid
iii) C = overproduction
iv) D = raises
v) E = Calcium
vi) F = Cyst-like
vii) G = Giant cell

Primary hyperparathyroidism is caused by hyperplasia or adenoma of the parathyroids. This results in over-production of parathormone, which in turn raises the plasma calcium level by mobilising calcium. Cyst-like swelling of the jaws can occur. Histologically these lesions have the characteristic of a giant cell lesion.

Question 33

5.7 c) Paget’s disease commonly affect the …A… . Bone resorption and …B… are irregular and exaggerated. This can lead to …C… the foramina and cranial nerve compression. Teeth may show …D… and are often difficult to extract.
(1) Young/middle aged/elderly people
(2) Resorption/Replacement/Reduction
(3) Widening of/narrowing of/compression of
(4) Caries/external resorption/hypercementosis

Answer 33

i) A = elderly people
ii) B = replacement
iii) C = narrowing of
iv) D = hypercementosis

Paget’s disease commonly affect the elderly people. Bone resorption and replacement are irregular and exaggerated. This can lead to narrowing of the foramina and cranial nerve compression. Teeth may show hypercementosis and are often difficult to extract.

Question 34

5.7 d) Osteogenesis imperfecta is also known as …A… . It is usually inherited as a(an) …B… condition. It is due to defective synthesis of type …C… collagen. Patients may have …D… sclera. Bone grow to …E… length, but can be distorted by multiple fractures and result in dwarfism.
(1) Brittle bone/marble bone
(2) Autosomal dominant/autosomal recessive/x-linked
(3) I/II/III/IV
(4) Red/yellow/blue/grey
(5) Normal/reduced

Answer 34

i) A = Brittle bones
ii) B = Autosomal dominant
iii) C = I
iv) D = Blue
v) E = normal

Osteogenesis imperfecta is also known as brittle. It is usually inherited as a(an) autosomal dominant condition. It is due to defective synthesis of type I collagen. Patients may have blue sclera. Bone grow to normal length, but can be distorted by multiple fractures and result in dwarfism.

Question 35

5.8 a) What do you understand by the term Nikolsky’s sign?

Answer 35

i) Nikolsky’s sign is when a vesicle appears on gently stroking the mucosa or skin.

Question 36

5.7 b) Pemphigus vulgaris and mucous membrane pemphigoid are both blistering diseases, which exhibit Nikolsky’s sign. At what level do the blisters occur in the two conditions

Answer 36

i) In pemphigus vulgaris the blisters are intra-epithelial. In mucous membrane pemphigoid they are subepithelial.

Question 37

5.8 c) Why do they occur at this level?

Answer 37

i) The two diseases are autoimmune conditions in which autoantibodies are produced against components of the squamous epithelium of the mucosa (and skin). In pemphigus vulgaris autoantibodies are produced against an intercellular adhesion molecule (desmoglein). This causes the keratinocytes to lose their attachment to each other and vesicles/bullae are formed within the epithelium.
ii) In mucous membrane pemphigoid autoantibodies are produced against a component of the basement membrane which results in subepithelial separation.

Question 38

5.7 d) Immunohistochemistry is often used to diagnose these conditions. What do you understand by this term? What types are there and how do they differ?

Answer 38

i) Immunohistochemistry is a technique in which specific antigens within tissue can be visualised with a light or fluorescent microscope. An antibody is applied to a section of tissue and allowed to bond. The binding site is then visualised by a fluorescent ‘tag’; by means of more antibodies attaching to fluorescent tags or by means of a chemical reaction to produce a colour change. There are two types of immunohistochemistry:
(1) Direct immunohistochemistry – a section of the patient’s tissue is placed on a slide and an antibody against the test antigen is added and allowed to bind. The binding site is then visualised by one of the means as described above.
(2) Indirect immunohistochemistry – a section of normal tissue (not from the patient) is placed on a slide and serum from the patient is added and allowed to bind. An antibody against the suspected autoantibody in the patient’s serum is allowed to bind. The binding site is then visualised by one of the means described above.

Question 39

5.7 e) Molecular biology has a role in pathological diagnosis. Name one molecular biopsy technique.

Answer 39

i) Polymerase chain reaction (PCR)
ii) In situ hybridisation
iii) Northern/Southern/Western blotting

Question 40

5.8 a) What do you understand by the term Nikolsky’s sign?

Answer 40

i) Nikolsky’s sign is when a vesicle appears on gently stroking the mucosa or skin.

Question 41

5.8 b) Pemphigus vulgaris and mucous membrane pemphigoid are both blistering diseases, which exhibit Nikolsky’s sign. At what level do the blisters occur in the two conditions?

Answer 41

i) In pemphigus vulgaris the blisters are intra-epithelial. In mucous membrane pemphigoid they are subepithelial.

Question 42

5.8 c) Why do they occur at this level? (PV and MMP)

Answer 42

i) The two diseases are autoimmune conditions in which autoantibodies are produced against components of the squamous epithelium of the mucosa (and skin). In pemphigus vulgaris autoantibodies are produced against an intercellular adhesion molecule (desmoglein). This causes the keratinocytes to lose their attachment to each other and vesicles/bullae are formed within the epithelium.

ii) In mucous membrane pemphigoid autoantibodies are produced against a component of the basement membrane which results in subepithelial separation.

Question 43

5.8 d) Immunohistochemistry is often used to diagnose these conditions. What do you understand by this term? What types are there and how do they differ?

Answer 43

i) Immunohistochemistry is a technique in which specific antigens within tissue can be visualised with a light or fluorescent microscope. An antibody is applied to a section of tissue and allowed to bond. The binding site is then visualised by a fluorescent ‘tag’; by means of more antibodies attaching to fluorescent tags or by means of a chemical reaction to produce a colour change. There are two types of immunohistochemistry:
(1) Direct immunohistochemistry – a section of the patient’s tissue is placed on a slide and an antibody against the test antigen is added and allowed to bind. The binding site is then visualised by one of the means as described above.

(2) Indirect immunohistochemistry – a section of normal tissue (not from the patient) is placed on a slide and serum from the patient is added and allowed to bind. An antibody against the suspected autoantibody in the patient’s serum is allowed to bind. The binding site is then visualised by one of the means described above.

Question 44

5.8 e) Molecular biology has a role in pathological diagnosis. Name one molecular biopsy technique.

Answer 44

i) Polymerase chain reaction (PCR)
ii) In situ hybridisation
iii) Northern/Southern/Western blotting

Question 45

5.9 a) Match the condition or diagnosis to the histopathological features

i) Lichen planus
ii) Radicular cysts
iii) Herpes simplex infection
iv) Pemphigus vulgaris
v) Adenoid cystic carcinoma
vi) Denture-induced stomatitis
vii) White sponge naevus

Cholesterol clefts
Saw tooth rete ridges
Ballooning degeneration
Acantholysis
Perineural invasion
Acanthoma
Rushton bodies
Gram-positive hyphae
Civatte bodies
Epithelial hyperplasia with basket-weave appearance

Answer 45

i) Lichen planus = Saw tooth rete ridges, Civatte bodies, acanthosis

ii) Radicular cysts = Cholesterol clefts, Rushton bodies

iii) Herpes simplex infection = ballooning degeneration
iv) Pemphigus vulgaris = acantholysis

v) Adenoid cystic carcinoma = perineural invasion

vi) Denture-induced stomatitis = acanthosis, gram-positive hyphae

vii) White sponge naevus = epithelial hyperplasia with basket-weave appearance.

Question 46

5.10 a) From the right column, select the site where the lesions given are most likely to occur

i) Squamous cell carcinoma
ii) Ranula
iii)Ameloblastoma
iv) Kaposi sarcoma
v) Basal cell carcinoma
vii)Mucous extravasation cyst
viii)Erythema migrans
xi) Pleomorphic adenoma
x) Lichen planus of the skin

Upper lip
Lower lip
Dorsum of tongue
Lateral border of the tongue
Angle of mandible
Parotid gland
Skin of face
Flexor surfaces of the wrists
Floor of mouth

Answer 46

i) Squamous cell carcinoma = lateral border of tongue
ii) Ranula = floor of mouth
iii) Ameloblastoma = angle of mandible
iv) Kaposi sarcoma = palata
v) Basal cell carcinoma = skin of face
vi) Mucous extravasation cyst = lower lip
vii) Erythema migrans = dorsum of tongue
viii) Pleomorphic adenoma = parotid gland
ix) Lichen planus of skin = flexor surfaces of the wrists

Question 47

5.12 a) From which structure are keratocystic odontogenic (odontogenic keratocysts) tumours thought to arise?

Answer 47

i) Dental lamina or its remnants
ii) The dental lamina is responsible for the production of odontogenic keratocysts and its epithelial residue is the gland of Serres.

Question 48

b) Why do keratocystic odontogenic tumours (odontogenic keratocysts) have a strong tendency to recur after removal?

Answer 48

i) They are difficult to remove intact due to the thin fragile cyst lining.
ii) They often have ‘daughter’ cysts.
iii) They are multilocular with finger-like extensions within bone.
iv) The keratocystic epithelium proliferates rapidly.
v) The remnants of the dental lamina may produce more lesions.

Question 49

5.12 c) Which age group do they most commonly occur in? (OK)

Answer 49

i) 20-30 years.

Question 50

5.12 d) Which is the most common site of presentation? (OK)

Answer 50

i) Angle of mandible

Question 51

5.12 e) List four characteristic histological features of odontogenic keratocystic tumours.

Answer 51

i) Uniform thickness of epithelium
ii) Flat basement membrane, 5-10 cells thick
iii) Elongated palisaded basal cells
iv) Eosinophilic layer of prekeratin in parakeratinised cyst
v) Orthokeratin formation and well defined granular cell layer in orthokeratinised cysts
vi) Folded cyst lining
vii) Thin fibrous wall

Question 52

5.12 f) What syndrome are odontogenic keratocystic tumours associated with?

Answer 52

i) Basal cell naevus syndrome, Gorlin-Goltz syndrome

Question 53

5.12 g) What are the characteristic facial features in these patients?

Answer 53

i) Frontal and parietal bossing, broad nasal root

Question 54

h) What other lesions do these patients present with in the head and neck?

Answer 54

i) Multiple naevoid basal cell carcinomas.

Question 55

5.13 a) Lichen planus is a chronic inflammatory disease. Which tissue does it commonly affect?

Answer 55

i) Skin and mucous membrane

Question 56

5.13 b) Which age group is commonly affected? OLP

Answer 56

i) Over 40 years

Question 57

5.13 c) Reticular lichen planus and atrophic lichen planus are common clinical presentations. Name two other clinical appearances of lichen planus.

Answer 57

i) Erosive
ii) Papular
iii) Plaque-like
iv) Desquamative gingivitis

Question 58

5.13 d) List four typical histological features of (reticular) lichen planus.

Answer 58

i) Hyperkeratosis/parakeratosis
ii) Saw tooth rete ridges
iii) Band-like lymphoplasmacytic infiltration in the juxta-epithelial lamina propria
iv) Oedema extending into the basal layers resulting in liquefaction degeneration of the basal cell layer
v) Lymphocyte infiltration in to the basal layers of the epithelium and CD8 lymphocytes predominate
vi) Hyaline or Civatte bodies in epithelium.

Question 59

5.13 e) What other histological changes might be seen in the epithelium if the lesion was atrophic.

Answer 59

i) There is thinning and flattening of the epithelium.

Question 60

5.13 f) What serious complication can arise in lichen planus?

Answer 60

i) Malignant change.

Question 61

g) Name another connective tissue disorder that can give rise to intraoral lesions similar to lichen planus.

Answer 61

i) Lupus erythematosus.