bone diseases4... · 2020-03-19 · bone matrix organic materials (osteoid tissue) 1. collagen...

Bone DiseasesDr: Maii Ibrahim Sholqamy

Lecturer Oral Pathology

Structure of bone

Bone cells

Bone matrix

Periosteum

and endosteum

Bone cells

Bone matrix

Organic Materials (Osteoid Tissue)

1. Collagen fibers type I : arrangement of fibers will

determine the type of bone

2. Ground substance: consist mainly of osteocalcin and

osteonectin.

Inorganic Materials:

Hydroxyapatite crystals of calcium phosphates.

Types of Bone

Lamellar Bones:

1. Compact

Bone

2. Cancellous Bone

Bundle Bone Non lamellar Bone

Woven Bone

Classification of Bone Diseases

1) DEVELOPMENTAL DISEASES

2) ENDOCRINAL DISEASES

3) IDIOPATHIC DISEASES

4) REACTIVE DISEASES

5) FIBRO-OSSEOUS LESIONS:

6) INFLAMMATORY DISEASES: (Periapical granuloma, Periapical

abscess, Osteomyelitis and Dry Socket)

7) NEOPLASTIC

1) DEVELOPMENTAL DISEASES:

1.Cherubism

2.Osteopetrosis

3.Osteogenesis imperfecta

4.Cleidocranial dysplasia

1- Cherubism “ familial fibrous dysplasia “

Definition

Developmental disease that causes bilateral enlargementof the jaws, giving the child a cherubic facial appearance.

The term familial fibrous dysplasia was a poor choice ofearly terminology because this lesion is not a bonedysplasia.

Etiology

Family history is always present (AD)

One mutation found was identified as SH3BP2 onchromosome 4p16.3.

Rare unilateral lesions have been reported.

Clinical pictures:

Age : Children (2-4 years).

Sign: a painless, firm, bilateral enlargement of the lower face.

Both posteriors jaws are involved

Mandible > Maxilla

Bilateral > unilateral

Because children‘s faces are chubby, mild cases may go

undetected until the second decade.

Jaw Swelling leads to difficult in speech and swallowing.

Progressive, extensive bone involvement causes

widening and distortion of alveoli. As a result

1. Developing teeth displaced, delay of eruption.

2. Tooth agenesis

Profound swelling of the

maxilla may result in

stretching of the skin of the

cheeks, which depresses

the lower eyelids, exposing

a thin line of sclera and

causing an eyes raised to

heaven appearance.

(Upward to heaven)

Multilocular radiolucency.

The epicenter is always in the posterior aspect of the

jaws, in the ramus of the mandible or the tuberosity of

the maxilla.

The lesion grows in an anterior direction and in severe

cases can extend almost to the midline.

Causing anterior displacement of teeth.

Radiographic pictures

Only mandible bilateral lesion with thin cortex

Histological features:

The internal structure resembles CGCG, with fine, granular

bone and wispy trabeculae forming a prominent multilocular

pattern.

Composed of fibrovascular CT containing variable number of

multinucleated giant cells.

Some cases may show perivascular eosinophilic cuffing.

An early lesion showing multinucleate

giant cells lying in hemorrhagic fibrous tissue.In a late lesion, there is formation of

woven bone by the fibrous tissue and giant cells are

less numerous. Eventually bone remodeling will

restore the contour and quality of the bone.

2- Osteogenesis Imperfecta (Brittle bone disease)

Definition

A genetically heterogeneous group of heritable defects of

connective tissue. Defect in biosynthesis of type I collagen.

Etiology

Family history is always present

Mutations in the structural genes for the collagen protein

(COL1A2 gene ).

Pathogenesis

Procollagen fails to form a normal alpha helix, polymerize into

normal type 1 collagen

In the bone matrix and the collagen cannot mineralize

Without appropriate matrix, osteoblasts are unable to form

normal amounts of bone, leading to fractures.

Results in bone with:

1. Thin cortex

The bones are thin and lack the usual cortex of compact bone, but

development of epiphyseal cartilages is unimpaired so that bones in

most types can grow to their normal length (normal quantity) .

2. Fine trabeculation

3. Diffuse osteoporosis

This condition may include:

1. Fragile bones,

2. Blue sclerae,

3. Ligament laxity,

4. Hearing loss, and

5. Dentinogenesis imperfecta.

Some affected patients exhibit extreme bone fragility

with numerous fractures and die during the perinatal

period; others suffer only mild bone fragility and live anormal life span.

TYPE I Osteogenesis imperfecta

1. Commonest type Autosomal dominant.

2. Mild to moderate bone fragility

3. Onset is highly variable, may be present at birth also.

4. Hearing loss develops before 30 years.

5. Some patients may show dentinogenesis imperfecta

TYPE II Osteogenesis imperfecta

1. Extreme bone fragility with frequent fractures.

2. Many patients stillborn – 90% die before 4 weeks of

age.

3. Blue sclera present.

4. Dentinogenesis imperfecta present

TYPE III Osteogenesis imperfecta

1. Moderate to severe bone fragility.

2. Blue sclera present in infants but fades by adulthood.

3. Mortality rate higher in older children.

4. Death from cardiopulmonary complications caused

by kyphoscoliosis (backward & lateral curvature of

spine).

Clinical appearance of a severely affected child

with osteogenesis imperfecta type III in which there

is progressive deformity.

The sclera of the eyes appears blue because their

thinness allows the pigment

layer to show through

Leg of an infant with a

severe type of osteogenesis imperfecta

showing severe bending as a result of

multiple fractures under body weight

TYPE IV Osteogenesis imperfecta

1. Mild to moderate bone fragility.

2. Sclera pale in early life, but fades in later life.

3. Fractures present in 50 % case

4. Frequency of fractures decreases after puberty.

5. Some patients may have dentinogenesis imperfecta,

some may not

Histological features

Anomaly due to abnormal collagen synthesis by abnormal

osteoblasts.

Osteoblasts present but bone matrix synthesis is reduced.

Mass of cortical and cancellous bone greatly reduced.

Bone architecture remains immature throughout life.

(woven bone)

Osteoid non mineralized

A section from the vault of the skull of a stillborn infant with type II

disease; the most severe form of osteogenesis imperfecta shows that the bone is small in amount, primitive (woven) in character and

shows no attempt at differentiation into cortical plates and

medullary space.

3- OSTEOPETROSIS (Albers - SchönbergDisease, Marble bone disease)

Definition

Bone disorder characterized by increase in bonedensity due to defect in bone remodeling caused byfailure of normal osteoclast function.

Two clinical types :

1) Infantile Osteopetrosis

2) Adult Osteopetrosis

Etiology and Pathogenesis:

Rare hereditary disease

Osteoclasts fail to function normally.

As a result, bone remodeling is affected.

Defective bone resorption combined with continued bone

deposition results in

1. Thickening of cortical bone and

2. Sclerosis of cancellous bone.

Infantile Osteopetrosis

Clinical Features:

Autosomal recessive trait

Diffusely sclerotic skeleton,

Marrow failure

1) Initial signs – normocytic normochromic anemia

2) Increased susceptibility to infections due to granulocytopenia,

Hepatosplenomegaly

Facial abnormalities :

1) Snub nose,

2) Frontal bossing and

3) Facial deformity leading to hypertelorism

Sclerosis of skull bones :

1) blindness,

2) deafness,

3) facial paralysis

4) signs of cranial nerve compression present.

Dental findings:

1. Congenitally absent teeth and malformed teeth

2. Unerupted teeth and delayed eruption

3. Decreased alveolar bone resorption,

4. Defective and abnormally thickened periodontal ligament,

5. Marked mandibular prognathism

6. Enamel hypoplasia

7. An elevated caries index may be a result of enamelhypoplasia.

8. Osteomyelitis resulting from inadequate host responsebecause of the diminished vascular component of osteopetroticbone.

Osteomyelitis is a serious complication of the disease; it occursmost often in the mandible.

Adult Osteopetrosis

Clinical features:

Autosomal dominant trait

Discovered late in life

Milder symptoms..

About 40% cases are asymptomatic.

Axial skeleton shows sclerosis, while long

bones show little or no defects.

Radiographic features:

Wide spread increase

in bone density.

Distinction between

cortical and cancellous

bone is lost.

Dental X rays – difficult to distinguish roots.

• A generalized increase in radiodensity of the maxilla and mandible multiple remained roots

• The presence of poorly healing extraction sockets in the right lower quadrant with evidence of bony

sequestra circumscribed by an irregular radiolucency were noted, suggestive of a chronic osteomyelitissecondary to osteopetrosis

Histological features:

Several types of abnormal

endosteal formation,

Tortuous lamellar

trabeculae,

Globular amorphous bone

and

Osteophytic bone formation.

2) ENDOCRINAL DISEASES

Hyperparathyroidism (von-Recklinghausen disease of bone) Osteitis fibrosa cystica

Definition:

Increase secretion of parathyroid hormone

Types:

1. Primary,

2. secondary,

3. hereditary.

Etiology:

Primary hyperparathyroidism:

1. One or more hyperplastic parathyroid glands (3%),

2. Parathyroid adenoma (90%) or,

3. An adenocarcinoma (3%)

- Secondary hyperparathyroidism

a compensatory response to hypocalcemia,

1) Renal failure,

2) Renal dialysis,

3) In these patients there is a reduction in vitamin D3, which is

activated in the kidney Intestinal mal absorption

- The hereditary hyperparathyroidism

Noonan-type syndrome

1. an autosomal-dominant condition,

2. Short stature,

3. unusual facies,

4. mental retardation,

5. cardiac defects.

Parathormone hormone

Resorption

Calcium and

phosphorus release to blood

Calcium absorption

Phosphate exertion

Increase calcium

intake by intestinal mucosa

Laboratory findings

Parathormone levels

Calcium

Alkaline phosphatase levels

Phosphate level

Clinical Features

Ranges from asymptomatic cases to severe cases manifesting as

lethargy and occasionally coma.

The incidence increases with age. Greater in postmenopausal women.

Early symptoms:

1. Fatigue, weakness,

2. Nausea, anorexia,

3. Arrhythmias, polyuria,

4. Thirst, depression, constipation.

5. Bone pain and headache.

Several clinical features are associated with the primary form of this disease,

Stones, bones, groans, and moans.

The kidneys, skeletal system, gastrointestinal tract, and

nervous system may be responsible for this syndrome

complex.

- The renal component includes the presence of renal calculi or,

nephrocalcinosis associated with hypercalcemia.

- The increased excretion of calcium leads ultimately to renal stone

formation and renal damage

Bone

Generalized resorption. Subperiostealresorption of the phalanges of the indexand middle fingers

Generalized loss of lamina dura

Loosening of the teeth may also occur,as well as corresponding obfuscation oftrabecular detail and overall corticalthinning.

Expansion of cortex in long standinglesion

Loosening of the teeth may also occur, as well as corresponding

obfuscation of trabecular detail and overall cortical thinning.

- Gastrointestinal manifestations include peptic ulcer

resulting from the increase in gastric acid, pepsin, and serum gastrin levels.

- Rarely, pancreatitis may develop as a result of obstruction

of the smaller pancreatic ducts by calcium deposits.

Neurologic manifestations may become evident when serum

calcium levels are very high, exceeding 16 to 17mg/dl. In

such instances coma or parathyroid crisis may occur.

Loss of memory and depression are common, and, rarely, true

psychosis may appear.

Some of the neurologic findings may be attributed to calcium

deposits in the brain.

Radiographic features

Osteitis fibrosa cystica are the result of significant bone

demineralization, with fibrous replacement producing radiographic

changes that appear cyst-like lesions in the bone

- Loss of LD in primary hyperparathyroidism patient

a well-defined area of

bone loss caused by a

brown tumor

Osteitis fibrosa cystica in the

humerus of the same patient

with a parathyroid adenoma

A periapical view reveals the

relative radiolucency of the bone. There is loss of

lamina dura around the roots, loss of trabeculae

centrally and coarsening of the trabecular pattern

elsewhere

The same patient after

treatment shows improved bone density and

reformation of the

lamina dura and cortex.

Changes may include an osteoporotic appearance of the mandible

and maxilla, reflecting a more generalized resorption. Thin cortex

A- Radiopaque teeth standing out in radiolucent jaw. B- loss of lamina dura and granular ground glass appearance

Pulpal obliteration, with complete calcification of the pulp

chamber and canals, has been reported in association

with secondary hyperparathyroidism.

Histopathology

The bony trabeculae exhibit osteoclastic resorption, as well as

the formation of osteoid trabeculae by large numbers of

osteoblasts.

In these areas a delicate fibro cellular stroma contains numerous

multinucleated giant cells.

Accumulations of hemosiderin and extravasated red blood cells

are also noted.

As a result, the tissues may appear reddish brown, accounting for

the term Brown tumor of hyperparathyroidism. The lesions are

microscopically identical to central giant cell granulomas