DIAGNOSTIC IMAGING OF OTHER BONE DISEASES

There are many diseases and abnormalities of bone

Some are localized to the jaws while others can affect the whole skeleton

several of the bone diseases described, although totally different in nature, can present very similar appearances radiographically

To differentiate diseases, clinicians need to consider all relevant factors including:

the age of the patient

the distribution of the disease (whether it is generalized or localized)

which bones are involved

the specific radiographic features

The diseases of bone described include:

Developmental or genetic disorders Cleidocranial dysplasia Osteopetrosis

Infective or inflammatory conditions Osteomyelitis Osteoradionecrosis Bisphosphonate-related osteonecrosis of the jaw (BRONJ)

Hormone-related disorders Hyperparathyroidism Acromegaly

Blood dyscrasias Sickle cell anaemia Thalassaemia

Diseases of unknown cause Fibrous dysplasia Paget’s disease of bone

OSTEOPETROSIS (Albers–Schönberg disease)

hereditary disease

characterized by sclerosis of the skeleton (so called marble bones), fragile bones and secondary anaemia

bone formation is normal but bone resorption is reduced, resulting in the presence of excessive calcified tissue and lack of marrow space

Main radiographic features

Evidence in the skull of: A uniformly dense and radiopaque skull vault

Loss of the normal skull markings and structure

Gross thickening and increased opacity of the cranial base with narrowing of the foramina

Occasional involvement of the jaws- always bilateral and includes: Thickening of the lamina dura around the teeth in the early stages

(an almost pathognomonic finding in adults)

Gradual thickening of the trabeculae and a reduction in the size of the marrow spaces producing an overall increase in bone density

Usually normal teeth, but they may be deformed

True lateral skull showing the cranial features of radiopaque, dense vault and thickened base

Right side of a panoramic radiograph showing loss of the normal trabecular pattern and replacement with dense thickened bone

HORMONE- RELATED DISEASES

Hyperparathyroidism

Primary hyperparathyroidism, caused by either hyperplasia or an adenoma of the parathyroids

Secondary hyperparathyroidism caused by kidney disease, results in increased secretion of parathormone

causes generalized skeletal bone resorption leading to osteopenia (generalized decrease in bone density), bone pain or even pathological fracture and raises the plasma calcium levels

Hyperparathyroidism

Localized cyst-like central giant cell lesions (brown tumours) can develop in the jaws and long bones

The term osteitis fibrosa cystica is used to describe severe chronic skeletal hyperparathyroidism following brown tumour degeneration and fibrosis

Brown tumour

Main radiographic features

Evidence in the skull vault of osteopenia producing a fine overall stippled pattern to the bone – hence the description pepper-pot skull

Evidence in the jaws of: Osteopenia (in mandible and maxilla) producing a very fine

trabecular pattern, often described as ground glass

Loss of the lamina dura surrounding all the teeth and thinning or loss of the normal thick cortical bone of the lower border of the mandible

Occasional localized radiolucent cyst-like central giant cell lesions (brown tumours)

Usually normal teeth

„ground glass”

Left side of a panoramic radiograph showing the typical bone changes including loss of the lamina dura, fine ground glass trabecular pattern and thinning of the cortical bone of the lower border and inferior dental canal.

True lateral skull showing the pepper-pot appearance in the skull vault

Periapical showing a radiolucent central giant cell lesion (brown tumour) between the lower incisors, which have been displaced but not apparently resorbed.

Acromegaly

disturbance of bone growth caused by hypersecretion of growth hormone (GH) usually as the result of a pituitary adenoma developing after puberty

Characteristic features include renewed growth of certain bones, particularly the jaws, hands and feet, and overgrowth of some soft tissues

Main radiographic features

Evidence in the skull of: Thickening of the bones of the skull vault which become enlarged and

deformed Enlargement and distortion of the pituitary fossa

Evidence in the jaws of: Enlargement of the mandible; the length of the horizontal and

ascending rami are both increased causing it to become prognathic with an increased obliquity of the angle and with loss of the antegonial notch

The body of the mandible may also be bent or bowed downwards anterior to the angle

Enlargement of the inferior dental canal Thickening and enlargement of the alveolar bone with spacing and

fanning out of the teeth, particularly anteriorly, resulting in an open bite

True lateral skull showing frontal bossing (open white arrow), enlarged pituitary fossa (black arrow), grossly enlarged and prognathic mandible with increased obliquity of the angle

(solid white arrows)

BLOOD DYSCRASIAS

Sickle cell anaemia

hereditary, chronic, haemolytic blood disorder

characterized by abnormal haemoglobin which results in fragile erythrocytes that become sickleshaped under conditions of hypoxia

abnormal red blood cells have a decreased capacity to carry oxygen and are destroyed rapidly, producing anaemia

Main radiographic features

Evidence in the skull vault of:

Thickening of the frontal and parietal bones

Widening of the diploic space

Thinning of the inner and outer tables

Generalized osteoporosis

The hair-on-end appearance

„Hair-on- end”

Main radiographic features

Evidence in the jaws of:

A generalized coarse trabecular pattern, fewer trabeculae are evident and the spaces between them appear larger

The remaining trabeculae between the roots of the teeth can become aligned horizontally to produce a step ladder appearance

Enlargement of the maxillae, with protrusion and separation of the upper anterior teeth

Osteosclerotic areas resulting from the infarcts

Usually normal teeth with normal lamina dura

True lateral skull showing widening of the diploic space and thinning of

the inner and outer tables and early hair-on-end appearance anteriorly (arrowed).

Periapical showing the generalized coarse trabecular pattern in the mandible

Thalassaemia (Cooley’s anaemia)

hereditary haemoglobinopathy is characterized by chronic haemolytic anaemia

The defect lies in an inability to make enough normal globin chains, thus creating abnormal red blood cells which have a shortened life expectancy

the radiographic features result from the bone marrow proliferation required to produce more red blood cells with subsequent remodelling of all affected bones

„squirrel’s face”

Main radiographic features

Evidence in the skull vault of:

Widening of the diploic space

Thinning of the inner and outer tables

Remodelling of the trabeculae to give sparse lines which may radiate outwards from the inner table producing the hair-on-end appearance

Main radiographic features

Evidence in the jaws of:

Generalized coarse trabecular pattern with very large marrow spaces

Expansion, which may lead to encroachment on, and subsequent obliteration of the maxillary antra

Thinning of all cortical structures, most noticeably the lower border of the mandible

Apparent spike-shaped or shortened tooth roots

No evidence of bone infarcts

True lateral skull showing pronounced hair-on-end appearance (black arrows) and involvement of the maxilla with obliteration of the antra

Panoramic radiograph showing the altered trabecular pattern throughout the mandible and maxilla with very large marrow spaces, obliteration of the antra and thinning of the lower border cortex.

DISEASES OF UNKNOWN CAUSE

Fibrous dysplasia

described by the WHO as a genetically based sporadic disease of bone affecting single or multiple bones

Usually develops in childhood and is manifest before the age of ten

characterized by the proliferation of fibrous tissue and resorption of normal bone in one or more localized areas, and subsequent replacement with poorly formed, haphazardly arranged, new bony trabeculae

Clinical varieties include:

Monostotic fibrous dysplasia, characterized by a lesion affecting a single bone, including the jaws, particularly the posterior part of the maxilla

Polystotic fibrous dysplasia, characterized by multiple bone lesions and subdivided into:

Jaffe type, without endocrine disturbances

McCune–Albright syndrome, with endocrine disturbances and skin pigmentation

Café-au-lait

Main radiographic features of monostotic fibrous dysplasia affecting the jaws

A localized rounded zone of relative radiolucency containing a variety of fine trabecular patterns, described as ground glass, fingerprint and orange peel

The more mature the lesion the more radiopaque it appears.

Main radiographic features of monostotic fibrous dysplasia affecting the jaws

Poor definition of the edge of the lesion which merges imperceptibly with the surrounding normal bone

Loss of the lamina dura with thinning of the periodontal ligament shadow

Enlargement of the affected bone

In the maxilla encroachment on, or obliteration of, the antrum and spread into particularly the zygoma and sphenoid bones of the cranial base

Associated teeth occasionally displaced, but rarely resorbed

Periapical showing the overall fine stippled trabecular pattern (orange peel), and loss of the lamina dura around the 16

Lower 90° occlusal centred on the right side, again showing the ground glass appearance and expansion but involving the mandible in the premolar and molar regions (arrowed). The anterior part of the mandible is unaffected.

„ground glass”

„orange peel”

Paget’s disease of bone (osteitis deformans)

In this disease of the elderly, the normal processes of bone deposition and resorption are disturbed severely, but only in certain bones and usually symmetrically

The main features are an enlarged head and thickening of the affected long bones, which bend under stress.

Typically the early stages of the disease are characterized by bone resorption and the later stages by bone deposition, although there is no clear-cut distinction between the two stages

Main radiographic features of early-stage Paget’s disease of bone

In the skull vault, scalloped, circumscribed zones of osteoporosis spreading gradually across the calvarium, described as osteoporosis circumscripta

Involvement of the maxilla and/or the mandible

If either is involved, the whole of the bone concerned shows radiographic changes which include:

Generalized osteoporosis of the affected bones producing a fine trabecular pattern, described as ground glass

Enlargement of the affected bone

Loss of the lamina dura surrounding all the teeth

Main radiographic features of late-stage Paget’s disease of bone

Evidence in the skull vault of:

Haphazard deposition of sclerotic bone in the earlier zones of osteoporosis producing an appearance resembling cottonwool patches

Enlargement and distortion of the shape of the skull including basilar invagination

Main radiographic features of late-stage Paget’s disease of bone

Evidence in the jaws of:

Haphazard deposition of sclerotic bone also resembling cottonwool patches

Enlargement and distortion of the shape of the affected jaw, particularly the alveolus

Encroachment of bone on the sinuses

Separation and displacement of the teeth, often with extensive hypercementosis

Loss of the lamina dura and periodontal ligament shadows