Geriatric chronic, progressive thoracic pain: Case discussion

Case history 

A 68-year-old male presented with thoracic pain and a feeling of “heaviness” in his lower thoracic spine, which had been present for several months. He had previously consulted his general practitioner who had ordered imaging of this region to examine it further. The sensation of heaviness and pain had been progressive, though the patient could not recall for how long. In 1977, the patient had been involved in a car accident wherein his car had been hit from behind. In the year prior to presentation, the patient had had a prostatic adenoma of the median lobe removed.

What are the imaging findings? 

Fig. 1 demonstrates an unusual appearance to T11, which is enlarged with thickened cortices, particularly of the superior and inferior end-plates. Additional findings are those of a right thoracolumbar convexity and degenerative disc disease throughout the thoracic spine.

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Figure 1. Anteroposterior (a) lateral (b) digital imaging of the thoracic spine, demonstrating an unusual appearance to T11, which is enlarged with thickened cortices. There is also a right thoracolumbar convexity, and degenerative disc disease throughout the thoracic spine.

In Fig. 2, the close-up of the thoracolumbar junction, the thickened trabeculae affecting T11 can be better appreciated as well as the expansion of the bone, which is not only seen laterally but also posteriorly. The computed tomography (CT) imaging of the thoracic spine in Fig. 3 demonstrates the somewhat disordered appearance of the trabecular bone, particularly in the third and fourth horizontal panels of Fig. 3a (bone window) and in the first and second horizontal panels of Fig. 3b (soft tissue window). Reduction in the thoracic central canal dimension is appreciated, particularly on the bone window images.

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Figure 2. Anteroposterior (a) lateral (b) close-up views of the thoracolumbar junction, where the thickened trabecular bone at T11 can be better appreciated. Bone expansion is not only seen laterally but also posteriorly.

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Figure 3. CT imaging of the thoracic spine showing bone (a) and soft tissue windows (b) where the somewhat disordered appearance of the trabecular bone is appreciated, particularly in the third and fourth horizontal panels of (a) and in the first and second horizontal panels of (b). Reduction in the thoracic central canal dimension is appreciated, particularly on the bone window images. Also of note is a vacuum sign (radiolucent aspect at the level of the disc), which is due to degenerative disc disease.

The disorganised trabecular bone, thickened cortices and mild posterior expansion of bone are better appreciated in the close-up views in Fig. 4. Also of note are the degenerative changes to the right (reading left) T11 costovertebral joint, with subchondral cyst formation, subchondral sclerosis and non-uniform loss of joint space. This may have been as a result of the altered bony architecture and expansion of bone resulting in modification of this articular region.

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Figure 4. Close-up CT view at the level of T11 showing bone (a) and a soft tissue (b) windows, allowing further appreciation of the disorganised trabecular bone, thickened cortex and mild posterior expansion of bone. Also of note, are degenerative changes to the right (reading left) T11 costovertebral joint with subchondral cyst formation, subchondral sclerosis and non-uniform loss of joint space, which may have been as a result of the altered bony architecture and expansion of bone resulting in modification of this articular region.

Based on the history and imaging findings, what is your diagnosis? 

Paget's disease of T11, most likely in stages 2–3, with no imaging evidence of malignant degeneration.

What would your clinical management entail? 

Paget's disease is commonly polyostosic and, therefore any previous imaging of the patient should be examined for evidence of Pagetoid bone. If there is clinical suspicion of Paget's disease of another osseous structure, and imaging has not recently been performed, studies should be considered so as to document current involvement and appearance. As well as imaging studies, laboratory investigations should include testing for hypercalcaemia, increased alkaline phosphatase and elevated levels of hydroxyproline in the urine.

Discussion 

Paget's disease is a progressive disease resulting in bone remodeling, which is relatively common in later life, affecting 3–4% of the population over the age of 55 years and up to 10% of the population over the age of 80 years old, though this depends on the country in question. Male patients are affected more commonly in a 2–1 ratio. The current explanation for the development of Paget's disease is based on a combination of genetic and environmental factors, which result in anarchic osteoclastic activity followed by the deposition of fibrous tissue and disorganized trabeculae and increased but inefficient osteoblastic activity.1

Various aetiologies have been proposed, including exposure to the paramyxovirus, and also familial traits, since it is more likely to occur in another member of the family affected by Paget's disease.2 The resultant bone is softer, being of a lower quality than the original bone. The most commonly radiographically detected bones affected are the femur, pelvis and spine.

Paget's disease is often discovered incidentally, since the majority of patients are asymptomatic; however, if the patient is symptomatic, it is more common that the lower limb is involved and the patient may present with pain and development of a lower limb deformity such as bowing, which is associated with pseudofractures.

Such a patient may demonstrate local tenderness and there may be night pain unrelated to the position of the patient.1 If Paget's disease affects the skull or, indeed, the spine, neurologic compression from the expanding bone may result in a variety of neurologic compressive symptoms that may be the first clinical presentation of Paget's disease, for example increasing hearing loss due to neural compression related to Paget's disease of the skull. Patients affected by Paget's disease of the skull may also complain of headaches.1

Due to the potential for affecting the rate of bone production with resultant hypercalcaemia, cardiovascular and renal symptoms may be the initial reason for consultation with a clinician. Cardiac insufficiency tends to occur when one-third or more of the osseous elements are affected by Paget's disease; in the case of the kidneys, the development of renal stones is a common co-morbidity.

Initially, radiographs of the clinically suspicious region are usually performed; these will demonstrate aggressive bone resorption, which has a characteristic tendency to start from one end of the bone and to work its way to the other extreme limit of the bone, initially affecting the subarticular region before gradually invading the shaft of the bone. As this happens, another characteristic finding is that of a leading point of radiolucency, which has been termed the ‘flame’ or ‘blade of grass’ sign. As the osteolytic process, the first of the four stages of Paget's disease, advances from one end of the bone to the other, the initial region gradually begins to be affected by the second, ‘mixed’ stage, whereby, in addition to the osteolytic process, replacement with fibrous tissue begins. This also results in cortical expansion, thickened cortices and accentuation of the trabecular bone.

Paget's disease is a dynamic process and, as such, it is common to note different stages affecting the same bone. In addition, it is frequent to have several bones affected, each at different stages.

Following the second stage, the third stage consists of a predominantly osteoblastic phase, producing increased density of bone; for example, a vertebra affected by the stage three of Paget's disease, will demonstrate the classic ‘ivory vertebra’, where the entire vertebra is increased in density.3, 4

The final stage that may occur is malignant degeneration, often into an osteosarcoma. Clinically, this is accompanied by rapidly progressive pain in the affected region with an accompanying soft tissue mass. The longer a patient is affected by Paget's disease, the higher the likelihood of developing malignant degeneration.

Magnetic resonance (MR) or CT imaging may be performed, either as the initial imaging or as follow up, in order to further characterize the lesion and also to determine the potential complications, such as vertebral expansion resulting in canal stenosis or malignant degeneration, where the use of MR imaging with contrast is ideal in evaluation of the extent of tumour invasion and differentiation from the unaffected Pagetoid bone.5 Bone scintigraphy may also be used to identify areas of increased metabolic activity; in the spine this has a classical ‘clover’ or ‘heart’ shape appearance.6

Treatment of Paget's disease is, in general, reserved for symptomatic patients. Medical treatment currently consists of giving second or third generation bisphosphonates, which may be effective in reducing patients’ pain.7 Traditionally, salmon calcitonin was used and can still be a fallback for managing patients’ pain. Surgery may be suggested for patients with gross osseous deformities or where bony expansion causes serious compromise; however, this is usually reserved for extreme cases.

Conclusions 

Paget's disease of bone is a condition predominantly affecting the older population and, in most cases, is asymptomatic. It is important for clinicians to be aware of complications, which generally relate to the reduced integrity of osseous structures and compression from associated bone expansion.