Diagnosis of Paget's Disease of Bone

Paget's disease of bone (also known as osteitis deformans) is a nonmalignant disease involving accelerated bone resorption followed by deposition of dense, chaotic, and ineffectively mineralized bone matrix.

An estimated 70% of patients who have Paget's disease have no symptoms. The diagnosis is typically found incidentally on radiographs and laboratory investigations. Clinical manifestations, when present, may be wide in spectrum.

Symptoms of Paget's Disease

• Bone pain from microfractures or osteoarthritis; if the jaw is involved, teeth may become loose
• Headaches and loss of hearing or vision from pressure on nerves, brain, or spinal cord and reduced blood flow
• Pain or neuropathy from pressure on nerves
• Increased head size, bowing of a limb, or curvature of the spine
• Hip pain
• Damage to cartilage of joints, which may lead to osteoarthritis
• Heart failure (only in severe cases, especially in patients with heart disease)
• Kidney stones (more common in patients with Paget's disease)
• Sarcoma, in less than 1% of patients with Paget's disease

Patients with bone pain caused by Paget's disease usually describe the pain as continuous. Unlike osteoarthritis, pagetic bone pain usually increases with rest, on weight bearing, when the limbs are warmed, and at night. Paget's disease can cause osteoarthritis if the affected section of bone is near a joint.

A variety of deformities may occur, including kyphosis; shortened or bowed limbs; leonine facies; frontal bossing of the forehead; dental abnormalities; and, in severe cases, an enlarged cranium that may be difficult to hold erect.

Biochemical Markers

There are many biochemical markers for Paget's disease, but the two most important are total serum alkaline phosphatase and urinary pyridinoline. These markers may be normal in patients with the monostotic form of Paget's disease (15% of patients) therefore, serum bone-specific alkaline phosphatase measurements may be useful. Urinary hydroxyproline is no longer considered an accurate marker of activity or extent of the disease.

Radiography

Radiographs include both lytic (early) and sclerotic findings. Many patients are diagnosed incidentally in the asymptomatic phase by plain radiographs that show localized enlargement of bone. These radiographs often have a high specificity because of their classic nature, but a low sensitivity. Bone scans can be used to increase the sensitivity in patients suspected of having Paget's disease; however, the bone scan is less specific and should be interpreted cautiously. Once a diagnosis of Paget's disease is confirmed, repeat radiographs are required only to monitor degeneration around weight-bearing joints. Computed tomography and magnetic resonance imaging are not necessary.

Radiologic Findings in Patients with Paget's Disease

Radiographic

• Osteoporosis circumscripta in skull
• Flame-shaped lesions in long bones
• Osteolytic lesions near thickened lesions
• Sclerotic bone
• Bowed limbs
• Fractures, including “banana” or “chalk” transverse fractures

Bone scintigraphy

• Areas of increased uptake of technetium-99m
• “Mouse face” pattern on scan of affected vertebra

If the results of the biochemical markers and radiography are inconclusive, a biopsy of the affected bone may be indicated in rare cases.

References:

1. Schneider D, Hofmann MT, Peterson JA. Diagnosis and treatment of Paget's disease of bone. Am Fam Physician. 2002 May 15;65(10):2069-72. [Medline]
2. Whyte MP. Clinical practice. Paget's disease of bone. N Engl J Med. 2006 Aug 10;355(6):593-600. [Medline]
3. Ralston SH. Clinical practice. Paget's disease of bone. N Engl J Med. 2013 Feb 14;368(7):644-50. [Medline]