CASE 121

By: Dr. Nizar Al-Nakshabandi MD, FRCPC

HISTORY:  Right hip pain and localized tenderness with focal increase in temperature.

What are your findings?

What is the differential diagnosis?

What are the causes?

FINDINGS:

The AP view of the pelvis [A] demonstrates cortical thickening and sclerosis of the right iliopectineal and ischiaopubic lines. Furthermore, there is acetabular protrusio. This is associated with enlargement of the pubic rami and ischium. Bone scintigraphy [B] technetium 99 MDP demonstrate marked increase in uptake in the right side of the pelvis.

DIFFERENTIAL DIAGNOSIS:

·        Paget disease of the bone.

·        Fibrous dysplasia.

·        Hyperostosis.

·        Renal osteodystrophy.

·        Sickle cell anemia.

·        Osteopetrosis.

·        Fluorosis.

DIAGNOSIS:

Paget disease of the bone.

PEARLS AND DISCUSSION:

About 10-15% of males above the age 80 can get this condition. It is more common in Western countries. It is a common bone disorder characterized by excessive abnormal bone remodeling. It frequently affects the pelvis, spine, and skull when it affects the proximal long bones it gives the blade of grass sign.

Etiology is not entirely known but it is thought that it is a disease of the osteoclasts. Paramyxovirus has been associated with genetic susceptibility.

Three phases of the disease are known.

The lytic phase that is predominantly osteoclastic activity.

The mixed active phase where there is osteoclastic and osteoblastic activity.

Sclerotic phase where there is no activity.

Correlate with alkaline phosphatase which is usually high, as well as the urine hydroxy Proline in the urine sample. The calcium and phosphorous levels are normal.

In the skull look for osteoporosis and the cotton-wool appearance. Diploic widening of the calvarial tables is sometimes seen.

In the spine look for picture frame sign as well as squaring of the vertebra. You will see the vertical trabeculation increased in Paget’s disease.

The pelvis findings are well illustrated in this case.

Look for the blade of grass sign in long bones.

Symptomatic patients are treated with bisphosphonate aiming to reduce the bone turnover.

The rare complication is the development of secondary osteosarcoma in less than 1% of the cases. Other complications include congestive heart failure from high output, hyperparathyroidism, and extra medullary hematopoiesis. Weakening of the bone and osteoarthritis can occur.

FURTHER READING:

1.      Smith SE, Murphey MD, Motamedi K et-al. From the archives of the AFIP. Radiologic spectrum of Paget disease of bone and its complications with pathologic correlation. Radiographics. 22 (5): 1191-216. 

2.      Walsh JP. Paget's disease of bone. Med. J. Aust. 2004;181 (5): 262-5. Med. J. Aust. 

3.      Cortis K, Micallef K, Mizzi A. Imaging Paget's disease of bone-from head to toe. Clin Radiol. 2011;66 (7): 662-72.