Nigerian Journal of Surgical Research, Vol. 6, No. 1-2, Jan-June, 2004, pp. 73

Letter to the Editor

Diagnosis of Paget’s disease of bone

A. A. Bajomo

Department of Radiology, Olabisi Onabanjo University Teaching Hospital, Sagamu, P. O. Box 2108, Dugbe, Ibadan. E-mail: bayobajomo@yahoo.com

Code Number: sr04023

Currently available diagnostic imaging techniques contrast markedly with the methods of Diagnosis available at the time of Sir James Paget’s documentation of the disorder. ¹ Paget’s used only clinical and pathological information and his classical description has stood the test of time. Recently medical imaging such as computerized tomography and magnestic resonance imaging has led radiology to play a leading role in diagnosis. In most cases diagnosis will be straightforward. Problem may arise however, when the findings are atypical and particularly when the Disease is encountered in younger age groups. ¹

The disease process is generally classified into three main groups, notably osteolytic, mixed and the sclerosed types. The three phases may however be seen in the same patient.  It is generally accepted that the initial stage of Paget’s disease is osteolytic which is reflected as a sharply defined area of lucency. ^2,.3 This phase was originally described in cases of cranial involvement and was termed osteoporosis circumscripta. A similar process may involve long bones, where the advancing edge of the active osteolytic phase often assumes a “V” or “U” shaped margin in the diaphyseal cortex. This is an important diagnostic sign and may be the only clue to the diagnosis of early Paget’s disease. This is particularly so in younger patient⁴ where fusiform lucency expansion of the cortex may occur in the shaft of a long bone (usually tibia). The process is followed by a mixed appearance, which is characterized by enlargement of bone architectural disorganization resulting from periosteal new bone formation and thickening of trabeculae. An inactive sclerotic phase develops later.

In the active osteolytic and osteosclerotic phases uptake of radionuclide is a prominent feature and it has been show to precede the appearance of structural changes in the corresponding radiograph. ⁵ As the disease progresses to the inactive sclerotic phase, scanning may show little or no uptake, but at this stage, the radiological findings are characteristic. ⁶

Computerize tomography (CT) is the most valuable technique for excluding sarcomatous transformation in Paget’s disease. It will also provide detailed information with regard to a soft tissue mass and the presence and extent of bone destruction. ⁷ The axial sections provided by CT are particularly helpful in examining the spine, shoulder and pelvic girdle, where large lesions may otherwise be overlooked on the plain radiographs. It is also useful in confirming the disease in atypical case and in demonstrating the paravertabral soft tissue swelling which is sometimes associated with Paget’s disease and was previously described as extramedullary haemopoesis. ⁸

Magnetic resonance imaging (MRI) of Paget’s disease correlates with the radiographic and CT findings with areas of decreased signal representing the enlarged sclerotic bone. Signal patterns in the medullary cavity vary depending upon the amount of normal marrow, fibrofatty or fibrovascular tissue present. ⁹ MRI is not been used extensively in the management of Paget’s disease although the assessment of neurological complications in one area where it is of help. It remains to be seen what role MRI will play in the future management of Paget’s disease.

A definitive diagnosis can be made on clinicoradiographic finding but the unusual presentation and complication, such as sarcomatous transformation, may require the used of further imaging techniques.

A. A. Bajomo

Department of Radiology, Olabisi Onabanjo University Teaching Hospital, Sagamu, P. O. Box 2108, Dugbe, Ibadan. E-mail: bayobajomo@yahoo.com 

REFERENCES

Copyright 2004 - Nigerian Journal of Surgical Research