This older male had been complaining for a number of years of headache,
back ache, hip and knee pain not uncommon symptoms as we get older. The
diagnosis of Pagets disease of bone is easy to establish once that
diagnosis is under consideration. Given the symptoms suggestive of degenerative
joint disease (DJD) and in the absence of obvious skeletal deformity, the only
clue that had been missed was an elevated alkaline phosphatase, stable at ~
300-400 for a number of years. Once confirmed by bone scan and X-ray, the
management is straightforward a short course of IV bisphosphonate with
the number and duration of infusions dependent on the bisphosphonate selected.
The first treatment usually lowers the phosphatase by 50% or more, and
it is not necessary to keep treating until the level is back to normal. More
aggressive therapy may be appropriate if the baseline phosphatase is in the
thousands. I see no justification for measuring bone-specific alkaline
phosphatase unless, after radiologic confirmation of the diagnosis, the total
alkaline phosphatase is only minimally elevated, and even then, I am not sure
it is necessary. Likewise, there is little indication to measure or monitor
other markers of bone remodeling. Treatment of symptomatic patients is always
indicated. In asymptomatic patients in whom the phosphatase is markedly
elevated (greater than arbitrarily twice the upper limit of the reference
interval), treatment is appropriate. Many patients will require only one course
of IV bisphosphonate, but the phosphatase should be monitored at six monthly
intervals or when symptoms recur, and re-treatment is appropriate if there is
a substantial rise.
The clinical problem in this case is that he does indeed have DJD
secondary to his age and Pagets, and the symptoms did not abate much with
therapy although his alkaline phosphatase returned to just above normal. His
headaches did decrease in frequency and intensity. Hindsight is 20/20 vision,
and noting the elevated phosphatase should have brought this possibility to
attention earlier, but that too might not have made a difference to the outcome
because he did not present with skeletal pain or deformity, just joint aches
and pains. The asymmetry of the DJD is perhaps the only clinical symptom that
might have suggested something beyond simple wear and tear on the joints.
The symptoms and complications of Pagets are a function of the
skeletal parts involved in the disease. When a vertebral body is involved,
neurologic symptoms may occur as the vertebra expands and impinges on the
spinal cord. Metastatic disease may be the first thing that comes to mind when
the spine X-ray is taken because the affected vertebra looks quite abnormal.
Pagets, but not sclerosing metastases as might be seen in prostate
cancer, increases vertebral body dimensions in both the anterior-posterior and
lateral view. Involvement of the proximal femur may present not with joint pain
but intense heat over the affected area. A bowing deformity of one leg is
another indication of possible Pagets again asymmetry is the clue.
In the long bones, Pagets seems to always appear at the end of the bone,
proximal more often than distal, and to my understanding, the lesion never
appears first in the shaft.
Pagets can be a monostotic or polyostotic condition and may be
asymptomatic for some time. When the diagnosis is made as an incidental finding
on an X-ray taken for other reasons, it is worthwhile to proceed to a bone scan
to document the extent of the disease. It is important for you and the patient
to know that it is rare for Pagets to develop in a new skeletal site once
the diagnosis has been established. Should a new skeletal lesion develop, it is
imperative to seek a cause other than Pagets, all too often a metastasis.