Presentation
Patient presented with some stiffness in the ankles over the past few months. Complete metabolic panel revealed elevated alkaline phosphatase 138 IU/L (Normal reference range: 30-110 IU/L).
Patient Data
Axial x-ray of the left calcaneus at first presentation reveals thickened trabeculae and cortices representing Paget's disease.
Lateral x-ray of the calcaneus also shows thickened trabeculae and cortices of the calcaneus. Joint spaces are preserved. Posterior and plantar calcaneal enthesophytes are present.
Lateral x-ray of the left foot after an interval of 9 years shows stable trabecular thickening of the calcaneus. There has been interval development of subtalar osteoarthritis with posterior osteophytes.
Whole body bone scan demonstrates a large area of abnormal increased radiotracer uptake in the left hindfoot. A smaller focus of increased uptake is noted in the right calcaneal region.
Additionally noted are degenerative changes in the bilateral knees, bilateral shoulders, left sternoclavicular joint, and the base of both great toes.
Spot images of the feet demonstrate extensive increased radiotracer uptake throughout the left calcaneus.
Another whole body bone scan after an interval of 3 years once again demonstrates intense increased radiotracer uptake corresponding to the region of the left calcaneus. This uptake was present on the previous study and is unchanged.
Case Discussion
Paget disease is a prevalent skeletal disorder commonly affecting middle-aged and elderly individuals, characterised by abnormal and excessive bone remodelling. It manifests with varying severity and progresses through different phases of activity, followed by periods of inactivity. Radiographic findings of Paget disease are highly indicative, typically presenting with an initial osteolytic phase followed by a more osteosclerotic phase.
Typical features include bone enlargement, increased radiodensity, accentuated trabecular pattern, and deformities. Complications may include pathological fractures, neurological symptoms, skeletal deformities, joint issues, and secondary tumours.
Radiographs, CT and MRI are valuable tools for detecting pagetic bone changes and are particularly effective in diagnosing sarcomatous transformation, which is the most feared complication of this disease 1.
The case shown is a rare example of Paget disease of the calcaneus. This is an active mixed phase of the disease. There is no evidence of malignant transformation, although there is development of adjacent subtalar osteoarthritis.
Case co-author: Sanika Patil (Loyola University Medical Centre)
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