Asymptomatic Paget's disease of bone in a 62-year-old Nigerian man: three years post-alendronate therapy

Summary

Paget's disease is a chronic and progressive disorder of bone characterized by focal areas of excessive osteoclastic resorption accompanied by a secondary increase in the osteoblastic activity. Paget's disease of bone (PBD) is a rare endocrine disease especially among Africans and Asians. Hence the detection of a case in a middle-aged Nigerian is of interest. We present the case of a 62-year-old Nigerian man in apparent good health who was found to have a markedly elevated serum total alkaline phosphatase (ALP) of 1179 U/l (reference range, 40–115 U/l) 4 years ago during a routine medical check-up in the USA. He had no history suggestive of PDB and also had no known family history of bone disease. Examination findings were not remarkable except for a relatively large head. A repeat ALP in our centre was 902 U/l (reference range, 40–120 U/l). Cranial CT scan showed diffuse cranial vault thickening consistent with Paget's disease which was confirmed by Tc-99m hydroxymethylene diphosphonate. He was placed on 40 mg alendronate tablets daily for 6 months. The patient has remained asymptomatic and has been in continuing biochemical remission during the 3-year follow-up period. The most recent ALP result is 88 U/l (reference range, 30–132 U/l) in April 2015.

Learning points

• Serum total alkaline phosphatase remains a sensitive marker of bone turnover and an isolated increase above the upper limit of normal warrants more intense scrutiny in form of investigations targeted at excluding PD.

• Paget's disease is very rare but can occur in the Africans as seen in this Nigerian man and most patients are asymptomatic.

• Asymptomatic patients can benefit from treatment if disease is active, polyostotic or the lesions are located in bones with future risk of complications such as long bones, vertebrae and skull.

• Bisphosphonates are still the mainstay of treatment and alendronate is a useful therapeutic option for treatment.