Two cases of monostotic Paget's disease of bone treated with risedronate

Abstract

Paget's disease of bone is a condition characterized by the occurrence of bone deformities due to focal increase in bone turnover. The incidence of Paget's disease of bone is high in Western countries, but relatively low in Asian countries; the disease is extremely rare in Japan, where many cases remain undiagnosed for prolonged periods of time due to a lack of adequate awareness about the disease. In this article, we report two cases of monostotic Paget's disease of bone. (Case 1) A 74-year-old man with many years' history of elevated serum alkaline phosphatase (ALP) level of undetermined cause, who visited Ide Orthopaedic Clinic for another complaint and was found to have a deformity of the left upper arm. (Case 2) A 46-year-old man who visited his physician for low back pain and was found to have an abnormal opacity in the left proximal femur on plain radiographs; this patient also had an elevated serum ALP level, and was referred to Shikoku Cancer Center with a suspected bone tumor. Based on the results of examinations, including plain radiography, blood tests, magnetic resonance imaging (MRI), computed tomography (CT), and bone scintigraphy, both Case 1 and Case 2 were diagnosed as having Paget's disease of bone. Both were treated with oral risedronate at 17.5 mg daily for 8 weeks. Both showed normalization of the serum ALP level, and improvement of the bone resorption and better-defined cortical bone contours on plain radiographs. However, the serum ALP level increased again after completion of treatment in Case 1.