Bone Abstracts

Background: Osteoporosis in otherwise healthy children demands thorough study as it may be the first manifestation of an occult illness. When other diseases can be ruled out, juvenile idiopathic osteoporosis (JIO) is the purported diagnosis.

Presentation

We report the case of an 8-year -old boy with no personal or family history of chronic disease who presented with sudden ankle pain unrelated to trauma and not responsive to rest and ibuprofen treatment. Physical examination revealed no abnormalities other than ankle tenderness. X-ray showed a distal tibial fracture after which DEXA was performed and a lumbar bone mineral density (BMD) of 0.541 g/cm² (Z-score −1.7) was found. Basic haematological, biochemical and endocrine determinations were within normal ranges except for vitamin D. The patient was discharged with supplementation and a 6-month follow-up was scheduled, at the time of which he was unable to walk or stand because of leg pain. He was admitted and new tests performed included renal function, rheumatological and bone turnover markers, with no significant alterations. X-rays found an asymptomatic fracture of the wrist, platyspondilia of lumbar vertebrae and a ‘salt-and-pepper’ image of the skull. Lumbar MRI confirmed lumbar deformities but showed no signs of radicular lesion. New DEXA showed a BMD of 0.448 g/cm² (Z-score −2.8, −17.8% from previous). Bone SPECT found no new bone lesions suggesting tumoral activity. Bone marrow aspirate revealed normal cellularity, bone biopsy showed diminished number and thickness of bone trabeculae. Eventually the diagnosis of JIO was established and he received a 3-day treatment with i.v. pamidronate prior to discharge. 4 and 8 months later, BMD Z-scores were −2.4 and −1.5 with no further treatment required. The patient regained full mobility as pain subsided and he had a moderate linear catch-up growth during the following year.

Conclusions: JIO is a rare disease of unknown cause presenting in prepubertal children, often self-limited and with spontaneous resolution, treatment is focused mainly on preventing bone deformation, particularly scoliosis. Biphosphonate treatment may be attempted, as in this case, to hasten recovery.