LAUSR

A 57-year-old woman was admitted to our department in 2012 due to a painless prominence in the right temple, diplopia and blurred vision of one-year duration. She denied previous trauma or thyroid disease. Moreover, the family history was negative for endocrine disorders. Computed tomography revealed a lesion 38× 47 mm in size characterised by a marked thickening of the frontal bone in the area corresponding to the upper and lateral wall of the right orbit presenting lytic and sclerotic changes. As a result, the right medial rectus and inferior rectus muscles, as well as the right optic nerve were compressed. In the ophthalmic examination, a desaturation of colour vision in the right eye was observed, suggesting the right optic nerve neuropathy. Visual evoked potentials (VEP) analysis revealed a slight deterioration of the signal conduction in the optic pathway. Furthermore, a whole body Tc scintiscan demonstrated a solitary area of increased radiotracer uptake in the right orbit (Fig. 1). In addition, alkaline phosphatase was elevated (225 U/l, normal 35–105), whereas calcium, phosphates and parathyroid hormone levels were within the normal range. Thus, a solitary orbital Paget’s disease (PD) was diagnosed. The case was consulted with an interdisciplinary team comprising an endocrinologist, an ophthalmologist, a neurosurgeon and a laryngologist. Taking into consideration the severity of changes and the patient’s opinion, a decision was made to implement a conservative treatment including close ophthalmic monitoring. A surgery was postponed until possible deterioration of symptoms. The patient has been treated with zoledronic acid at the dose of 5 mg IV per year until 2017. Her alkaline phosphatase decreased to a normal level (46 U/l) 1 year following the first dose administration, and remained stable until the present day. In parallel, an improvement of the patient’s clinical status was observed. The visual acuity slightly improved, while diplopia was no longer present. Hence, a decision was made to continue the pharmacological treatment in order to prevent a further, potentially sight threatening, bone remodelling. The VEP profile remained unchanged throughout the observation period. PD is characterised by a local or generalised increase in bone turnover, followed by a disorganised bone remodelling. Apart from osteoporosis, it constitutes the most common metabolic bone disease, which affects 2–4% of adults over 55 years of age. Nevertheless, the disease is very rarely limited to the orbit [1]. The aetiology of PD is still not fully understood, and comprises both genetic and environmental factors [2]. The treatment of choice is bisphosphonates, in particular zoledronate IV, which results in a long-term suppression of bone turnover [3]. What is more, alkaline phosphatase is the most commonly employed parameter for monitoring the disease activity. Additionally, patients should be regularly followed up to monitor biochemical relapse or the development of complications. In conclusion, orbital PD should be taken into consideration in the differential diagnosis of a patient with diplopia and sight deterioration, particularly if the symptoms are accompanied by a solitary lesion of the orbital wall, presenting an increased radiotracer uptake in a whole body scintiscan. * Ewa Cyranska-Chyrek [email protected]