ESPE Abstracts

A 15-year-old boy, an active sportsperson, presented to an orthopaedic surgeon with a painful left elbow. He had no history of preceding trauma, had full range of motion of his elbow and was systemically well. Imaging demonstrated extra articular calcification at the distal humerus. Serum phosphate was elevated at 2.53mmol/l [1.10-1.80] with calcium 2.48mmol/l [2.10-2.60] and tubular reabsorption of phosphate of 94.6% [82-100%]. He was then referred for endocrine assessment, where a history of short tooth roots was elicited. A diagnosis of hyperphosphatemia due to a mutation in GALNT3 was suspected. Dietary phosphate restriction was commenced. Additional investigations revealed a 9mm of calcification medial to the greater tuberosity of left hip and nephrocalcinosis on renal ultrasound. A phosphate binder (Sevalmer) was added, aiming to reduce calcification. Over the following eight months, significant enlargement of the elbow lesion occurred, with worsening pain, reduced mobility limiting sporting activity, accompanied by deterioration of mental health. Serum phosphate remained elevated 2.22 mmol/Lwith a calcium in the normal range 2.31 nmol/l, low FGF23 13.6 ng/l [23.2 – 95.4 ng/L] with tubular reabsorption of phosphate 98.04% [82-100%]. Radiologic imaging confirmed significant increase in calcification at both left elbow and left hip. Surgical resection was undertaken, due to worsening symptoms with marked joint restriction. Other medical interventions being trialled or considered include acetazolamide (carbonic anhydrase inhibitor), NSAIDS or glucocorticoid as anti-inflammatory agents, IL1 blockade (Anakinra), Monoclonal antibody against IL-1Beta or anti-mineralisation therapies with sodium thiosulfate. Hyperphosphatemia Familial Tumoral Calcinosis is a rare, disabling disorder characterised by ectopic calcifications, painful swellings and enamel hypoplasia with bulbous tooth roots (1, 2). Periarticular calcification leads to pain, reduced range of movement and impaired physical function(1). It is caused by autosomal recessive inheritance of a pathological variant in either the gene encoding FGF23, GALNT3 or KLOTHO (1-3), with resultant deficiency of/or resistance to the phosphate regulating hormone fibroblast growth factor 23(1,3). Less common features include small vessel calcification, testicular microlithiasis and angioid streaks of the retina(1-3). The case underlines the importance of a careful history, the unusual history of short tooth roots enabling rapid confirmation of the genetic diagnosis. The main aim of treatment is to reduce serum and urinary phosphate and to reduce pain, though there is no definitive cure (1, 4). Lesion resection is reserved for where the condition affects activity of daily living but may have variable outcomes (3, 4).