Beth A Brillante

Fracture Incidence in Polyostotic Fibrous Dysplasia and the McCune‐Albright Syndrome

In patients with polyostotic fibrous dysplasia of bone, the peak incidence of fractures is during the first decade of life, followed by a decrease thereafter. Phosphaturia is associated with an earlier incidence and increased frequency of fractures.

An Instrument to Measure Skeletal Burden and Predict Functional Outcome in Fibrous Dysplasia of Bone

An instrument to measure skeletal burden in fibrous dysplasia was developed. Biological and clinical relevance was shown by correlating skeletal burden scores with bone markers, quality of life, and ambulatory status. Childhood scores predict adult ambulatory status, and scores were unaffected when bone markers decreased with bisphosphonate treatment or aging.

Selective Venous Catheterization for the Localization of Phosphaturic Mesenchymal Tumors

Tumor‐induced osteomalacia (TIO) is characterized by renal phosphate wasting, hypophosphatemia, and aberrant vitamin D3 metabolism and is caused by fibroblast growth factor 23 (FGF‐23)–producing mesenchymal tumors, which are often difficult to locate. We investigated the utility of selective venous sampling in tumor localization. The primary endpoint was identification of the FGF‐23 concentration ratio between the venous drainage of the tumor bed and the general circulation that was diagnostic of the location of an FGF‐23‐secreting tumor. Fourteen subjects underwent 15 sampling procedures after functional and anatomic imaging studies. Subjects fit into three imaging categories: no suspicious site, multiple sites, and single site (positive controls). FGF‐23 levels were measured by ELISA. Suspicious tumors were resected for diagnosis, confirmation, and cure. In subjects with a positive venous sampling study and subsequent cure, a minimum ratio of 1.6 was diagnostic. In 7 of 14 subjects there was suggestive imaging, a diagnostic ratio, and an associated TIO tumor (true positive). Four of these required complicated resection procedures. In 4 of 14 subjects with no suspicious site on imaging studies, an FGF‐23 diagnostic ratio was not detected (true negative). Biopsy or resection of a single lesion in 2 of 14 subjects with a diagnostic ratio failed to identify a TIO tumor (false positive). A diagnostic FGF‐23 ratio was absent in 1 of 14 subjects whose tumor was a single highly suspicious lesion on imaging studies (false negative). These data yield a sensitivity of 0.87 [95% confidence interval (CI) 0.47–0.99] and a specificity of 0.71 (95% CI 0.29–0.96). Selective venous sampling for FGF‐23 was particularly useful in subjects with multiple suspicious sites or an anatomically challenging planned resection but not in the absence of a suspicious lesion on imaging studies.

Onset, Progression, and Plateau of Skeletal Lesions in Fibrous Dysplasia and the Relationship to Functional Outcome†

Most lesions in FD and their attendant functional disability occur within the first decade; 90% of lesions are present by 15 years, and the median age when assistive devices are needed is 7 years. These findings have implications for prognosis and determining the timing and type of therapy.

LONG-TERM OUTCOME OF OPTIC NERVE ENCASEMENT AND OPTIC NERVE DECOMPRESSION IN PATIENTS WITH FIBROUS DYSPLASIA: RISK FACTORS FOR BLINDNESS AND SAFETY OF OBSERVATION

OBJECTIVEFibrous dysplasia (FD) of bone may occur solely as a skeletal condition or it may occur in association with extraskeletal manifestations, including growth hormone (GH) excess. Uncertainty exists as to the management of FD involving the optic nerves. In an effort to clarify management, the authors studied a large population of patients. METHODSOne hundred four patients underwent an evaluation that includedreview of records, endocrine testing, cranial computed tomography, and neuro-ophthalmological examination. RESULTSNinety-one of 104 patients had craniofacial FD; complete records were available for 87 patients (174 nerves). Seventeen percent of the optic nerves were less than 50% encased, 22% were 50 to 99% encased, and 61% were 100% encased. Twelve percent of the nerves that were 100% encased showed evidence of optic neuropathy, but 88% did not. The group with optic neuropathy was not older than the group without. Patients with GH excess were significantly more likely to have nerves that were 100% encased (relative risk, 4.1; 95% confidence interval, 1.5–11.1; P = 0.0017) and to have optic neuropathy (relative risk, 3.8; 95% confidence interval, 2.0–7.1; P = 0.0019). Six prophylactic optic nerve decompressions were performed; in five patients, vision was stable after surgery, and one patient was blind after surgery. Thirteen interventional optic nerve decompression procedures were performed; six of the 13 patients showed some improvement and seven of the 13 showed no improvement or worsened vision. CONCLUSIONThe vast majority of optic nerves encased with FD do not exhibit symptoms of optic neuropathy and seem to be stable over time. GH excess is associated with increased risk of nerve encasement and optic neuropathy. Patients with craniofacial FD should be screened for GH excess, and optic nerve decompression should be performed only when there is objective evidence of progressive optic neuropathy.

Daily Parathyroid Hormone 1-34 Replacement Therapy for Hypoparathyroidism Induces Marked Changes in Bone Turnover and Structure

Parathyroid hormone (PTH) has variable actions on bone. Chronically increased PTH is catabolic and leads to osteoporosis; yet intermittent administration is anabolic and increases bone mass. PTH deficiency is associated with decreased bone remodeling and increased bone mass. However, the effects of PTH replacement therapy on bone in hypoparathyroidism are not well known. We discontinued calcitriol therapy and treated 5 hypoparathyroid subjects (2 adults and 3 adolescents) with synthetic human PTH 1‐34 (hPTH 1‐34), injected two to three times daily for 18 months, with doses individualized to maintain serum calcium at 1.9 to 2.25 mmol/L. Biochemical markers and bone mineral density (BMD) were assessed every 6 months; iliac‐crest biopsies were performed before and after 1 year of treatment. hPTH 1‐34 therapy significantly increased bone markers to supranormal levels. Histomorphometry revealed that treatment dramatically increased cancellous bone volume and trabecular number and decreased trabecular separation. Changes in trabecular width were variable, suggesting that the increase in trabecular number was due to the observed intratrabecular tunneling. Cortical width remained unchanged; however, hPTH 1‐34 treatment increased cortical porosity. Cancellous bone remodeling was also stimulated, inducing significant changes in osteoid, mineralizing surface, and bone formation rate. Similar changes were seen in endocortical and intracortical remodeling. BMD Z‐scores were unchanged at the spine and femoral neck. Total hip Z‐scores increased; however, total body BMD Z‐scores decreased during the first 6 months of treatment and then stabilized, remaining significantly decreased compared to baseline. Radial Z‐scores also decreased with treatment; this was most pronounced in the growing adolescent. Daily hPTH 1‐34 therapy for hypoparathyroidism stimulated bone turnover, increased bone volume, and altered bone structure in the iliac crest. These findings suggest that treatment with hPTH 1‐34 in hypoparathyroid adults and adolescents has varying effects in the different skeletal compartments, leading to an increase in trabecular bone and an apparent trabecularization of cortical bone. Published 2012 American Society for Bone and Mineral Research. This article is a US Government work and, as such, is in the public domain in the United States of America.

Optic neuropathy in McCune-Albright syndrome: effects of early diagnosis and treatment of growth hormone excess.

CONTEXT GH excess is a serious complication of McCune-Albright syndrome (MAS) and has been associated with craniofacial morbidity. OBJECTIVE The aim of the study was to determine whether early diagnosis and treatment of MAS-associated GH excess prevents optic neuropathy and hearing impairment, the major morbidities associated with GH excess. DESIGN AND SETTING A retrospective cross-sectional analysis was conducted at a clinical research center. PATIENTS Twenty-two subjects with MAS-associated GH excess and 21 control MAS subjects without GH excess were included in the study. INTERVENTION Biochemical testing included random GH, nadir GH after glucose load, nadir GH on frequent sampling, and IGF-I Z-score. Subjects underwent imaging, ophthalmological, audiological, and otolaryngological assessment. Treatment included octreotide, pegvisomant, transphenoidal surgery, and/or radiotherapy as indicated. MAIN OUTCOME MEASURE Association of optic neuropathy and hearing impairment to age at GH excess diagnosis/treatment was measured. RESULTS Of 129 MAS subjects, 26 (20%) were diagnosed with GH excess based on elevation of two measures of GH function. Of these, 22 subjects were candidates for pharmacological intervention. Optic neuropathy was significantly correlated with intervention status, with no cases in the early intervention group (diagnosed/treated before age 18) or the control group, and four of seven (57%) in the late intervention group (diagnosed/treated after age 18) (Fishers exact test; odds ratio, 0.027; P = 0.0058). Early diagnosis/intervention was not associated with reduction in hearing deficits (odds ratio, 1.25; P = 1.00). Mean head circumference SD score was significantly higher in the late (6.08; range, 2.70 to 22.56) than the early intervention (2.67; range, -0.65 to 6.72) or control groups (2.13; range, -2.06 to 7.79) (P = 0.003). CONCLUSIONS Early diagnosis/treatment of GH excess in MAS is important to prevent optic neuropathy and craniofacial expansion. The relationship between hearing deficits and GH excess remains less clear and requires further study.

A randomized, double blind, placebo-controlled trial of alendronate treatment for fibrous dysplasia of bone.

CONTEXT Fibrous dysplasia (FD) is a rare skeletal disorder, resulting in deformity, fracture, functional impairment, and pain. Bisphosphonates have been advocated as a potential treatment. OBJECTIVE To determine the efficacy of alendronate for treatment of FD. DESIGN Two-year randomized, double-blind, placebo-controlled trial. SETTING Clinical research center. PATIENTS Forty subjects with polyostotic FD (24 adults, 16 children). Subjects were randomized and stratified by age. INTERVENTIONS Study drug was administered over a 24 month period in 6 month cycles (6 months on, 6 months off). Alendronate dosing was stratified: 40 mg daily for subjects >50 kg, 20 mg for 30-50 kg, 10 mg for 20-30 kg. MAIN OUTCOME MEASURES Primary endpoints were bone turnover markers, including serum osteocalcin, and urinary NTX-telopeptides. Secondary endpoints included areal bone mineral density (aBMD), pain, skeletal disease burden score, and functional parameters including the 9-min walk test and manual muscle testing. RESULTS Clinical data was collected on 35 subjects who completed the study. There was a decline in NTX-telopeptides in the alendronate group (P = .006), but no significant difference in osteocalcin between groups. The alendronate group had an increase in areal BMD in normal bone at the lumbar spine (P = .006), and in predetermined regions of FD (P < .001). There were no significant differences in pain scores, skeletal disease burden scores, or functional parameters between the groups. CONCLUSIONS Alendronate treatment led to a reduction in the bone resorption marker NTX-telopeptides, and improvement in aBMD, but no significant effect on serum osteocalcin, pain, or functional parameters.

The correlation of specific orthopaedic features of polyostotic fibrous dysplasia with functional outcome scores in children.

BACKGROUND Polyostotic fibrous dysplasia has a wide clinical spectrum, with substantial variation between patients in terms of orthopaedic manifestations, including the number of fractures, the degree of deformity of the limbs, and the presence of scoliosis. Data from bone scans, skeletal surveys, and records were correlated with the Pediatric Outcomes Data Collection Instrument scales to examine whether any specific facet of orthopaedic involvement could be related to functional abilities. METHODS All patients who were sixteen years of age or younger and who were part of an ongoing natural history study of polyostotic fibrous dysplasia (including McCune-Albright syndrome) were sent an age-appropriate Pediatric Outcomes Data Collection Instrument outcomes tool. The medical records and radiographs of the patients who returned forms were reviewed. Radiographic measurements of scoliosis, the femoral neck-shaft angle, and limb deformities were then performed. The extent of skeletal involvement with polyostotic fibrous dysplasia (disease burden) was assessed on bone scans with use of a validated tool. A chart review was performed to determine the fracture rate, the use of bisphosphonates, and the endocrine status. These measurements were correlated with the Pediatric Outcomes Data Collection Instrument scores. RESULTS The outcomes tool was sent to twenty-seven patients and the completed instrument was returned by twenty patients, for a response rate of 74%. The parent-child form was filled out for twelve patients and the parent-adolescent form was filled out for eight patients. The mean standardized Pediatric Outcomes Data Collection Instrument scores for all twenty patients were lowest for sports (62; range, 14 to 100) and happiness (72; range, 25 to 100). Adolescents and parents disagreed with regard to sports (with adolescent scores being higher than parental scores) and pain (with parental scores being higher than adolescent scores). However, the overall global scores correlated well between the parents and the adolescents (r = 0.78, p = 0.03). The femoral neck-shaft angle correlated strongly with the Pediatric Outcomes Data Collection Instrument score for sports (r = 0.46, p = 0.03) but not for transfers. The bone scan scores for the lower extremity disease burden correlated with both the transfer scale (r = 0.76, p = 0.03) and the sports scale (r = 0.77, p = 0.02). Deformity of the limbs, the presence of scoliosis, the prevalence of endocrine dysfunction, and the number of fractures did not correlate with the Pediatric Outcomes Data Collection Instrument scores. CONCLUSIONS In patients with polyostotic fibrous dysplasia, the loss of the normal femoral neck-shaft angle and the disease burden in the lower extremities appear to have the greatest effect on functional activity as measured with the Pediatric Outcomes Data Collection Instrument tool.

Phenotypic and Genotypic Characterization and Treatment of a Cohort With Familial Tumoral Calcinosis/Hyperostosis-Hyperphosphatemia Syndrome

Familial tumoral calcinosis (FTC)/hyperostosis‐hyperphosphatemia syndrome (HHS) is a rare disorder caused by mutations in the genes encoding fibroblast growth factor‐23 (FGF23), N‐acetylgalactosaminyltransferase 3 (GALNT3), or KLOTHO. The result is functional deficiency of, or resistance to, intact FGF23 (iFGF23), causing hyperphosphatemia, increased renal tubular reabsorption of phosphorus (TRP), elevated or inappropriately normal 1,25‐dihydroxyvitamin D3 (1,25D), ectopic calcifications, and/or diaphyseal hyperostosis. Eight subjects with FTC/HHS were studied and treated. Clinical manifestations varied, even within families, ranging from asymptomatic to large, disabling calcifications. All subjects had hyperphosphatemia, increased TRP, and elevated or inappropriately normal 1,25D. C‐terminal FGF23 was markedly elevated whereas iFGF23 was comparatively low, consistent with increased FGF23 cleavage. Radiographs ranged from diaphyseal hyperostosis to massive calcification. Two subjects with severe calcifications also had overwhelming systemic inflammation and elevated C‐reactive protein (CRP). GALNT3 mutations were identified in seven subjects; no causative mutation was found in the eighth. Biopsies from four subjects showed ectopic calcification and chronic inflammation, with areas of heterotopic ossification observed in one subject. Treatment with low phosphate diet, phosphate binders, and phosphaturia‐inducing therapies was prescribed with variable response. One subject experienced complete resolution of a calcific mass after 13 months of medical treatment. In the two subjects with systemic inflammation, interleukin‐1 (IL‐1) antagonists significantly decreased CRP levels with resolution of calcinosis cutis and perilesional inflammation in one subject and improvement of overall well‐being in both subjects. This cohort expands the phenotype and genotype of FTC/HHS and demonstrates the range of clinical manifestations despite similar biochemical profiles and genetic mutations. Overwhelming systemic inflammation has not been described previously in FTC/HHS; the response to IL‐1 antagonists suggests that anti‐inflammatory drugs may be useful adjuvants. In addition, this is the first description of heterotopic ossification reported in FTC/HHS, possibly mediated by the adjacent inflammation.