Spectrum and natural history of fibrous dysplasia of bone

Patients With Isolated Craniofacial Dysplasia Report Better Quality of Life Compared With Those With Craniofacial Dysplasia and Extracranial Involvement

PURPOSE

Craniofacial fibrous dysplasia (CFD) is a subtype of fibrous dysplasia/McCune-Albright syndrome (FD/MAS) characterized by FD lesions in one or more of the skull bones. The orbit is often involved, with facial pain, facial deformity, and increased risk of compressive optic neuropathy as associated clinical manifestations possibly leading to altered illness perceptions and impairments in quality of life(QoL). The aim of this study was to evaluate illness perceptions and QoL in patients with CFD among our FD/MAS cohort.

METHODS

One hundred ninety-one patients were included. Illness perceptions and QoL were assessed by using validated questionnaires, that is, the Illness Perceptions Questionnaire-Revised and the Short-Form 36. Patients were first grouped as CFD versus non-CFD, a second selection was based on the presence of "Isolated CFD" versus "CFD+PFD/MAS." Non-CFD patients were grouped as monostotic fibrous dysplasia "MFD" versus polyostotic "PFD/MAS."

RESULTS

Patients with isolated CFD attributed less symptoms to their disease compared with patients with CFD+PFD/MAS (p < 0.05). Furthermore, patients with isolated CFD reported better QoL on all domains (except role emotional and mental health) compared with patients with CFD+PFD/MAS (p < 0.05). Patients with isolated CFD also reported better QoL compared with non-CFD groups (on 3 out of 8 subscales) (p < 0.05).

CONCLUSIONS

Patients with isolated CFD attribute less symptoms to their disease and report better QoL compared with patients with CFD with extracranial involvement or FD without cranial involvement. These findings indicate that craniofacial involvement alone is not sufficient to cause negative illness perceptions and impairments in QoL. Therefore, it can be postulated that isolated CFD should be considered a unique patient subtype within the spectrum of FD/MAS patients.

First application of three-dimensional designing total hip arthroplasty with long uncemented stem for fibrous dysplasia patients combined with hip joint osteoarthritis

Background

In order to treat proximal femur fibrous dysplasia (FD) patients combined with hip joint osteoarthritis (OA), the three-dimensional (3D) designing osteotomy and implantation of femoral component was firstly used for deformity correction and total hip arthroplasty (THA). The purpose is to present the detailed design, perioperative management and evaluate short-term clinical outcomes of this novel therapeutic method.

Method

A retrospective study was performed in twelve FD patients combined with hip joint OA who were treated in our hospital between July 2013 and April 2015. Seven patients received 3D designing combined osteotomy and THA, and the other five patients underwent 3D designing THA only.

Results

All patients were followed-up with an average duration of 47 months (range, 35–56 months). There was no infection, dislocation, postoperative wound problems or mechanical failures. For the seven patients receiving 3D designing corrective osteotomy, the mean extremity lengthening was 2.8 (range, 1.5–4) cm. The average duration of bone union was 4.2 months. The average Harris Hip Score was improved from 46.08 (range, 13–67) points preoperatively to 93.72 (range, 83–100) points at the last follow-up. The average modified criteria of Guille was improved from 3.2 (range, 1–7) points preoperatively to 8.6 (range, 6–10) points at the last follow-up.

Conclusions

The 3D designing THA with long uncemented stem, including 3D designing corrective osteotomy and implantation of long prosthesis stem, seems to be a reliable method for FD patients combined with hip joint OA. Through preoperative 3D design, corrective osteotomy and implantation of long prosthesis stem can be precise to re-store alignment, uttermost preserve host bone, obtain primary stem stability and provide necessary condition for long-term stem survival, finally leading to better limb function. Besides, perioperative management should be abided strictly for late stability. Nevertheless, the outcomes of long-term follow-up and larger cases are still required.

Orthodontic treatment of patient with maxillofacial fibrous dysplasia: A case report

Fibrous dysplasia is a benign skeletal disorder in which the normal bone and marrow are replaced by fibrous tissue and haphazardly distributed woven bone. The aim of this case report is to discuss the orthodontic treatment of a 13-year-old patient with fibrous dysplasia in the left maxilla. The patient had rotated maxillary second premolars, moderate crowding in both maxillary and mandibular arches with low maxillary frenal attachment. Orthodontic treatment was done with full fixed appliance and extraction of maxillary and mandibular third molars. Maxillary frenectomy and free gingival graft in mandibular anterior region were performed by a periodontist. The oral and maxillofacial surgery team monitored fibrous dysplasia in the left maxilla on a yearly interval. There is very limited information about orthodontic management of patients with craniofacial fibrous dysplasia. This case report discusses the orthodontic treatment and the importance of interdisciplinary approach in the management of patient with maxillofacial fibrous dysplasia.

Key words:Orthodontic treatment, fibrous dysplasia, maxillofacial fibrous dysplasia, case report.

Prevalence and Clinical Features of Mazabraud Syndrome: A Multicenter European Study

BACKGROUND

Mazabraud syndrome is a rare disorder, characterized by the presence of fibrous dysplasia (FD) with associated intramuscular myxomas. Data are scarce on the prevalence, clinical features, and natural history of this disorder and outcomes. In this multicenter study, we evaluated a series of patients from 6 European centers.

METHODS

All centers affiliated with the European Musculo-Skeletal Oncology Society (EMSOS) were invited to include data on all patients with Mazabraud syndrome who were seen between 1980 and 2015. The study investigated the prevalence of Mazabraud syndrome, the type, severity, and localization of FD lesions in relation to myxomas, the histopathology of myxomas, and results of GNAS-mutation analysis, when available.

RESULTS

Thirty-two patients (22 female) from 6 centers were included. The prevalence of Mazabraud syndrome was 2.2% in the combined cohort of 1,446 patients with FD, and the syndrome was diagnosed at a mean of 10.1 years after diagnosis of FD. The myxomas were predominantly localized in the upper leg. Excision was performed in 20 patients, recurrence occurred in 6 of these patients (30%) at a median of 8.5 years (range, 1.9 to 16.0 years), and revision surgery was necessary in 5 (25%). High cellularity of myxomas was associated with recurrence (p < 0.05). A GNAS mutation was identified in the myxoma tissue of 5 (83%) of 6 patients with GNAS-mutation analysis.

CONCLUSIONS

This study is the first, to our knowledge, to provide data on the prevalence of Mazabraud syndrome in a relatively large cohort. Although the outcomes of surgical resection were good, a quarter of the patients required revision surgery despite clear resection margins. High cellularity of myxomas was associated with recurrence. GNAS mutations were identified in 83% (5 of 6), emphasizing the shared origin of FD and myxomas. Our data show that patients with FD who have disproportionate complaints, irrespective of FD type, extent, or severity, should be investigated for the possible presence of myxomas.

LEVEL OF EVIDENCE

Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Alkaline Phosphatase Replacement Therapy for Hypophosphatasia in Development and Practice

Hypophosphatasia (HPP) is an inherited disorder that affects bone and tooth mineralization characterized by low serum alkaline phosphatase. HPP is caused by loss-of-function mutations in the ALPL gene encoding the protein, tissue-nonspecific alkaline phosphatase (TNSALP). TNSALP is expressed by mineralizing cells of the skeleton and dentition and is associated with the mineralization process. Generalized reduction of activity of the TNSALP leads to accumulation of its substrates, including inorganic pyrophosphate (PP_i) that inhibits physiological mineralization. This leads to defective skeletal mineralization, with manifestations including rickets, osteomalacia, fractures, and bone pain, all of which can result in multi-systemic complications with significant morbidity, as well as mortality in severe cases. Dental manifestations are nearly universal among affected individuals and feature most prominently premature loss of deciduous teeth. Management of HPP has been limited to supportive care until the introduction of a TNSALP enzyme replacement therapy (ERT), asfotase alfa (AA). AA ERT has proven to be transformative, improving survival in severely affected infants and increasing overall quality of life in children and adults with HPP. This chapter provides an overview of TNSALP expression and functions, summarizes HPP clinical types and pathologies, discusses early attempts at therapies for HPP, summarizes development of HPP mouse models, reviews design and validation of AA ERT, and provides up-to-date accounts of AA ERT efficacy in clinical trials and case reports, including therapeutic response, adverse effects, limitations, and potential future directions in therapy.

Asfotase alfa treatment for 1 year in a 16 year-old male with severe childhood hypophosphatasia

We describe the clinical outcome of asfotase alfa therapy in a 16-year-old boy with severe childhood hypophosphatasia (HPP), who began therapy at age 15 years. The patient was diagnosed with HPP at age 2 years when he presented with genu varum and premature loss of primary teeth. He had a history of multiple fractures requiring 16 orthopedic surgeries with rod and pin placement in his lower extremities. He had chronic skeletal pain and used cane to ambulate with great difficulty. His height Z score at age 15 years was - 5. He had severe scoliosis and deformity of both legs. Bone radiograph showed hypomineralization and characteristic "tongues" of radiolucency in the distal radius and ulna. His serum alkaline phosphatase level was stable, with elevated serum pyridoxal 5'-phosphate and urine phosphoethanolamine, consistent with HPP. He was started on asfotase alfa 2 mg/kg given subcutaneously thrice weekly. He had marked clinical improvement in mobility with no report of pain after 3 months of treatment. At 6 month, he walked without cane and participated in outdoor activities with peers. Bone radiograph at 6 months showed striking improvement in previous radiolucent areas. At 9 months, his annualized growth velocity was 9.5 cm/year, while growth velocity of arm span was 12 cm/year. However, at 12 months, he was noted to have worsening scoliosis from 60 degrees before therapy to 110 degrees, with a slight decrease in height, necessitating a spinal fusion surgery. In conclusion, treatment with asfotase alfa significantly improved physical function, pain, overall quality of life, and skeletal radiographic findings in this patient. Close monitoring for progression of scoliosis in adolescents with HPP treated with asfotase alfa is recommended.

Polyostotic Fibrous Dysplasia With and Without McCune-Albright Syndrome-Clinical Features in a Nordic Pediatric Cohort

OBJECTIVE

Fibrous dysplasia (FD) presents as skeletal lesions in which normal bone is replaced by abnormal fibrous tissue due to mosaic GNAS mutation. McCune-Albright syndrome (MAS) refers to FD combined with skin (café-au-lait) and endocrine manifestations. This study describes the clinical childhood manifestations of polyostotic FD and MAS in a Nordic cohort.

PATIENTS AND DESIGN

We retrospectively reviewed a cohort of pediatric patients (n = 16) with polyostotic FD with or without MAS diagnosed and followed in two Nordic Pediatric tertiary clinics between 1996 and 2017.

RESULTS

Half of the 16 patients with polyostotic FD presented with MAS. All patients with MAS (n = 8) had café-au-lait spots, and either gonadotropin-independent precocious puberty (PP) (girls; n = 5) or abnormal testicle structure (boys, n = 3). None manifested hyperthyroidism or growth hormone excess. Mild hypophosphatemia was common (11/16), but none had signs of hypophosphatemic rickets. Craniofacial bone involvement was found in 12 patients (75%); in 5 of these, skeletal lesions were limited to craniofacial area. One child with craniofacial disease had lost vision due to optic nerve damage. Eleven (69%) patients had sustained a fracture at FD lesion, over half of them requiring surgical fixation of the fracture, most commonly in the proximal femur. The first symptoms leading to FD/MAS diagnosis included skull/facial asymmetry (n = 4), PP (n = 3), abnormal gait (n = 3), pathologic fracture (n = 3), wide-spread café-au-lait spots (n = 1), headache (n = 1), and vision loss (n = 1).

CONCLUSION

Polyostotic FD and MAS remain diagnostic and therapeutic challenges because of the broad clinical spectrum. Recurrent fractures, pain, and even vision loss may impair the quality of life in children with FD.

Optical Coherence Tomography in the Management of Skull Base Fibrous Dysplasia with Optic Nerve Involvement

BACKGROUND

Fibrous dysplasia (FD) of the skull base can manifest with optic nerve compression. As most patients initially do not experience vision loss, controversy exists whether to proceed with prophylactic surgical decompression or elect for conservative observation. Optical coherence tomography (OCT), a physiologic imaging modality widely used to assess the condition of the retinal nerve fiber layer (RNFL), has been useful in monitoring compressive tumors on the optic nerve. This study evaluated potential use of OCT in management of patients with fibrous dysplasia and optic nerve involvement.

METHODS

Six patients with suspected optic nerve compression who underwent OCT imaging as part of a neuro-ophthalmic examination were reviewed over a 2-year period. Patient records were evaluated for visual examination measures, most notably the presence of optic neuropathy, and radiographic measures on computed tomography. Measures were compared by age-adjusted RNFL thickness (above or below fifth percentile) on OCT imaging.

RESULTS

Two patients were found to have mild optic neuropathy in 1 eye each. Three of 12 eyes fell below the age-adjusted fifth percentile of RNFL thickness. Presence of optic neuropathy was associated with abnormal age-adjusted RNFL thickness but not with optic nerve compression (P = 0.45).

CONCLUSIONS

Abnormal RNFL thickness as measured by OCT better predicted the presence of optic neuropathy than computed tomography alone. OCT may be a valuable imaging modality to monitor patients with fibrous dysplasia for development of optic neuropathy during periods of conservative watchful waiting.

Determinants of impaired quality of life in patients with fibrous dysplasia

Background

Fibrous dysplasia is a rare bone disorder, commonly associated with pain, deformity and fractures, which may significantly impact on quality of life. In this study we evaluate quality of life in patients with fibrous dysplasia using the Short Form-36 and the Brief Pain Inventory questionnaires. Data were compared with those of the general Dutch population.

Results

Out of 138 patients from a cohort of 255 patients with fibrous dysplasia that were sent questionnaires assessing quality of life and pain, the response rate was 70.3%, with 97 patients, predominantly female (65%), completing the questionnaires. Monostotic fibrous dysplasia was predominant (n = 62, 64%). Fibrous dysplasia patients had significantly lower quality of life outcome scores than the general Dutch population for all tested domains of the Short Form-36 except for the “Mental health” and the “Role emotional” domains. More severe forms of fibrous dysplasia, had the more severe Short-Form-36 quality of life outcomes, but there was no significant difference in Brief Pain Inventory domains between different subtypes of fibrous dysplasia. Quality of life was lower in patients with higher disease burden, as reflected by high skeletal burden scores (p = 0.003) and high levels of P1NP (p = 0.002).

Conclusion

We demonstrate impairments in all domains of quality of life, except for ‘Mental health’ and ‘Role emotional’ domains, across the wide spectrum of fibrous dysplasia including its milder forms. We identified high skeletal burden scores, reflecting disease severity, as the most consistent predictor of impaired quality of life. Our findings hold significant clinical implications as they draw attention to the clinically unmet need to address quality of life issues in the management of patients with all subtypes of fibrous dysplasia, including its milder forms.

Prognostic Factors From an Epidemiologic Evaluation of Fibrous Dysplasia of Bone in a Modern Cohort: The FRANCEDYS Study

Fibrous dysplasia of bone (FD) is a rare genetic but sporadic bone disease that can be responsible for bone pain, fracture, and bone deformity. The prognosis may be difficult to establish because of the wide spectrum of disease severity. We have analyzed the data from the French National Reference center for FD. We have established a database from standardized medical records. We have made descriptive statistics of the various forms of FD and examined the prognostic factors by multivariable logistic regression analysis, with a parsimonious stepwise method. The primary outcome was a clinically relevant composite index combining bone pain (visual analogic scale >3) and/or incident fracture. In our modern cohort of 372 patients, the median age at diagnosis was 23 years. The revealing symptom (at a median age of 18 years) was bone pain in 44% of patients and a fracture in 9%, but the diagnosis was fortuitous in 25% of cases. Monostotic forms represented 58% of patients and polyostotic forms 42%. The femur was the most commonly affected bone (44% of patients), followed by the skull (38%). Twelve percent of patients had McCune-Albright syndrome (MAS). With a median duration of follow-up of 7 years among 211 patients, we observed an incidence of fracture of 17% and 51% of patients had no bone pain at the end of follow-up (with or without bisphosphonate therapy). In univariate analysis, younger age at diagnosis, renal phosphate wasting, a polyostotic form, prevalent fracture, and bisphosphonate use were significant predictors. In the multivariate model, the polyostotic form and bisphosphonate use remained significant predictors. In conclusion, in a national referral center for FD, one patient on follow-up out of six had incident fracture. A polyostotic form was the main risk factor of a poorer outcome. © 2016 American Society for Bone and Mineral Research.

Extensive polyostotic fibrous dysplasia evaluated for malignant transformation with99mTc-MDP bone scan and18F-FDG PET/CT

Fibrous dysplasia accounts for approximately 7% of benign bone tumours and is a developmental disorder of unknown aetiology. Malignant transformation has been reported in 0.4% of all cases of fibrous dysplasia, and the use of ¹⁸F-fludeoxyglucose positron emission tomography/CT scan in the evaluation of malignant transformation has not yet been established. A 72-year-old male with a long-standing history of polyostotic fibrous dysplasia presented with chest and back pain and was evaluated with a ^99mTc-methylene diphosphonate bone scan as well as an ¹⁸F-fludeoxyglucose positron emission tomography/CT scan to define the extent of bone involvement and assess for possible malignant transformation. We present the imaging findings as well as the long-term follow-up of this case.

Whole exome sequencing links dental tumor to an autosomal-dominant mutation in ANO5 gene associated with gnathodiaphyseal dysplasia and muscle dystrophies

Tumors of the jaws may represent different human disorders and frequently associate with pathologic bone fractures. In this report, we analyzed two affected siblings from a family of Russian origin, with a history of dental tumors of the jaws, in correspondence to original clinical diagnosis of cementoma consistent with gigantiform cementoma (GC, OMIM: 137575). Whole exome sequencing revealed the heterozygous missense mutation c.1067G > A (p.Cys356Tyr) in ANO5 gene in these patients. To date, autosomal-dominant mutations have been described in the ANO5 gene for gnathodiaphyseal dysplasia (GDD, OMIM: 166260), and multiple recessive mutations have been described in the gene for muscle dystrophies (OMIM: 613319, 611307); the same amino acid (Cys) at the position 356 is mutated in GDD. These genetic data and similar clinical phenotypes demonstrate that the GC and GDD likely represent the same type of bone pathology. Our data illustrate the significance of mutations in single amino-acid position for particular bone tissue pathology. Modifying role of genetic variations in another gene on the severity of the monogenic trait pathology is also suggested. Finally, we propose the model explaining the tissue-specific manifestation of clinically distant bone and muscle diseases linked to mutations in one gene.

Osteoarthritis of the hip in fibrous dysplasia of the proximal femur

Deformity of the proximal femur in fibrous dysplasia leads to deviation of the mechanical axis of the hip, which may lead to the development of secondary osteoarthritis (OA). This study investigated the prevalence and predisposing factors for the development of OA in patients with fibrous dysplasia of the proximal femur. We reviewed the records of 209 patients from our institutional database with fibrous dysplasia of the proximal femur, investigating possible predisposing factors including patient demographics, the extent of the coxa vara deformity, the presence of peri-articular disease, and the overall burden of skeletal disease. Of the 209 patients, 24 (12%) had radiological evidence of OA in the ipsilateral hip. The prevalence was significantly higher in patients with polyostotic fibrous dysplasia compared with those with monostotic disease (p < 0.001). In a subgroup analysis of patients with polyostotic disease, the extent of deformity (quantified using the neck–shaft angle), and the presence of peri-articular disease (whether in the head of the femur or the acetabulum) were significant predictors of osteoarthritis (neck–shaft angle likelihood ratio (LR) = 0.847 per 1° increase, p = 0.004; presence of lesion in the head of the femur LR = 9.947, p = 0.027; presence of lesion in the acetabulum LR = 11.231, p = 0.014).

Our data suggest that patients with polyostotic fibrous dysplasia have a high risk of developing secondary OA of the hips. This risk is higher in patients with peri-articular disease, and those with a more severe deformity of proximal femur.

Cite this article: Bone Joint J 2015;97-B:1007–11.

GNAS Spectrum of Disorders

The GNAS complex locus encodes the alpha-subunit of the stimulatory G protein (Gsα), a ubiquitous signaling protein mediating the actions of many hormones, neurotransmitters, and paracrine/autocrine factors via generation of the second messenger cAMP. GNAS gives rise to other gene products, most of which exhibit exclusively monoallelic expression. In contrast, Gsα is expressed biallelically in most tissues; however, paternal Gsα expression is silenced in a small number of tissues through as-yet-poorly understood mechanisms that involve differential methylation within GNAS. Gsα-coding GNAS mutations that lead to diminished Gsα expression and/or function result in Albright's hereditary osteodystrophy (AHO) with or without hormone resistance, i.e., pseudohypoparathyroidism type-Ia/Ic and pseudo-pseudohypoparathyroidism, respectively. Microdeletions that alter GNAS methylation and, thereby, diminish Gsα expression in tissues in which the paternal Gsα allele is normally silenced also cause hormone resistance, which occurs typically in the absence of AHO, a disorder termed pseudohypoparathyroidism type-Ib. Mutations of GNAS that cause constitutive Gsα signaling are found in patients with McCune-Albright syndrome, fibrous dysplasia of bone, and different endocrine and non-endocrine tumors. Clinical features of these diseases depend significantly on the parental allelic origin of the GNAS mutation, reflecting the tissue-specific paternal Gsα silencing. In this article, we review the pathogenesis and the phenotypes of these human diseases.

Three intragenic suppressors of a GTPase-deficient allele of GNAS associated with McCune-Albright syndrome

Gain-of-function mutations in heterotrimeric G-protein α subunits are associated with a variety of human diseases. McCune-Albright syndrome (MAS) is caused by mutations in GNAS, the gene encoding Gs. Alterations at Arg201 significantly reduce the GTPase activity of the protein, rendering it constitutively active. In this study, we have constructed a library of random mutations in a constitutively active yeast GPA1 gene carrying a mutation homologous to the McCune-Albright allele (Arg297His). Intragenic suppressors found at sites with homology to the human Gs protein were tested for their ability to suppress the constitutive activity of an Arg201His mutation in Gs. Three intragenic suppressors, at Phe142, Arg231, and Leu266, were able to suppress elevated basal cAMP responses caused by Arg201His when expressed in HEK293 cells. A range of amino acid substitutions was introduced at each of these sites to investigate the chemical requirements for intragenic suppression. The ability of Gs proteins carrying the suppressor mutations alone to mediate receptor-induced cAMP production was measured. These results offer potential sites on Gs that could serve as drug targets for MAS therapies.

Dental perspectives in fibrous dysplasia and McCune-Albright syndrome

McCune-Albright syndrome (MAS) is a rare multisystem disorder characterized by the triad of polyostotic fibrous dysplasia (FD), endocrine disorders, and café-au-lait skin pigmentation. Ninety percent of MAS patients have FD lesions in the craniofacial area, resulting in significant orofacial deformity, dental disorders, bone pain, and compromised oral health. Maxillomandibular FD is also associated with dental developmental disorders, malocclusion, and high caries index. There are limited data on the outcomes of dental treatments in maxillomandibular FD/MAS patients, because clinicians and researchers have limited access to patients, and there are concerns that dental surgery may activate quiescent jaw FD lesions to grow aggressively. This report highlights current perspectives on dental management issues associated with maxillomandibular FD within the context of MAS.

Disease severity and functional factors associated with walking performance in polyostotic fibrous dysplasia

The purpose of this study was to determine the association between measures of disease severity, impairment, and ambulation ability in persons with polyostotic fibrous dysplasia (PFD). A cross-sectional sample of 81 patients (ages 5-57) with polyostotic fibrous dysplasia was evaluated as part of an ongoing study. Subjects were scored on the Skeletal Disease Burden Score (SDBS), completed a 9-minute walk test (9MW), manual muscle testing (MMT), and measurements of range of motion (ROM). Correlations between continuous variables were calculated using the Pearson correlation coefficient and ordinal variables by Spearman correlation coefficient. It was found that subjects with more severe disease walked slower than those with less skeletal disease, with the exception of the youngest subjects. Walking velocity was faster in subjects with better hip strength and range of motion and slower in those with bilateral coxa vara. Those subjects with more severe disease had less range of motion, were weaker at the hips, and more likely to have leg length discrepancy. Skeletal disease severity was associated with hip weakness, leg length discrepancy, and loss of range of motion. In most cases, findings did not differ in the presence or absence of associated endocrinopathies. Skeletal disease severity, MMT and ROM each has an impact on walking efficiency in persons with PFD. These findings suggest that treatment focused on strategies to improve or, at least, maintain hip strength and range of motion, correct leg length discrepancies and hip malalignment may help preserve ambulation ability in persons with PFD and that treatment should begin at a young age.

Spinal polyostotic fibrous dysplasia in two adults: Does only biopsy unravel the mystery?

Polyostotic fibrous dysplasia is a rare non-inheritable genetic disease due to mutation in GNAS gene. Here we present two adults who were accidentally detected lytic lesions in spine and after extensive evaluation for malignancies; was diagnosed on biopsy. Current concept of the disease and management is discussed.

Sarcomatous transformation (Leiomyosarcoma) in polyostotic fibrous dysplagia

Malignant changes in polyostotic fibrous dysplasia are very rare. Most common malignancies reported are osteosarcoma and fibrosarcoma, chondrosarcoma and malignant fibrous histiocytoma. Here, we report a previously diagnosed case of fibrous dysplasia who has developed leiomyosarcoma; diagnosis of which was delayed for about one year despite repeated fine needle aspiration and open biopsy.

Intragenic suppression of a constitutively active allele of Gsα associated with McCune-Albright syndrome

McCune-Albright syndrome (MAS) is a human genetic disorder caused by a mutation that constitutively activates the G(s)α subunit by abolishing GTP hydrolysis. MAS patients suffer from a range of endocrinopathies as well as polyostotic fibrous dysplasia of bone. We previously identified an intragenic suppressor of the MAS mutation in a yeast system, which substituted two residues in the GTP-binding site of Gpa1: L318P and D319V to suppress the constitutive activity of an R297H mutation, corresponding to the human F222P, D223V, and R201H mutations respectively. To extend these studies, the human GNAS gene was subjected to site-directed mutagenesis. Constructs expressing the MAS mutation (R201H), the MAS mutation plus the mutations homologous to the yeast suppressors (R201H, F222P/D223V), or the yeast suppressor mutation alone (F222P/D223V) were transfected into HEK293 cells, and basal and receptor-stimulated cAMP levels were measured. Expression of R201H increased the basal cAMP levels and decreased the EC(50) for hormone-stimulated cAMP production. These effects were dependent on the amount of R201H protein expressed. R201H, F222P/D223V abolished the constitutive activity of the MAS mutation and caused responses to hormone that were not different from those measured in cells expressing WT G(s)α. Interestingly, F222P/D223V behaved similar to R201H in causing increases in basal cAMP production, thus demonstrating constitutive activity. Substitution of another acidic (E) or polar (N, T, and G) amino acid at position 223 caused no suppression of R201H activity, while substitution of a second nonpolar amino acid (A) at this position partially suppressed, and the larger polar I residue completely suppressed the effects of R201H.

Sinonasal disease in polyostotic fibrous dysplasia and McCune-Albright Syndrome

OBJECTIVES/HYPOTHESIS

To characterize the spectrum, symptoms, progression, and effects of endocrine dysfunction on sinonasal disease in polyostotic fibrous dysplasia (PFD) and McCune-Albright Syndrome (MAS).

STUDY DESIGN

Retrospective review.

METHODS

A prospectively followed cohort of subjects with PFD/MAS underwent a comprehensive evaluation that included otolaryngologic and endocrine evaluation, and imaging studies. Head and facial computed tomography scans were analyzed, and the degree of fibrous dysplasia (FD) was graded using a modified Lund-MacKay scale. Those followed for >4 years were analyzed for progression.

RESULTS

A total of 106 patients meeting inclusion criteria were identified with craniofacial FD. A majority (92%) demonstrated sinonasal involvement. There were significant positive correlations between the sinonasal FD scale score and chronic congestion, hyposmia, growth hormone excess, and hyperthyroidism (P < .05 for all). Significant correlations were not found for headache/facial pain or recurrent/chronic sinusitis. Thirty-one subjects met the criteria for longitudinal analysis (follow-up mean, 6.3 years; range, 4.4-9 years). Those who demonstrated disease progression were significantly younger than those who did not (mean age, 11 vs. 25 years). Progression after age of 13 years was uncommon (n = 3) and minimal. Concomitant endocrinopathy or bisphosphonate use did not have any significant effect on progression of disease.

CONCLUSIONS

Sinonasal involvement of fibrous dysplasia in PFD/MAS is common. Symptoms are usually few and mild, and disease progression occurs primarily in young subjects. Concomitant endocrinopathy is associated with disease severity, but not progression.

Craniofacial fibrous dysplasia

Despite recent advances in the understanding of the natural history and molecular abnormalities, many questions remain surrounding the progression and management of fibrous dysplasia (FD). In the absence of comorbidities, the expected behavior of craniofacial FD (CFD) is to be slow growing and without functional consequence. Understanding of the pathophysiologic mechanisms contributing to the various phenotypes of this condition, as well as the predictors of the different behaviors of FD lesions, must be improved. Long-term follow-up of patients with CFD is vital because spontaneous recovery is unlikely, and the course of disease can be unpredictable.

Skin lesions in hereditary endocrine tumor syndromes

OBJECTIVE

To review the main cutaneous manifestations of hereditary endocrine tumor syndromes and discuss currently known molecular mechanisms involved in their pathogenesis.

METHODS

On the basis of our collective experience and a comprehensive MEDLINE literature search of the English-language literature published between January 1957 and September 2010 using the search terms "skin," "cutaneous," "multiple endocrine neoplasia," "Carney complex," and "McCune-Albright syndrome," we reviewed the dermatologic findings in multiple endocrine neoplasia type 1 and type 2, Carney complex, and McCune-Albright syndrome.

RESULTS

Although the category of hereditary endocrine tumor syndromes consists of a broad spectrum of conditions, only the aforementioned few are prominently associated with cutaneous features. Because the cutaneous findings associated with these diseases are generally benign, they are often ignored or dismissed as ancillary findings in the context of severe systemic involvement. Accordingly, the pertinent literature is relatively scarce and often fails to provide a comprehensive insight about this issue. Nevertheless, timely recognition of such dermatologic manifestations may have a critical role in the early diagnosis and appropriate management of the related syndromes. Moreover, specific genotype-phenotype correlations may convey important prognostic implications.

CONCLUSION

Many physicians are unfamiliar with the cutaneous findings in the hereditary endocrine tumor syndromes described in this review. Nonetheless, knowledge of their existence can have a major role in establishing an early diagnosis of these syndromes and determining the patient's prognosis.

McCune-Albright syndrome revealed by hyperthyroidism at advanced age

We report a case of a 38-year-old woman admitted to our service for diagnosis of osteolytic lesions. She suffered from back, lumbar and costal pain at the time a hyperthyroidism, related to multinodular goiter, was diagnosed. The pain remained despite the cure of hyperthyroidism. Cutaneous examination revealed café au lait skin spots. Analysis of the phosphocalcic metabolism allowed the diagnosis of phosphate diabetes. X-ray showed lytic lesions involving the ribs with thinning of the cortex and vertebral fractures of the dorsal spine. The computed tomography revealed lytic lesions with a typical "ground glass" appearance involving the spine, ribs, sternum, iliac bones and sacrum. The presence of this clinical triad allowed the diagnosis of McCune-Albright syndrome (MAS). The treatment consisted in vitamin D supplementation, and high doses of both oral phosphate and calcitriol to treat the phosphate diabetes as well as cycles of intravenous pamidronate administration to relieve bone pain. We report an uncommon case of the diagnosis of MAS at an advanced age following hyperthyroidism. We believe that the disease was revealed by an increase in bone turnover due to hyperthyroidism.

Gs G protein-coupled receptor signaling in osteoblasts elicits age-dependent effects on bone formation

Age-dependent changes in skeletal growth are important for regulating skeletal expansion and determining peak bone mass. However, how G protein-coupled receptors (GPCRs) regulate these changes is poorly understood. Previously, we described a mouse model expressing Rs1, an engineered receptor with high basal G(s) activity. Rs1 expression in osteoblasts induced a dramatic age-dependent increase in trabecular bone with features resembling fibrous dysplasia. To further investigate how activation of the G(s)-GPCR pathway affects bone formation at different ages, we used the tetracycline-inducible system in the ColI(2.3)(+)/Rs1(+) mouse model to control the timing of Rs1 expression. We found that the Rs1 phenotype developed rapidly between postnatal days 4 and 6, that delayed Rs1 expression resulted in attenuation of the Rs1 phenotype, and that the Rs1-induced bone growth and deformities were markedly reversed when Rs1 expression was suppressed in adult mice. These findings suggest a distinct window of increased osteoblast responsiveness to G(s) signaling during the early postnatal period. In addition, adult bones encode information about their normal shape and structure independently from mechanisms regulating bone expansion. Finally, our model provides a powerful tool for investigating the effects of continuous G(s)-GPCR signaling on dynamic bone growth and remodeling.

Ligand-mediated activation of an engineered gs g protein-coupled receptor in osteoblasts increases trabecular bone formation

Age-dependent changes in skeletal growth play important roles in regulating skeletal expansion and in the course of many diseases affecting bone. How G protein-coupled receptor (GPCR) signaling affects these changes is poorly understood. Previously, we described a mouse model expressing Rs1, an engineered receptor with constitutive G(s) activity. Rs1 expression in osteoblasts from gestation induced a dramatic age-dependent increase in trabecular bone with features resembling fibrous dysplasia; however, these changes were greatly minimized if Rs1 expression was delayed until after puberty. To further investigate whether ligand-induced activation of the G(s)-GPCR pathway affects bone formation in adult mice, we activated Rs1 in adult mice with the synthetic ligand RS67333 delivered continuously via an osmotic pump or intermittently by daily injections. We found that osteoblasts from adult animals can be stimulated to form large amounts of bone, indicating that adult mice are sensitive to the dramatic bone- forming actions of G(s) signaling in osteoblasts. In addition, our results show that intermittent and continuous activation of Rs1 led to structurally similar but quantitatively different degrees of trabecular bone formation. These results indicate that activation of a G(s)-coupled receptor in osteoblasts of adult animals by either intermittent or continuous ligand administration can increase trabecular bone formation. In addition, osteoblasts located at the bone epiphyses may be more responsive to G(s) signaling than osteoblasts at the bone diaphysis. This model provides a powerful tool for investigating the effects of ligand-activated G(s)-GPCR signaling on dynamic bone growth and remodeling.

Recurring gnathodiaphyseal dysplasia in two Russian brothers

Two Russian brothers presented with recurring benign facial bone tumors and progressive limb bowing. The association of fibro-osseous jawbone lesions and long-bone bowing with cortical thickening suggested the diagnosis of gnathodiaphyseal dysplasia, in the absence of arguments in favor of fibrous dysplasia. Gnathodiaphyseal dysplasia is a rare autonomic dominant syndrome due to a mutation of the TMEM16E gene. The extreme and recurring phenotype of these two patients illustrates the variable expressivity of this disease. Differential diagnosis with other benign facial bone tumors is discussed.

[Fibrous dysplasia of bone in a young male]

Fibrous dysplasia of bone is a skeletal disease due to a specific mutation in the GNAS1 gene with a broad spectrum of clinical presentations ranging from isolated monostotic and polyostotic forms to associations with other extra-skeletal manifestations (McCune-Albright syndrome). The main complications are bone pain, deformities and fractures and sometimes cranial nerve compression and the development of bone sarcomas. Traumatologic surgery represents the principal approach in complicated lesions. Currently, the efficacy of pharmacological therapies is fairly limited. Cyclic administration of intravenous biphosphonates is the most effective approach to achieve symptomatic improvement and to lower the risk of fractures, although more evidence from well-designed randomized clinical trials evaluating the safety and efficacy of these treatments is still required. We present a case of polyostotic fibrous dysplasia of bone in a 19-year-old male.

Periostin, a novel marker of intramembranous ossification, is expressed in fibrous dysplasia and in c-Fos-overexpressing bone lesions

Fibrous dysplasia is a benign bone disease caused by a mutation in the gene for the stimulatory guanine nucleotide-binding protein Gs alpha, leading to high cyclic adenosine monophosphate levels. Histologically, fibrous dysplasia is characterized by the production of fibrous tissue accompanied by the deposition of ectopic type I collagen and other bone-associated extracellular matrix proteins, as well as by irregular woven intramembranous bone onto which type I collagen-containing Sharpey fibers are often attached. Fibrous dysplasia is also characterized by high expression of c-Fos/c-Jun, known targets for cyclic adenosine monophosphate signaling. In this study, we examined the expression of the bone-related extracellular matrix protein, periostin, and its known receptor, integrin alpha v beta 3 (CD51/61), in normal bones as well as in fibrous dysplasia. Immunohistochemistry and in situ hybridization studies revealed that periostin was expressed in the extracellular matrix during intramembranous but not endochondral ossification, as well as in the fibrous component of fibrous dysplasia; and all cells adjacent to periostin-positive regions expressed CD51/61. Importantly, periostin was abundantly localized to Sharpey fibers. To investigate the contribution of c-Fos, we examined transgenic mice overexpressing c-fos, which develop sclerotic lesions closely resembling those found in fibrous dysplasia. In all lesions, transformed osteoblasts expressed high levels of periostin, whereas normal osteoblasts did not. Our results show that periostin is a novel marker for intramembranous ossification, and is a good candidate as a diagnostic tool and/or a therapeutic target in fibrous dysplasia. Moreover, the Gs alpha-cyclic adenosine monophosphate-c-Fos pathway might represent one mechanism of periostin up-regulation in fibrous dysplasia, resulting in altered collagen fibrillogenesis characteristic of this disease.

The role of type 1 and type 2 5'-deiodinase in the pathophysiology of the 3,5,3'-triiodothyronine toxicosis of McCune-Albright syndrome

CONTEXT

McCune-Albright syndrome (MAS) is caused by mutations in GNAS (most often R201C or R201H) leading to constitutive cAMP signaling and multiple endocrine dysfunctions, including morphological and functional thyroid involvement.

OBJECTIVE

The objective of the study was to characterize the clinical and molecular features of the MAS-associated thyroid disease in a large cohort of patients.

DESIGN

This was a retrospective analysis.

SETTING

The study was conducted at the National Institutes of Health Clinical Center.

PATIENTS

The study included 100 consecutive MAS patients.

INTERVENTIONS

There were no interventions.

MAIN OUTCOME MEASURE

Functional and morphological evaluation of the thyroid was measured. Ex vivo experiments were performed on MAS thyroid samples to study the effects of the GNAS mutations on the 5'-deiodinases. Reconstitution experiments in HEK-293 cells were performed to study the effects of GNAS mutations on the type-2 5'-deiodinase.

RESULTS

Fifty-four patients had abnormal thyroid ultrasound findings. This group, compared with patients without abnormal findings, had higher T(3) to T(4) ratio, indicating an elevated 5'-deiodinase activity. Thyroid samples from MAS subjects, compared with normal tissue, showed a significant increase in both type 1 (D1) and type 2 (D2) 5'-deiodinase activity (D1 control 5.9 +/- 4.5 vs. MAS 41.7 +/- 26.8 fmol/min.mg, P < 0.001; D2 control 28.3 +/- 13.8 vs. MAS 153.1 +/- 43.7 fmol/min.mg, P < 0.001). Compared with cells transfected with the wild-type R201 allele, the basal transcriptional activity of the D2 promoter was significantly increased in both mutants (C and H) (R 10733 +/- 2855, vs. C 18548 +/- 4514, vs. H 19032 +/- 4410 RLU +/- SD, P < 0.001).

CONCLUSION

Thyroid pathology is a common occurrence in MAS. Consistent with the molecular etiology of the disease, the shift in T(3) to T(4) ratio is at least in part secondary to a cAMP-mediated intrathyroidal activation of D2 and to elevated D1 activity.

McCune-Albright syndrome

McCune-Albright syndrome (MAS) is classically defined by the clinical triad of fibrous dysplasia of bone (FD), café-au-lait skin spots, and precocious puberty (PP). It is a rare disease with estimated prevalence between 1/100,000 and 1/1,000,000. FD can involve a single or multiple skeletal sites and presents with a limp and/or pain, and, occasionally, a pathologic fracture. Scoliosis is common and may be progressive. In addition to PP (vaginal bleeding or spotting and development of breast tissue in girls, testicular and penile enlargement and precocious sexual behavior in boys), other hyperfunctioning endocrinopathies may be involved including hyperthyroidism, growth hormone excess, Cushing syndrome, and renal phosphate wasting. Café-au-lait spots usually appear in the neonatal period, but it is most often PP or FD that brings the child to medical attention. Renal involvement is seen in approximately 50% of the patients with MAS. The disease results from somatic mutations of the GNAS gene, specifically mutations in the cAMP regulating protein, G_s alpha. The extent of the disease is determined by the proliferation, migration and survival of the cell in which the mutation spontaneously occurs during embryonic development. Diagnosis of MAS is usually established on clinical grounds. Plain radiographs are often sufficient to make the diagnosis of FD and biopsy of FD lesions can confirm the diagnosis. The evaluation of patients with MAS should be guided by knowledge of the spectrum of tissues that may be involved, with specific testing for each. Genetic testing is possible, but is not routinely available. Genetic counseling, however, should be offered. Differential diagnoses include neurofibromatosis, osteofibrous dysplasia, non-ossifying fibromas, idiopathic central precocious puberty, and ovarian neoplasm. Treatment is dictated by the tissues affected, and the extent to which they are affected. Generally, some form of surgical intervention is recommended. Bisphosphonates are frequently used in the treatment of FD. Strengthening exercises are recommended to help maintaining the musculature around the FD bone and minimize the risk for fracture. Treatment of all endocrinopathies is required. Malignancies associated with MAS are distinctly rare occurrences. Malignant transformation of FD lesions occurs in probably less than 1% of the cases of MAS.