Skeletal fluorosis secondary to methoxyflurane use for chronic pain

Skeletal fluorosis is rare and occurs secondary to chronic high amounts of fluoride consumption, manifesting as diffuse osteosclerosis, skeletal pain, connective tissue calcification, and increased fracture risk. Methoxyflurane is a volatile, fluorinated hydrocarbon-inhaled analgesic, and the maximum recommended dose is 15 mL (99.9 % w/w) per wk. A rodent study found increased skeletal fluoride after methoxyflurane exposure. However, skeletal fluorosis secondary to methoxyflurane use in humans has rarely been reported. We present the case of a 47-yr-old female with diffuse osteosclerosis secondary to fluorosis from methoxyflurane use for chronic pain, presenting with 3 yr of generalized bony pain and multiple fragility fractures. Lumbar spine BMD was elevated. CT and radiographs demonstrated new-onset marked diffuse osteosclerosis, with calcification of interosseous membranes and ligaments, and a bone scan demonstrated a grossly increased uptake throughout the skeleton. Biochemistry revealed an elevated alkaline phosphatase and bone turnover markers, mild secondary hyperparathyroidism with vitamin D deficiency, and mild renal impairment. Zoledronic acid, prescribed for presumed Paget's disease, severely exacerbated bony pain. Urinary fluoride was elevated (7.3 mg/L; reference range < 3.0 mg/L) and the patient revealed using methoxyflurane 9 mL per wk for 8 yr for chronic pain. A decalcified bone biopsy revealed haphazardly arranged cement lines and osteocytes lacunae and canaliculi, which was consistent with an osteosclerotic process. Focal subtle basophilic stippling around osteocyte lacunae was suggestive of fluorosis. Although fluorosis is not a histological diagnosis, the presence of compatible histology features was supportive of the diagnosis in this case with clinical-radiological-pathological correlation. Skeletal fluorosis should be considered as a cause of acquired diffuse osteosclerosis. Methoxyflurane should not be recommended for chronic pain. The risk of repeated low-dose exposure to fluoride from methoxyflurane use as analgesia may be greater than expected, and the maximum recommended dose for methoxyflurane may require re-evaluation to minimize skeletal complications.

Abbreviated abstract

Skeletal fluorosis is rare and occurs secondary to chronic high amounts of fluoride consumption, manifesting as diffuse osteosclerosis, skeletal pain, connective tissue calcification, and increased fracture risk. We present the case of a 47-yr-old female with skeletal fluorosis secondary to long-term methoxyflurane for chronic pain. The risk of repeated low-dose exposure to fluoride from methoxyflurane use for analgesia may be greater than expected, and the maximum recommended dose for methoxyflurane may require re-evaluation to minimize skeletal complications.

A 48-Year-Old Man With a Hip Fracture and Skin Rash: A Case Report

Background/Objective

Patients with systemic mastocytosis are at high risk of developing osteoporosis and fractures. Herein, we report a case of hip fragility fracture in a patient with indolent systemic mastocytosis and normal bone density.

Case Report

A 48-year-old man experienced a left femoral neck fracture after a fall. After a dose of oxycodone/hydromorphone postoperatively, he developed an anaphylactic reaction. Previously, he experienced a few other episodes of flushing, dizziness, and syncope precipitated by stress and alcohol. His examination was notable for pink and brown macules on his chest, back, arms, and legs. His laboratory test revealed a markedly elevated tryptase level of 171 ng/mL (<11 ng/mL). Treatment including cetirizine, montelukast, and ranitidine controlled his symptoms. His bone density test result was normal. Ten months after hip surgery, his c-terminal telopeptide of collagen type 1 and bone-specific alkaline phosphatase levels significantly increased. The bone scan demonstrated diffusely increased radiotracer uptake throughout the osseous structures. Given high bone turnover and the prior hip fracture, he received zoledronic acid yearly for 3 years, and no further fractures have occurred.

Discussion

The case is unusual as the fracture occurred despite normal bone density and significant osteosclerosis, which was previously considered protective against fractures. Additionally, rather than the spine, the fracture occurred in the hip, which is an uncommon site for mastocytosis-induced fractures.

Conclusion

Mastocytosis is a rare cause of osteoporosis, and it is important to keep this condition in the differential diagnosis of osteoporosis, particularly when the fracture presentation is atypical.

Hdac1 and Hdac2 positively regulate Notch1 gain-of-function pathogenic signaling in committed osteoblasts of male mice

BACKGROUND

Skeletal development requires precise extrinsic and intrinsic signals to regulate processes that form and maintain bone and cartilage. Notch1 is a highly conserved signaling receptor that regulates cell fate decisions by controlling the duration of transcriptional bursts. Epigenetic molecular events reversibly modify DNA and histone tails by influencing the spatial organization of chromatin and can fine-tune the outcome of a Notch1 transcriptional response. Histone deacetylase 1 and 2 (HDAC1 and HDAC2) are chromatin modifying enzymes that mediate osteoblast differentiation. While an HDAC1-Notch interaction has been studied in vitro and in Drosophila, its role in mammalian skeletal development and disorders is unclear. Osteosclerosis is a bone disorder with an abnormal increase in the number of osteoblasts and excessive bone formation.

METHODS

Here, we tested whether Hdac1/2 contribute to the pathogenesis of osteosclerosis in a murine model of the disease owing to conditionally cre-activated expression of the Notch1 intracellular domain in immature osteoblasts.

RESULTS

Importantly, selective homozygous deletions of Hdac1/2 in osteoblasts partially alleviate osteosclerotic phenotypes (Col2.3kb-Cre; TGRosaN1ICD/+ ; Hdac1flox/flox ; Hdac2flox/flox ) with a 40% decrease in bone volume and a 22% decrease in trabecular thickness in 4 weeks old when compared to male mice with heterozygous deletions of Hdac1/2 (Col2.3 kb-Cre; TGRosaN1ICD/+ ; Hdac1flox/+ ; Hdac2flox/+ ). Osteoblast-specific deletion of Hdac1/2 in male and female mice results in no overt bone phenotype in the absence of the Notch1 gain-of-function (GOF) allele.

CONCLUSIONS

These results provide evidence that Hdac1/2 contribute to Notch1 pathogenic signaling in the mammalian skeleton. Our study on epigenetic regulation of Notch1 GOF-induced osteosclerosis may facilitate further mechanistic studies of skeletal birth defects caused by Notch-related GOF mutations in human patients, such as Adams-Oliver disease, congenital heart disease, and lateral meningocele syndrome.

Mutations of family with sequence similarity 20-member C gene causing lethal and nonlethal Raine syndrome causes hypophosphatemia rickets

Family with sequence similarity 20-member C (FAM20C) is a kinase specific to most of the secreted phosphoproteome. FAM20C has been identified as the causative gene of Raine syndrome, initially characterized by lethal osteosclerosis bone dysplasia. However, since the identification of the cases of nonlethal Raine syndrome characterized by hypophosphatemia rickets, the previous definition of Raine syndrome has become debatable and raised a question about the role of mutations of FAM20C in controversial skeletal manifestation in the two forms of the disease. In this study, we aimed to investigate the influence of FAM20C mutations on skeletogenesis. We developed transgenic mice expressing Fam20c mutations mimicking those associated with human lethal and nonlethal Raine syndrome. The results revealed that transgenic mice expressing the mutant Fam20c found in the lethal (KO;G374R) and nonlethal (KO;D446N) Raine syndrome exhibited osteomalacia without osteosclerotic features. Additionally, both mutants significantly increased the expression of the Fgf23, indicating that Fam20c deficiency in skeletal compartments causes hypophosphatemia rickets. Furthermore, as FAM20C kinase activity catalyzes the phosphorylation of secreted proteomes other than those in the skeletal system, global FAM20C deficiency may trigger alterations in other systems resulting in osteosclerosis secondary to hypophosphatemia rickets. Together, the findings of this study suggest that FAM20C deficiency primarily causes hypophosphatemia rickets or osteomalacia; however, the heterogeneous skeletal manifestation in Raine syndrome was not determined solely by specific mutations of FAM20C. The findings also implicated that rickets or osteomalacia caused by FAM20C deficiency would deteriorate into osteosclerosis by the defects from other systems or environmental impacts.

Increased local bone turnover in patients with chronic periprosthetic joint infection

Aims

The management of periprosthetic joint infection (PJI) remains a major challenge in orthopaedic surgery. In this study, we aimed to characterize the local bone microstructure and metabolism in a clinical cohort of patients with chronic PJI.

Methods

Periprosthetic femoral trabecular bone specimens were obtained from patients suffering from chronic PJI of the hip and knee (n = 20). Microbiological analysis was performed on preoperative joint aspirates and tissue specimens obtained during revision surgery. Microstructural and cellular bone parameters were analyzed in bone specimens by histomorphometry on undecalcified sections complemented by tartrate-resistant acid phosphatase immunohistochemistry. Data were compared with control specimens obtained during primary arthroplasty (n = 20) and aseptic revision (n = 20).

Results

PJI specimens exhibited a higher bone volume, thickened trabeculae, and increased osteoid parameters compared to both control groups, suggesting an accelerated bone turnover with sclerotic microstructure. On the cellular level, osteoblast and osteoclast parameters were markedly increased in the PJI cohort. Furthermore, a positive association between serum (CRP) but not synovial (white blood cell (WBC) count) inflammatory markers and osteoclast indices could be detected. Comparison between different pathogens revealed increased osteoclastic bone resorption parameters without a concomitant increase in osteoblasts in bone specimens from patients with Staphylococcus aureus infection, compared to those with detection of Staphylococcus epidermidis and Cutibacterium spp.

Conclusion

This study provides insights into the local bone metabolism in chronic PJI, demonstrating osteosclerosis with high bone turnover. The fact that Staphylococcus aureus was associated with distinctly increased osteoclast indices strongly suggests early surgical treatment to prevent periprosthetic bone alterations.

Systemic osteosclerosis associated with primary bone marrow B-cell lymphoma

Systemic osteosclerosis is a rare complication of hematological malignancies. Primary myelofibrosis and acute megakaryocytic leukemia are known as underlying diseases; however, lymphoid tumors have rarely been reported. Here we describe a case of a 50-year-old man with severe systemic osteosclerosis associated with primary bone marrow B-cell lymphoma. Analysis of bone metabolic markers revealed a high turnover of bone metabolism and an increase in serum osteoprotegerin levels. These results suggest the involvement of osteoprotegerin in the pathogenesis of osteosclerosis associated with hematological malignancies.

Chronic osteomyelitis mimicking a temporomandibular disorder: a case report of two cases

Chronic osteomyelitis of the jaw is rare in the healthy populations of developed countries and presents with diagnostic and therapeutic challenges. Clinical presentation: Patient 1 presented with a dull, occasionally throbbing pain in the left mandible of 1.5 years duration. There was associated trismus which alternated between improving and worsening. The patient had features mimicking a variant of temporomandibular disorder (TMD). She was misdiagnosed and treated for myogenous TMD without symptom relief. Patient 2 presented with intermittent dull pain with mastication and facial swelling over the right mandible for 1 year. She was treated by the referring dental practitioner for myogenous TMD without symptom relief. Clinical and radiologic findings confirmed a diagnosis of chronic sclerosing osteomyelitis in both cases, and conservative treatment, including antibiotics, relieved the pain with no signs of recurrence. Conclusion: The importance of including chronic osteomyelitis in the differential diagnosis of idiopathic orofacial pain disorders is emphasized. If the management of myogenous TMD is unsuccessful, there is a possibility of a misdiagnosis, and a differential diagnosis, including chronic osteomyelitis, needs to be reconsidered.

Compound heterozygous FAM20C gene variants in a patient with severe Raine syndrome: a case report

Raine syndrome is a congenital disorder caused by biallelic mutations in the FAM20C gene. While most diagnosed cases of the syndrome are lethal in the first few months of life, there are also reports of non-lethal cases with Raine syndrome. The characteristic of this syndrome is typical facial dysmorphism and generalized osteosclerosis, as well as possible intracranial calcification, hearing loss, and seizures. We report a case of a 4-day-old patient at the time of examination, born with a distinct facial dysmorphism, short neck, narrow chest, and curved tibia. The parents, affirmative gypsy and non-consanguineous, had a previous male child born with the same phenotype who died at 4 months old. The computed tomography scan revealed choanal atresia, while transfontanelar ultrasound showed hypoplasia of the frontal and temporal lobes, corpus callosum dysgenesis, and multiple areas of intracranial hyperechogenicity. The chest X-Ray revealed generalized increased bone density. A skeletal disorders gene panel was performed which identified two variants in the FAM20C gene: a pathogenic variant c.1291C>T (p.Gln431*) and a likely pathogenic variant (c.1135G>A) (p.Gly379Arg), confirming the clinical diagnosis. The parents were also tested, and each was found to carry one of the variants. The particularity of this case is the severe phenotype in a compound heterozygous case that consists of FAM20C c.1291C>T (p.Gln431*) variant that has recently been reported in the literature. Also, our case is one of the few compound-heterozygous mutations in the FAM20C gene that has been described in a non-consanguineous marriage.

Platelets and osteoblasts: secretome connections

Megakaryocyte hyperplasia associated with myeloproliferative neoplasms commonly leads to abnormal bone tissue deposition in the bone marrow, known as osteosclerosis. In this study, we aimed to synthesize the known proteomics literature describing factors released by megakaryocytes and platelets and to examine if any of the secreted factors have a known ability to stimulate the bone-forming cells, osteoblasts. Using a systematic search of Medline, we identified 77 articles reporting on factors secreted by platelets and megakaryocytes. After a full-text screening and analysis of the studies, we selected seven papers that reported proteomics data for factors secreted by platelets from healthy individuals. From 60 proteins reported in at least two studies, we focused on 23 that contained a putative signal peptide, which we searched for a potential osteoblast-stimulatory function. From nine proteins with a positive effect on osteoblast formation and function, two extracellular matrix (ECM) proteins, secreted protein acidic and rich in cysteine (SPARC) and tissue inhibitor of metalloproteinase-1 (TIMP1), and three cellular proteins with known extracellular function, the 70-kDa heat shock protein (HSP70), thymosin-β4 (TB4), and super dismutase (SOD), were identified as hypothetical candidate molecules to be examined as potential mediators in mouse models of osteomyelofibrosis. Thus, careful analysis of prior literature can be beneficial in assisting the planning of future experimental studies.

Pseudo-pheochromocytoma due to obstructive sleep apnea: a case report

SUMMARY

Obstructive sleep apnea (OSA) is a condition of intermittent nocturnal upper airway obstruction. OSA increases sympathetic drive which may result in clinical and biochemical features suggestive of pheochromocytoma. We present the case of a 65-year-old male with a 2.9-cm left adrenal incidentaloma on CT, hypertension, symptoms of headache, anxiety and diaphoresis, and persistently elevated 24-h urine norepinephrine (initially 818 nmol/day (89-470)) and normetanephrine (initially 11.2 µmol/day (0.6-2.7)). He was started on prazosin and underwent left adrenalectomy. Pathology revealed an adrenal corticoadenoma with no evidence of pheochromocytoma. Over the next 2 years, urine norepinephrine and normetanephrine remained significantly elevated with no MIBG avid disease. Years later, he was diagnosed with severe OSA and treated with continuous positive airway pressure. Urine testing done once OSA was well controlled revealed complete normalization of urine norepinephrine and normetanephrine with substantial symptom improvement. It was concluded that the patient never had a pheochromocytoma but rather an adrenal adenoma with biochemistry and symptoms suggestive of pheochromocytoma due to untreated severe OSA. Pseudo-pheochromocytoma is a rare presentation of OSA and should be considered on the differential of elevated urine catecholamines and metanephrines in the right clinical setting.

LEARNING POINTS

Obstructive sleep apnea (OSA) is a common condition among adults. OSA may rarely present as pseudo-pheochromocytoma with symptoms of pallor, palpitations, perspiration, headache, or anxiety. OSA should be considered on the differential of elevated urine catecholamines and metanephrines, especially in patients with negative metaiodobenzylguanidine (MIBG) scan results.

Multivariable logistic regression models of X-ray thoracic spinous process osseous changes findings and body measurement factors associated with defined over-riding of the dorsal spinous in riding horses

Thoracic spinous process osseous changes in horses occur due to riding-induced back compression. This study aimed to evaluate the relationship between the findings of thoracic spinous process osseous changes on radiographic imaging and conformation based on the difference in over-riding of the dorsal spinous processes in racing horses. This study included 55 sports horses. The hardness of the back muscles (the multifidus, longissimi, and latissimi collectively) was measured, and the horses were divided into two groups: low muscle hardness (n=16) and high muscle hardness (n=39). We confirmed the effectiveness of a muscle hardness tester in measuring the hardness of the back muscles. It was revealed that horses with a long length from the saddle (13th thoracic vertebra) to the sacral lumbar joint (5th lumbar vertebra) had higher muscle hardness. Additionally, horses with high muscle hardness demonstrated spinous process osteosclerosis.

Megakaryocyte-driven changes in bone health: lessons from mouse models of myelofibrosis and related disorders

Over the years, numerous studies demonstrated reciprocal communications between processes of bone marrow hematopoiesis and bone remodeling. Megakaryocytes, rare bone marrow cells responsible for platelet production, were demonstrated to be involved in bone homeostasis. Myelofibrosis, characterized by an increase in pleomorphic megakaryocytes in the bone marrow, commonly leads to the development of osteosclerosis. In vivo, an increase in megakaryocyte number was shown to result in osteosclerosis in GATA-1^low, NF-E2^-/-, TPO^high, Mpll^f/f;PF4cre, Lnk^-/-, Mpig6b^-/-, Mpig6b^fl/fl;Gp1ba-Cr^+/KI, Pt-vWD mouse models. In vitro, megakaryocytes stimulate osteoblast proliferation and have variable effects on osteoclast proliferation and activity through soluble factors and direct cell-cell communications. Intriguingly, new studies revealed that the ability of megakaryocytes to communicate with bone cells is affected by the age and sex of animals. This mini-review summarises changes seen in bone architecture and bone cell function in mouse models with an elevated number of megakaryocytes and the effects megakaryocytes have on osteoblasts and osteoclasts in vitro, and discusses potential molecular players that can mediate these effects.

Bone metastases with post-treatment intralesional fatty content of the spine: imaging features from T1-weighted imaging with CT finding correlations

BACKGROUND

Despite post-treatment intralesional fatty content (PIFAT) in bone metastases indicating a healing processes after treatment, the imaging features of PIFAT have not been studied in detail.

PURPOSE

To analyze imaging features from T1-weighted (T1W) imaging with computed tomography (CT) finding correlations in bone metastases with PIFAT of the spine.

MATERIAL AND METHODS

A total of 29 bone metastases with PIFAT were analyzed with T1W and CT images before and after treatment. On T1W imaging after treatment, the lesions were categorized into three types according to fat distribution patterns. CT attenuation changes after treatment were also evaluated. According to the MD Anderson (MDA) criteria, response types for all lesions were obtained on magnetic resonance (MR) and CT images.

RESULTS

The types from T1W imaging in bone metastases with PIFAT were as follows: 14 with a return to totally normal marrow signal intensity within the lesion; 13 with an inhomogeneous patchy pattern in the lesion; and two with a peripheral halo of fatty marrow or peripheral fat signal intensity foci in the lesion. Among bone metastases with PIFAT, 93.1% showed osteosclerotic changes in this study. According to the MDA criteria, the concordance between the response types of the MR and CT images was 57.2%.

CONCLUSION

Knowledge of imaging features from T1W imaging with CT correlation in bone metastases with PIFAT is important for the accurate interpretation of post-treatment MR and CT studies. Both MR and CT images have a complementary value regarding the post-treatment evaluation of bone metastases with PIFAT.

Hypersalinity drives convergent bone mass increases in Miocene marine mammals from the Paratethys

Pachyosteosclerosis-a condition that creates dense, bulky bones-often characterizes the early evolution of secondarily aquatic tetrapods like whales and dolphins^1-3 but then usually fades away as swimming efficiency increases.⁴ Here, we document a remarkable reversal of this pattern, namely the convergent re-emergence of bone densification in Miocene seals, dolphins, and whales from the epicontinental Paratethys Sea of eastern Europe and central Asia. This phenomenon was driven by imbalanced remodeling and inhibited resorption of primary trabeculae and coincided with hypersaline conditions-the Badenian salinity crisis-that affected the Central Paratethys between 13.8 and 13.4 Ma.⁵ Dense bones acting as ballast would have facilitated efficient swimming in the denser and more buoyant water and hence were likely adaptive in this setting. From the Central Paratethys, pachyosteosclerosis subsequently spread eastward, where it became a defining feature of the endemic late Miocene whale assemblage.^6,7.

Osteoid osteoma of the rib with strong F-18 fluoro-deoxyglucose uptake mimicking osteoblastoma: a case report with literature review

Osteoid osteoma is a benign osteoblastic bone lesion, characterized by nocturnal pain alleviated by salicylates or nonsteroidal anti-inflammatory drugs. This tumor distinctly affects the long bones, typically the femur or tibia and is rarely located in the ribs. Usually, this tumor is usually diagnosed by computed tomography or magnetic resonance imaging, but F-18 fluoro-deoxyglucose positron emission tomographic (FDG-PET)/computed tomography is usually negative and is not used for diagnosis. We recently encountered a case of an osteoid osteoma located in the rib of 44-year-old Asian male with strong FDG uptake as high as 12.0 at the maximum standardized uptake value at FDG-PET/computed tomography. His computed tomography and magnetic resonance imaging showed osteosclerosis, bone marrow edema, and edema of surrounding tissues not only in the bone with nidus but also in the adjacent bone, and pathological findings showed strong infiltration munched radiology. Strong FDG uptake mimicking osteoblastoma. Osteoid osteoma with strong FDG uptake suggested a strong inflammatory response.

Resolution of sclerotic lesions of dysosteosclerosis due to biallelic SLC29A3 variant in a Turkish girl

Dysosteosclerosis is a group of sclerosing bone dysplasia characterized by short stature, increased bone fragility, osteosclerosis, and platyspondyly. It is a genetically heterogeneous disorder caused by biallelic mutations in the SLC29A3, TNFRSF11A, TCIRG1, and CSF1R genes. To date, four dysosteosclerosis patients with SLC29A3 mutations have been reported. Here, we report biallelic SLC29A3 (c.303_320dupCTACTTTGAGAGCTACCT) variant in a three-year-old girl. She had large anterior fontanelle, fracture history, short stature, camptodactyly, elbow contracture, and melanocytic nevus. Initial skeletal radiographs revealed platyspondyly, dense vertebral endplates (sandwich appearance of the vertebral bodies), diffuse sclerosis of the peripheral side of the pelvic bones, sclerosis of metaphysis and diaphysis of the long bones, metaphyseal widening, and diaphyseal cortical thickening. Mild sclerosis was also present in the skull base, maxilla, rib, scapula, and phalanges. Notably, we observed that sandwich vertebrae appearance significantly resolved and sclerosis of ribs, scapula, pelvis, and long bone metaphysis regressed over a 2.5-year period. However, platyspondyly, metaphyseal widening, and diaphyseal cortical thickening persisted. In conclusion, this study demonstrates spontaneous resolution of osteosclerosis, which was not described previously in patients with dysosteosclerosis.

The Skinner Burial of Ontario, Canada, and the Question of Paget's Disease in the Americas

PURPOSE

To examine a possible case of Paget's disease of bone (PDB) in an Indigenous pre-contact male from Canada, individual D of the Skinner site in Ontario.

METHODS

Radiographs, CT scan and histological analysis.

RESULTS

The histological analysis revealed the mosaic pattern that characterizes PDB. CT scans show advanced sclerosis of the cranium and a diminished diplӧe with osteolytic lesions.

CONCLUSIONS

The pathological features that have been identified are collectively characteristic of PDB.

SIGNIFICANCE

The Skinner case advances our understanding of the global history and distribution of PDB.

LIMITATIONS OF STUDY

Only two New World cases have been identified and neither has been studied in sufficient detail.

SUGGESTIONS FOR FUTURE RESEARCH

The older individuals in precolonial New World skeletal series should be given CT scans, which are non-intrusive, to be followed by histological and genetic analyses when indicated.

Improvement in the Symptoms and VEGF Levels after Resection of an Extrame Dullary Spinal Tumor and Additional Chemotherapy in a Patient with Multiple Myeloma Complicated with POEMS Syndrome

We herein report a case of multiple myeloma and polyneuropathy, organomegaly, endocrinopathy, myeloma protein, and skin changes (POEMS) syndrome. The patient experienced exacerbated gait disturbance due to weakness and numbness in the lower limbs. Thoracic magnetic resonance imaging revealed an extramedullary tumor with spinal compression that required surgical resection. Plasmacytoma was diagnosed based on a biopsy. Radiation, betamethasone, and chemotherapy were therefore administered. Surgical removal of extramedullary tumors improved his symptoms, motor conduction velocity, and amplitude of the muscle action potential in the peroneal and tibial nerves, as shown by the nerve conduction study. Surgery also decreased the serum vascular endothelial growth factor levels. The patient required additional chemotherapy due to multiple myeloma and showed better outcomes nine months after discharge. The benefits of some treatments remain controversial due to the small number of patients. However, our findings reveal that an early diagnosis and comprehensive treatment may result in better outcomes in such patients.

Skeletal Fluorosis: An Unusual Manifestation of Computer Cleaner Inhalant Abuse

Skeletal fluorosis is a metabolic bone disease caused by accumulation of fluoride and is generally associated with chronic exposure to fluoride-contaminated groundwater, a phenomenon endemic to developing countries. Whereas elevated water fluoride concentrations do not constitute a public health issue in the United States, emergence of skeletal fluorosis as a sequela of chronic recreational exposures has been described. In this case report, our 33-year-old male patient with a history of major depressive disorder and substance abuse was hospitalized for hyperkalemia and acute kidney injury discovered on routine bloodwork due to concomitant nonsteroidal anti-inflammatory drugs (NSAID) and antihypertensive use. Upon hospital admission, he was found to be anemic with a significantly elevated alkaline phosphatase. Given a history of low back pain in the setting of these laboratory abnormalities, lower spine and pelvic imaging revealed diffusely increased bone density and sclerosis. Hematologic evaluation ensued to include a peripheral smear and bone marrow biopsy. Given the patient’s history of computer cleaner inhalant abuse, serum and urinary fluoride levels were obtained. Serum fluoride returned within normal limits though urinary fluoride was increased. Bone marrow histopathology revealed prominent diffuse sclerosis which in conjunction with urinary fluoride levels and computer cleaner inhalant abuse history supported the diagnosis of skeletal fluorosis. Skeletal fluorosis in the United States is rare and presents with non-specific findings requiring a high index of suspicion based on a detailed patient history for expedient diagnosis.

An Activating Variant in CTNNB1 is Associated with a Sclerosing Bone Dysplasia and Adrenocortical Neoplasia

CONTEXT

The WNT/β-catenin pathway is central to the pathogenesis of various human diseases including those affecting bone development and tumor progression.

OBJECTIVE

To evaluate the role of a gain-of-function variant in CTNNB1 in a child with a sclerosing bone dysplasia and an adrenocortical adenoma.

DESIGN

Whole exome sequencing with corroborative biochemical analyses.

PATIENTS

We recruited a child with a sclerosing bone dysplasia and an adrenocortical adenoma together with her unaffected parents.

INTERVENTION

Whole exome sequencing and performance of immunoblotting and luciferase-based assays to assess the cellular consequences of a de novo variant in CTNNB1.

MAIN OUTCOME MEASURE(S)/RESULT

A de novo variant in CTNNB1 (c.131C>T; p.[Pro44Leu]) was identified in a patient with a sclerosing bone dysplasia and an adrenocortical adenoma. A luciferase-based transcriptional assay of WNT signaling activity verified that the activity of β-catenin was increased in the cells transfected with a CTNNB1p.Pro44Leu construct (P = 4.00 × 10-5). The β-catenin p.Pro44Leu variant was also associated with a decrease in phosphorylation at Ser45 and Ser33/Ser37/Thr41 in comparison to a wild-type (WT) CTNNB1 construct (P = 2.16 × 10-3, P = 9.34 × 10-8 respectively).

CONCLUSION

Increased β-catenin activity associated with a de novo gain-of-function CTNNB1 variant is associated with osteosclerotic phenotype and adrenocortical neoplasia.

A novel FAM20C mutation causes a rare form of neonatal lethal Raine syndrome

Raine syndrome is a rare, autosomal recessive, osteosclerotic bone dysplasia due to pathogenic variants in FAM20C. The clinical phenotype is characterized by generalized osteosclerosis affecting all bones, cerebral calcifications, and craniofacial dysmorphism. Most cases present during the neonatal period with early lethality due to pulmonary hypoplasia and respiratory compromise while only few affected individuals have been reported to survive into adulthood. FAM20C is a ubiquitously expressed protein kinase that contains five functional domains including a catalytic domain, a binding pocket for FAM20A and three distinct N-glycosylation sites. We report a newborn infant with a history of prenatal onset fractures, generalized osteosclerosis, and craniofacial dysmorphism and early lethality. The clinical presentation was highly suggestive of Raine syndrome. A homozygous, novel missense variant in exon 5 of FAM20C (c.1007T>G; p.Met336Arg) was identified by targeted Sanger sequencing. Following in silico analysis and mapping of the variant on a three-dimensional (3D) model of FAM20C it is predicted to be deleterious and to affect N-glycosylation, protein folding, and subsequent secretion of FAM20C. In addition, we reviewed all published FAM20C mutations and observed that most pathogenic variants affect functional regions within the protein establishing evidence for an emerging genotype-phenotype correlation.

Pycnodysostosis: Natural history and management guidelines from 27 French cases and a literature review

Pycnodysostosis is a lysosomal autosomal recessive skeletal dysplasia characterized by osteosclerosis, short stature, acro-osteolysis, facial features and an increased risk of fractures. The clinical heterogeneity of the disease and its rarity make it difficult to provide patients an accurate prognosis, as well as appropriate care and follow-up. French physicians from the OSCAR network have been asked to fill out questionnaires collecting molecular and clinical data for 27 patients issued from 17 unrelated families. All patients showed short stature (mean = -3.5 SD) which was more severe in females (P = .006). The mean fracture rate was moderate (0.21 per year), with four fractures in total average. About 75% underwent at least one surgery, with an average number of 2.1 interventions per patient. About 50% required non-invasive assisted ventilation due to sleep apnea (67%). About 29% showed psychomotor difficulties and 33% needed a school assistant or adapted schooling. No patient had any psychological evaluation or follow-up. Molecular data were available for 14 families. Growth hormone administration was efficient on linear growth in 40% of cases. We propose several axis of management, such as systematic cerebral MRI for Chiari malformation screening at diagnosis and regular psychological follow-up.

Bi-allelic CSF1R Mutations Cause Skeletal Dysplasia of Dysosteosclerosis-Pyle Disease Spectrum and Degenerative Encephalopathy with Brain Malformation

Colony stimulating factor 1 receptor (CSF1R) plays key roles in regulating development and function of the monocyte/macrophage lineage, including microglia and osteoclasts. Mono-allelic mutations of CSF1R are known to cause hereditary diffuse leukoencephalopathy with spheroids (HDLS), an adult-onset progressive neurodegenerative disorder. Here, we report seven affected individuals from three unrelated families who had bi-allelic CSF1R mutations. In addition to early-onset HDLS-like neurological disorders, they had brain malformations and skeletal dysplasia compatible to dysosteosclerosis (DOS) or Pyle disease. We identified five CSF1R mutations that were homozygous or compound heterozygous in these affected individuals. Two of them were deep intronic mutations resulting in abnormal inclusion of intron sequences in the mRNA. Compared with Csf1r-null mice, the skeletal and neural phenotypes of the affected individuals appeared milder and variable, suggesting that at least one of the mutations in each affected individual is hypomorphic. Our results characterized a unique human skeletal phenotype caused by CSF1R deficiency and implied that bi-allelic CSF1R mutations cause a spectrum of neurological and skeletal disorders, probably depending on the residual CSF1R function.

Microstructure of Vertebrae, Ribs, and Gastralia of Triassic Sauropterygians-New Insights into the Microanatomical Processes Involved in Aquatic Adaptations of Marine Reptiles

Isolated ribs and vertebrae of Middle Triassic sauropterygians are studied. The vertebrae have a well-defined large cavity in their centra, which is a unique feature and is without any modern analogue. The articular facets of vertebrae are made of endochondral bone including calcified as well as uncalcified cartilage. Vertebrae are pachyosteosclerotic in the pachypleurosaurs Neusticosaurus and Serpianosaurus from the Alpine Triassic, and osteosclerotic in the placodont, in the medium-sized Nothosaurus marchicus, and in the pachypleurosaur Anarosaurus. In large Nothosaurus specimens, the vertebrae are cavernous. The ribs of all sampled specimens are osteosclerotic, which resembles the microanatomy of long bones in all studied taxa. The proximal to medial part of ribs mainly consists of a compact periosteal cortex surrounding an inner endosteal territory. Toward the distal end of the ribs, the periosteal thickness decreases whereas the endosteal territory increases. Despite a shift from periosteal versus endosteal tissues, global rib compactness remains relatively constant. Osteosclerosis in ribs and vertebrae is reached by the same processes as in the long bones: by a relative increase in cortex thickness that is coupled by a reduction of the medullary cavity, by the persistence of calcified cartilage, and by an inhibition of remodeling although some resorption may occur but without complete redeposition of bone. Processes differ from those observed in Permian marine reptiles and some mosasaurines, where either extensive remodeling or inhibition of bone resorption leads to osteosclerosis. Besides differences regarding the microanatomy, all studied bones of a taxon are consistent in their bone tissue type. Anat Rec, 302:1770-1791, 2019. © 2019 American Association for Anatomy.

Prognostic significance of a comprehensive histological evaluation of reticulin fibrosis, collagen deposition and osteosclerosis in primary myelofibrosis patients

AIMS

To evaluate whether a comprehensive histological evaluation of reticulin fibrosis, collagen deposition and osteosclerosis in bone marrow trephine biopsies (BMBs) of primary myelofibrosis (PMF) patients may have prognostic implications.

METHODS AND RESULTS

Reticulin fibrosis, collagen deposition and osteosclerosis were graded from 0 to 3 in a series of 122 baseline BMBs. Then, we assigned to each case a comprehensive score [reticulin, collagen, osteosclerosis (RCO) score, ranging from 0 to 9] that allowed us to distinguish two groups of patients, with low-grade (RCO score 0-4) and high-grade (RCO score 5-9) stromal changes. Of 122 patients, 88 displayed a low-grade and 34 a high-grade RCO score. The latter was associated more frequently with anaemia, thrombocytopenia, peripheral blood blasts and increased lactate dehydrogenase levels. The RCO score was correlated strictly with overall mortality (P = 0.013) and International Prognostic Scoring System (IPSS) risk categories, and was able to discriminate the overall survival of both low- and high-grade patients (log-rank test: P < 0.001). Moreover, it proved to be more accurate than the European Consensus on Grading of Bone Marrow Fibrosis (ECGMF grade) in identifying high-risk patients with poor prognosis. Finally, a combined analysis of RCO scores and IPSS risk categories in an integrated clinical-pathological evaluation was able to increase the positive predictive value (PPV) for mortality in high-risk patients.

CONCLUSION

The comprehensive RCO score, obtained by histological evaluation of reticulin fibrosis, collagen deposition and osteosclerosis was prognostically significant and more accurate than ECGMF grade in identifying high-risk patients and improved PPV when applied in addition to IPSS.

Pycnodysostosis: Clinicoradiographic Report of a Rare Case

Pycnodysostosis is an uncommon autosomal recessive sclerosing bone disorder which is characterized by short stature and generalized diffuse osteosclerosis. Patients usually have a large head with separated sutures, open fontanels, aplasia of frontal sinuses, obtuse mandibular gonial angle, and acroosteolysis of the distal phalanges. This case report showed a 25-year-old female with features pathognomonic of pycnodysostosis. The emphasis is mainly on the early diagnosis as it has an important role in the general health of such patients and prevention of complications.

Erdheim-Chester Disease: A Rare Presentation of a Rare Disease

Erdheim-Chester disease (ECD) is a rare, xanthogranulomatous, non-Langerhans cell histiocytosis with frequent systemic involvement. Although the diagnosis is based on characteristic histological and radiological findings, its identification can be challenging because of its heterogeneous presentation. Osteosclerosis of long bones, often associated with bone pain, is the most common initial manifestation, followed by extraskeletal manifestations in approximately 50% of cases. There is no standard treatment for ECD, although recommendations have been made on the basis of small studies. A systematic approach to the diagnosis of ECD is important, because its manifestations may be life-threatening and may require specific management. We report an atypical presentation of ECD, with early cardiac, renal, and central nervous system involvement, and only late skeletal manifestations.

Elevated marrow inflammatory cells and osteoclasts in subchondral osteosclerosis in human knee osteoarthritis

Subchondral osteosclerosis, characterized by an increase of hypomineralized bone material, is a pathological hallmark of osteoarthritis. The cellular components in the subchondral marrow compartment that participate in this aberrant bone remodeling process remain to be elucidated. This study assessed the presence of marrow inflammatory cells and their relative abundance between nonsclerotic and sclerotic tissues in knee osteoarthritis. Bone samples from osteoarthritic knee tibial plateaus were stratified for histological analyses using computed tomography osteoabsorptiometry. Immunohistological analysis revealed the presence of CD20 (B-lymphocyte) and CD68 (macrophage), but not CD3 (T-lymphocyte) immunoreactive mononuclear cells in subchondral marrow tissues and their relative abundance was significantly increased in sclerotic compared with nonsclerotic bone samples. Multinucleated osteoclasts that stained positive for CD68 and tartrate-resistant acid phosphatase, predominantly associated with CD34-positive blood vessels and their abundance was strongly increased in sclerotic samples. Bone-specific alkaline phosphatase activity in outgrowth osteoblasts was induced by conditioned medium from nonsclerotic, but not sclerotic, bone pieces. These results suggest that an interaction between bone-resident cells and marrow inflammatory cells might play a role in aberrant bone remodeling leading to subchondral osteosclerosis. Elevated osteoclast activity in sclerotic bone suggests that bone formation and resorption activities are increased, yet uncoupled, in human knee osteoarthritis.

Acute Myeloid Leukemia with Isolated Trisomy 19 Associated with Diffuse Myelofibrosis and Osteosclerosis

Primary myelofibrosis (PMF), per WHO criteria, is a clonal myeloproliferative neoplasm that usually presents with a proliferation of granulocytic and megakaryocytic lineages with an associated fibrous deposition and extramedullary hematopoiesis. The bone marrow histologic findings of this disorder are typically characterized by the presence of myeloid metaplasia with an associated reactive fibrosis, angiogenesis, and osteosclerosis. However, marked myelofibrosis is not solely confined to PMF and may also be associated with other conditions including but not limited to acute megakaryoblastic leukemias (FAB AML-M7). Here, we describe a rare case of a non-megakaryoblastic acute myeloid leukemia with marked myelofibrosis with osteosclerosis and an isolated trisomy 19. A 19-year-old male presented with severe bone pain of one week duration with a complete blood cell count and peripheral smear showing a mild anemia and occasional circulating blasts. A follow up computed tomography (CT) scan showed diffuse osteosclerosis with no evidence of hepatosplenomegaly or lymphadenopathy. Subsequently, the bone marrow biopsy showed markedly sclerotic bony trabeculae and a hypercellular marrow with marked fibrosis and intervening sheets of immature myeloid cells consistent with myeloblasts with monocytic differentiation. Importantly, these myeloblasts were negative for megakaryocytic markers (CD61 and vWF), erythroid markers (hemoglobin and E-cadherin), and lymphoid markers (CD3, CD19, and TdT). Metaphase cytogenetics showed an isolated triosomy 19 with no JAK2 V617F mutation. The patient was treated with induction chemotherapy followed by allogenic hematopoietic stem cell transplantation which subsequently resulted in a rapid resolution of bone marrow fibrosis, suggesting graft-anti-fibrosis effect. This is a rare case of a non-megakaryoblastic acute myeloid leukemia with myelofibrosis and osteosclerosis with trisomy 19 that may provide insights into the prognosis and therapeutic options of future cases.

Problems and pitfalls in grading of bone marrow fibrosis, collagen deposition and osteosclerosis - a consensus-based study

AIMS

In the era of potentially disease-modifying agents such as Janus kinase inhibitors, accurate grading and differentiation of bone marrow (BM) fibrosis has become more relevant to assess staging of disease and therapeutic effects. However, different fibrosis grading models have been used in the past without uniformity, including the proposal by the World Health Organization. Current scoring systems are based only on reticulin fibrosis. Therefore, additional assessment of collagen and the grade of osteosclerosis appear to be essential to discriminate all components of the complex BM fibrous matrix.

METHODS AND RESULTS

We evaluated problems and pitfalls regarding staining techniques and the interpretation of reticulin fibrosis on a total of 352 samples. Furthermore, we propose a minor modification of the current grading and separate scoring for collagen deposition and osteosclerosis. Reproducibility of gradings was tested among 11 haematopathologists in a blinded assessment. Overall, the inter-rater reliability of all three grading systems ranged between 0.898 and 0.926.

CONCLUSIONS

A standardized assessment of BM fibrosis with differentiation between reticulin, collagen and osteosclerosis is recommended to evaluate the various components of the fibrous matrix which may be delinked after therapy. In this regard, quality of staining and application of laboratory standards enable a highly reproducible scoring.

Beyond osteogenesis imperfecta: Causes of fractures during infancy and childhood

Fractures in infancy or early childhood require prompt evaluation with consideration of accidental or non-accidental trauma as well as a large number of genetic disorders that predispose to fractures. Bone fragility has been reported in more than 100 genetic disorders, including skeletal dysplasias, inborn errors of metabolism and congenital insensitivity to pain. Most of these disorders are rare but often have distinctive clinical or radiographic findings to assist in the diagnosis. Gene sequencing is available, albeit connective tissue and skeletal dysplasia panels and biochemical studies are only helpful in a minority of cases. This article presents the clinical, radiographic, and molecular profiles of the most common heritable disorders other than osteogenesis imperfecta with increased bone fragility. In addition, the clinicians must consider non-heritable influences such as extreme prematurity, prenatal viral infection and neoplasia in the diagnostic process.

Report of a case of Raine syndrome and literature review

We report on a case of Raine syndrome with a mutation in FAM20C and typical phenotypic features consisting of midface hypoplasia, hypoplastic nose, choanal atresia, wide fontanelle, exophthalmos, generalized osteosclerosis and intracranial calcification. New features in our patient are cerebellar hypoplasia and pachygyria. We review the literature and conclude that the triad of hypoplastic nose, exophthalmos and generalized osteosclerosis and/or intracranial calcification is consistent in all molecularly confirmed cases.

Diagnostic dilemma: osteopetrosis with superimposed rickets causing neonatal hypocalcemia

Osteopetrosis is a rare genetic condition of reduced osteoclastic bone resorption which causes defective bone remodeling and skeletal sclerosis during growth, having effects on many organs and tissues. Mutation of T-cell immune regulator 1 (TCRG1) gene is the most common genetic defect leading to osteopetrosis, with poor prognosis. The autosomal recessive form presents in the infantile period (also known as malignant infantile osteopetrosis--MIOP), and is characterized by fractures, short stature, hepatosplenomegaly, compressive neuropathies, hypocalcemia and pancytopenia. Being a rare disease with non-specific clinical manifestations, the diagnosis is difficult and usually delayed. Rickets is a characteristic feature of MIOP which results from the defect in osteoclasts to provide a normal Ca/P balance resulting in the poor mineralization of the osteoid. Various treatment options have been suggested for osteopetrosis, but hematopoietic stem cell transplantation still remains the only curative treatment option presently. The authors report the case of a 46-day-old girl with late-onset neonatal hypocalcemia and rickets that was later diagnosed as osteopetrosis. This case report emphasizes that infantile osteopetrosis is an important cause of neonatal hypocalcemia. As irreversible complications develop within the first months of life, immediate diagnosis and early intervention are crucial and may be life-saving.

An infant with splenohepatomegaly: a rare cause

Osteopetrosis is a rare congenital disorder of bone resorption, caused by failure of osteoclasts to reabsorb immature bone. Malignant infantile osteopetrosis presents in early life with generalized osteosclerosis and decreased bone marrow spaces, resulting in anemia, splenohepatomegaly due to extramedullary hematopoiesis, cranial nerve compression, and growth failure. It is a fatal condition with death occurring within the first year of life. Bone marrow transplant remains the only curative treatment. We present a report of an infant with splenohepatomegaly, who was diagnosed with malignant infantile osteopetrosis.

An osteosclerotic form of Robinow syndrome

Robinow syndrome (RS) is a clinically and genetically heterogenous condition primarily characterized by short stature, mesomelia, genital hypoplasia, oral abnormalities, and a facial gestalt that includes hypertelorism, a short nose, and a broad mouth. The disorder exists in both a dominant and a more severe recessive form. Here two unrelated cases of sporadic RS are described with the additional finding of axial and appendicular osteosclerosis. These two patients, coupled with three additional patients previously described in the literature, may represent a distinct sub-phenotype of this condition.

Raine syndrome

Raine syndrome is a rare genetic disorder with characteristic features of exophthalmos, choanal atresia or stenosis, osteosclerosis and cerebral calcifications. Most of babies with this disorder die immediately after birth. We report a baby who was 7 weeks old at the time of presentation.

Gradual adaptation of bone structure to aquatic lifestyle in extinct sloths from Peru

Non-pathological densification (osteosclerosis) and swelling (pachyostosis) of bones are the main modifications affecting the skeleton of land vertebrates (tetrapods) that returned to water. However, a precise temporal calibration of the acquisition of such adaptations is still wanting. Here, we assess the timing of such acquisition using the aquatic sloth Thalassocnus, from the Neogene of the Pisco Formation, Peru. This genus is represented by five species occurring in successive vertebrate-bearing horizons of distinct ages. It yields the most detailed data about the gradual acquisition of aquatic adaptations among tetrapods, in displaying increasing osteosclerosis and pachyostosis through time. Such modifications, reflecting a shift in the habitat from terrestrial to aquatic, occurred over a short geological time span (ca 4 Myr). Otherwise, the bones of terrestrial pilosans (sloths and anteaters) are much more compact than the mean mammalian condition, which suggests that the osteosclerosis of Thalassocnus may represent an exaptation.

Identification of the first deletion in the LRP5 gene in a patient with autosomal dominant osteopetrosis type I

In the last decade, the low-density lipoprotein receptor-related protein 5 (LRP5) gene, coding for a coreceptor in the canonical Wnt signalling pathway, has been shown to play an important role in regulating bone mass and to be involved in the pathogenesis of several bone disorders. Here we describe a patient who presented with a clinical picture of Autosomal Dominant Osteopetrosis type I (ADO I), in whom we could identify the first deletion in the LRP5 gene causing increased bone mass. This mutation caused the in-frame deletion of two amino acids in the fourth blade of the first propeller of the protein, namely the highly conserved glycine at position 171 and the following glutamate residue. In vitro studies suggested that the pathogenic effect of this novel mutation could be due to a decreased inhibition of Wnt signalling by the antagonistic proteins sclerostin and Dickkopf-1, encoded respectively by the SOST and DKK1 genes, in the presence of mutated LRP5. Our results highlight an increasing molecular heterogeneity in LRP5-related bone diseases.

Osteopetrosis-A rare entity with osteomyelitis

Osteopetrosis is a rare genetic disorder that causes generalized sclerosis of the bone due to defect in bone resorption and remodeling. Albergs-Schonberg disease or autosomal dominant osteopetrosis type II is a rare form of osteopetrosis. Osteomyelitis is a well-documented complication of osteopetrosis. Any associated dental abnormality may be attributed to the pathological changes in bone remodeling. This case report discusses a case of osteopetrosis with osteomyelitis as a complication in a 8-year-old boy.

Camurati-Engelmann disease: unique variant featuring a novel mutation in TGFβ1 encoding transforming growth factor beta 1 and a missense change in TNFSF11 encoding RANK ligand

We report a 32-year-old man and his 59-year-old mother with a unique and extensive variant of Camurati-Engelmann disease (CED) featuring histopathological changes of osteomalacia and alterations within TGFβ1 and TNFSF11 encoding TGFβ1 and RANKL, respectively. He suffered leg pain and weakness since childhood and reportedly grew until his late 20s, reaching 7 feet in height. He had deafness, perforated nasal septum, torus palatinus, disproportionately long limbs with knock-knees, low muscle mass, and pseudoclubbing. Radiographs revealed generalized skeletal abnormalities, including wide bones and cortical and trabecular bone thickening in keeping with CED, except that long bone ends were also affected. Lumbar spine and hip BMD Z-scores were + 7.7 and + 4.4, respectively. Biochemical markers of bone turnover were elevated. Hypocalciuria accompanied low serum 25-hydroxyvitamin D (25[OH]D) levels. Pituitary hypogonadism and low serum insulin-like growth factor (IGF)-1 were present. Karyotype was normal. Despite vitamin D repletion, iliac crest histology revealed severe osteomalacia. Exon 1 of TNFRSF11A (RANK), exons 2, 3, and 4 of LRP5, and all coding exons and adjacent mRNA splice junctions of TNFRSF11B (OPG), SQSTM1 (sequestosome 1), and TNSALP (tissue nonspecific alkaline phosphatase) were intact. His asymptomatic and less dysmorphic 5'11″ mother, also with low serum 25(OH)D, had milder clinical, radiological, biochemical, and histopathological findings. Both individuals were heterozygous for a novel 12-bp duplication (c.27_38dup, p.L10_L13dup) in exon 1 of TGFβ1, predicting four additional leucine residues in the latency-associated-peptide segment of TGFβ1, consistent with CED. The son was also homozygous for a single base transversion in TNFSF11, predicting a nonconservative amino acid change (c.107C > G, p.Pro36Arg) in the intracellular domain of RANKL that was heterozygous in his nonconsanguineous parents. This TNFSF11 variant was not found in the SNP Database, nor in published TNFSF11 association studies, but it occurred in four of the 134 TNFSF11 alleles (3.0%) we tested randomly among individuals without CED. Perhaps the unique phenotype of this CED family is conditioned by altered RANKL activity.

Dysosteosclerosis presents as an "osteoclast-poor" form of osteopetrosis: comprehensive investigation of a 3-year-old girl and literature review

Dysosteosclerosis (DSS), an extremely rare dense bone disease, features short stature and fractures and sometimes optic atrophy, cranial nerve palsy, developmental delay, and failure of tooth eruption in infancy or early childhood consistent with osteopetrosis (OPT). Bone histology during childhood shows unresorbed primary spongiosa from deficient osteoclast action. Additionally, there is remarkable progressive flattening of all vertebrae and, by adolescence, paradoxical metaphyseal osteopenia with thin cortical bone. Reports of consanguinity indicate autosomal recessive inheritance, yet more affected males than females suggest X-linked recessive inheritance. We investigated a nonconsanguineous girl with DSS. Osteosclerosis was discovered at age 7 months. Our studies, spanning ages 11 to 44 months, showed weight at approximately 50th percentile, and length diminishing from approximately 30th percentile to -2.3 SD. Head circumference was +4 SD. The patient had frontal bossing, blue sclera, normal teeth, genu valgum, and unremarkable joints. Radiographs showed orbital and facial sclerosis, basilar thickening, bone-in-bone appearance of the pelvis, sclerotic long bone ends, and fractures of ribs and extremities. Progressive metaphyseal widening occurred as vertebrae changed from ovoid to flattened and became beaked anteriorly. A hemogram was normal. Consistent with OPT, serum parathyroid hormone (PTH) concentrations reflected dietary calcium levels. Serum bone alkaline phosphatase, osteocalcin, and TRACP-5b were subnormal. The iliac crest contained excessive primary spongiosa and no osteoclasts. No mutations were identified in the splice sites or exons for the genes encoding chloride channel 7, T-cell immune regulator 1, OPT-associated transmembrane protein 1, and monocyte colony-stimulating factor (M-CSF) and its receptor C-FMS, ANKH, OPG, RANK, and RANKL. Genomic copy-number microarray was unrevealing. Hence, DSS is a distinctive OPT of unknown etiology featuring osteoclast deficiency during early childhood. How osteopenia follows is an enigma of human skeletal pathobiology.

Osteosclerosis owing to Notch gain of function is solely Rbpj-dependent

Osteosclerosis is a pathologic bone disease characterized by an increase in bone formation over bone resorption. Genetic factors that contribute to the pathogenesis of this disease are poorly understood. Dysregulation or mutation in many components of the Notch signaling pathway results in a wide range of human developmental disorders and cancers, including bone diseases. Our previous study found that activation of the Notch signaling in osteoblasts promotes cell proliferation and inhibits differentiation, leading to an osteosclerotic phenotype in transgenic mice. In this study we report a longer-lived mouse model that also develops osteosclerosis and a genetic manipulation that completely rescues the phenotype. Conditionally cre-activated expression of Notch1 intracellular domain (NICD) in vivo exclusively in committed osteoblasts caused massive osteosclerosis with growth retardation and abnormal vertebrae. Importantly, selective deletion of a Notch nuclear effector--Rbpj--in osteoblasts completely suppressed the osteosclerotic and growth-retardation phenotypes. Furthermore, cellular and molecular analyses of bones from the rescued mice confirmed that NICD-dependent molecular alterations in osteoblasts were completely reversed by removal of the Rbpj pathway. Together, our observations show that the osteosclerosis owing to activation of Notch signaling in osteoblasts is canonical in nature because it depends solely on Rbpj signaling. As such, it identifies Rbpj as a specific target for manipulating Notch signaling in a cell-autonomous fashion in osteoblasts in bone diseases where Notch may be dysregulated.