Bizarre parosteal osteochondromatous proliferation in the distal ulna where the lesion is continuous with the medullary cavity: a case report.

BACKGROUND: Bizarre parosteal osteochondromatous proliferation (BPOP) is a rare benign bone tumor, it is also called "Nora's lesion". The lesion is characterized by heterotopic ossification of the normal bone cortex or parosteal bone. The etiology of BPOP is unclear and may be related to trauma. In most BPOPs, the lesion is not connected to the medullary cavity. Here we report an atypical case, characterized by reversed features compared to the typical BPOP, which demonstrated continuity of the lesion with the cavity. CASE PRESENTATION: An 11-year-old female child had a slow-growing mass on her right wrist for 8 months with forearm rotation dysfunction. Plain X-rays showed an irregular calcified mass on the right distal ulna, and computed tomography (CT) showed a pedunculated mass resembling a mushroom protruding into the soft tissue at the distal ulna. The medulla of this lesion is continuous with the medulla of the ulna. A surgical resection of the lesion, together with a portion of the ulnar bone cortex below the tumor was performed, and the final pathology confirmed BPOP. After the surgery, the child's forearm rotation function improved significantly, and there was no sign of a recurrence at 1-year follow-up. CONCLUSION: It is scarce for BPOP lesions to communicate with the medullary cavity. However, under-recognition of these rare cases may result in misdiagnosis or inappropriate treatment thereby increasing the risk of recurrence. Therefore, special cases where BPOP lesions are continuous with the medulla are even more important to be studied to understand better and master these lesions. Although BPOP is a benign tumor with no evidence of malignant transformation, the recurrence rate of surgical resection is high. We considered the possibility of this particular disease prior to surgery and performed a surgical resection with adequate safety margins. Regular postoperative follow-up is of utmost importance, without a doubt.

BPOP in early childhood following resection of osteochondroma: report of a case.

The diagnosis of an osteochondroma in the short bones of the extremities is atypical and the presentation in infancy is unusual. A 3-month-old female presented for evaluation of radial deviation of the right index finger present since birth. Radiographs showed a broad-based osseous outgrowth with the usual features of an osteochondroma arising from the base of middle phalanx. Initial corrective surgery at 22 months was followed by recurrence of the lesion. Another resection at 4 years confirmed a final diagnosis of BPOP (bizarre parosteal osteochondromatous proliferation). The subsequent pathologic diagnosis of BPOP appears to support the hypotheses concerning the etiology of BPOP as possibly arising from repeated trauma to the metaphysis.

Analysis of the Actions of RARγ Agonists on Growing Osteochondromas in a Mouse Model.

The actions of the retinoic acid nuclear receptor gamma (RARγ) agonist, palovarotene, on pre-existing osteochondromas were investigated using a mouse multiple osteochondroma model. This approach was based on the knowledge that patients often present to the clinic after realizing the existence of osteochondroma masses, and the findings from preclinical investigations are the effects of drugs on the initial formation of osteochondromas. Systemic administration of palovarotene, with increased doses (from 1.76 to 4.0 mg/kg) over time, fully inhibited tumor growth, keeping the tumor size (0.31 ± 0.049 mm3) similar to the initial size (0.27 ± 0.031 mm3, p = 0.66) while the control group tumor grew (1.03 ± 0.23 mm3, p = 0.023 to the drug-treated group). Nanoparticle (NP)-based local delivery of the RARγ agonist also inhibited the growth of osteochondromas at an early stage (Control: 0.52 ± 0.11 mm3; NP: 0.26 ± 0.10, p = 0.008). Transcriptome analysis revealed that the osteoarthritis pathway was activated in cultured chondrocytes treated with palovarotene (Z-score = 2.29), with the upregulation of matrix catabolic genes and the downregulation of matrix anabolic genes, consistent with the histology of palovarotene-treated osteochondromas. A reporter assay performed in cultured chondrocytes demonstrated that the Stat3 pathway, but not the Stat1/2 pathway, was stimulated by RARγ agonists. The activation of Stat3 by palovarotene was confirmed using immunoblotting and immunohistochemistry. These findings suggest that palovarotene treatment is effective against pre-existing osteochondromas and that the Stat3 pathway is involved in the antitumor actions of palovarotene.

Long-term outcome of total hip arthroplasty in patients with multiple hereditary exostosis.

BACKGROUND: Multiple hereditary exostosis (MHE) is a rare autosomal dominant disorder characterized by multiple osteochondromas. There is a paucity of literature concerning total hip arthroplasty (THA) in patients with MHE. The aim of this study is to report long-term outcomes of THA in patients with MHE. METHODS: Fourteen patients undergoing 15 THA's for the treatment of osteoarthritis in the presence of osteochondromas and proximal femoral deformity secondary to MHE were reviewed. Mean age at the time of surgery and follow-up was 56 and 12 years. Seven (47%) had uncemented femoral components. Eleven hips had coxa valga on preoperative imaging. Clinical outcomes were assessed with both Harris hip scores (HHS) and Musculoskeletal Tumor Society Scores (MSTS). RESULTS: Following surgery, there was an improvement in the HHS (48-82, p < 0.01) and MSTS scores (41-70%, p < 0.01). Complications occurred in 5 patients leading to reoperation in 3 patients, of which 2 patients underwent a revision procedure at 19 and 20-years postoperative. The 10-year revision free survival was 100%. CONCLUSIONS: THA in the setting of MHE reliably improves patient function. One in three patients will have a postoperative complication; however, the long-term incidence of revision is low.

De Novo SOX6 Variants Cause a Neurodevelopmental Syndrome Associated with ADHD, Craniosynostosis, and Osteochondromas.

SOX6 belongs to a family of 20 SRY-related HMG-box-containing (SOX) genes that encode transcription factors controlling cell fate and differentiation in many developmental and adult processes. For SOX6, these processes include, but are not limited to, neurogenesis and skeletogenesis. Variants in half of the SOX genes have been shown to cause severe developmental and adult syndromes, referred to as SOXopathies. We here provide evidence that SOX6 variants also cause a SOXopathy. Using clinical and genetic data, we identify 19 individuals harboring various types of SOX6 alterations and exhibiting developmental delay and/or intellectual disability; the individuals are from 17 unrelated families. Additional, inconstant features include attention-deficit/hyperactivity disorder (ADHD), autism, mild facial dysmorphism, craniosynostosis, and multiple osteochondromas. All variants are heterozygous. Fourteen are de novo, one is inherited from a mosaic father, and four offspring from two families have a paternally inherited variant. Intragenic microdeletions, balanced structural rearrangements, frameshifts, and nonsense variants are predicted to inactivate the SOX6 variant allele. Four missense variants occur in residues and protein regions highly conserved evolutionarily. These variants are not detected in the gnomAD control cohort, and the amino acid substitutions are predicted to be damaging. Two of these variants are located in the HMG domain and abolish SOX6 transcriptional activity in vitro. No clear genotype-phenotype correlations are found. Taken together, these findings concur that SOX6 haploinsufficiency leads to a neurodevelopmental SOXopathy that often includes ADHD and abnormal skeletal and other features.

Non-osteopenic Bone Pathology After Allo-hematopoietic Stem Cell Transplantation in Patients with Inborn Errors of Immunity.

PURPOSE: There is a lack of data on post-HSCT non-osteopenic bone pathology specifically for children with inborn errors of immunity (IEI). We collected data on non-osteopenic bone pathology in children with IEI post-HSCT over two decades in a large tertiary pediatric immunology center. METHODS: Descriptive study with data analysis of bone pathology in allo-HSCT for IEI was performed between 1/1/2000 to 31/12/2018 including patients alive at follow-up to July 2022. Records were analyzed for bone pathology and risk factors. Exclusion criteria included isolated reduced bone density, fractures, and skeletal anomalies due to underlying IEI and short stature without other bone pathology. Bone pathologies were divided into 5 categories: bone tumors; skeletal dysplasia; avascular necrosis; evolving bone deformities; slipped upper femoral epiphysis. RESULTS: A total of 429 children received HSCT between 2000 and 2018; 340 are alive at last assessment. Non-osteopenic bone pathology was observed post-HSCT in 9.4% of patients (32/340, mean 7.8 years post-HSCT). Eleven patients (34%) had > 1 category of bone pathology. Seventeen patients (17/32; 53%) presented with bilateral bone pathology. The majority of patients received treosulfan-based conditioning (26/32; 81.2%). Totally, 65.6% (21/32) of patients had a history of prolonged steroid use (> 6 months). Pain was the presenting symptom in 66% of patients, and surgical intervention was required in 43.7%. The highest incidence of bone pathologies was seen in Wiskott-Aldrich syndrome (WAS) (n = 8/34; 23.5%) followed by hemophagocytic lymphohistiocytosis patients (n = 3/16; 18.8%). CONCLUSION: Non-osteopenic bone pathology in long-term survivors of allo-HSCT for IEI is not rare. Most patients did not present with complaints until at least 5 years post-HSCT highlighting the need for ongoing bone health assessment for patients with IEI. Children presenting with stunted growth and bone pathology post-HSCT should undergo skeletal survey to rule out development of post-HSCT skeletal dysplasia. Increased rates and complexity of bone pathology were seen amongst patients with Wiskott-Aldrich syndrome.

The role of vascular surgeons in the management of pediatric bone tumors.

OBJECTIVES: The objective of this study was to review the outcomes of a multidisciplinary approach to the surgical management of pediatric bone tumors with blood vessel involvement over a 14- year period. METHODS: A retrospective review was conducted of all pediatric bone tumor resections performed with the assistance of vascular surgery at our institution between January 2006 and January 2021. Inclusion criteria for the study included the presence of a vascular surgeon at the operative resection and radiographic evidence of major blood vessel involvement. RESULTS: From 2006 to 2021, 117 patients underwent a bone tumor resection by a single orthopedic surgeon/vascular surgeon team. Sixty were malignant tumors, and 57 were benign. Of the 117 procedures, 5.1% (6/117) required reconstruction of an artery; five in malignant cases and one in benign. No venous reconstructions were undertaken in this study. Ligation of a major artery without reconstruction was performed in 8.8% (5/57) of malignant and 1.7% (1/60) of benign resections. Despite this vessel-sparing approach, microscopic margins were clear in all cases. Local recurrence occurred in a single patient in the malignant group at 61 months. CONCLUSIONS: The ideal management of pediatric bone tumors with major blood vessel involvement remains poorly defined. Our results demonstrate that even in the setting of radiographic evidence of vessel involvement, a multidisciplinary team of vascular and orthopedic surgeons can employ a vessel-sparing approach with minimal blood loss, excellent limb salvage, and minimal local recurrence.

Benign Brain and Spinal Tumors Originating from Bone or Cartilage.

Benign osseocartilaginous tumors of the spine are overall uncommon, representing between 1 and 13% of all primary bone tumors and less than 10% of all spinal tumors. Tumors in this category include osteoblastic lesions such as the related osteoid osteoma and osteoblastoma, and cartilage-forming lesions including osteochondroma, chondroma, and chondroblastoma. Aneurysmal bone cysts, giant cell tumors of bone, and eosinophilic granulomas also comprise benign tumors of the spine arising from bone. There is significant heterogeneity in the epidemiology, molecular biology, imaging features, and optimal treatment of these lesions. For example, osteoid osteoma is characterized by high expression of the cyclooxygenase enzymes, making it amenable to treatment with anti-inflammatory drugs initially, whereas other lesions such as osteoblastoma may require intralesional curettage or en bloc resection sooner. Generally, en bloc resection is preferred when possible to minimize risk of recurrence. Further, some tumors may arise in the setting of syndromic conditions, such as multiple chondromas arising in Ollier disease or Maffucci syndrome, or as part of genetic disorders, such as osteochondromas in the context of hereditary multiple exostosis. These lesions may present with local pain, cause neurological compromise or be discovered incidentally on routine imaging. The Enneking classification and Weinstein-Boriani-Biagini system are routinely used to classify lesions and assist in surgical planning. More novel techniques such as radiofrequency ablation and laser photocoagulation have been applied for the treatment of osteoid osteoma and may have utility in the treatment of other lesion types. A multidisciplinary approach is critical in the management of benign lesions of the spine, and both chemotherapeutic and surgical approaches are routinely used.

Fluoride exposure and prevalence of osteochondroma in drinking water Endemic fluorosis areas of Heilongjiang Province, China: a cross-sectional study.

To investigate the relationship between fluoride exposure and Osteochondroma (OC) prevalence, a cross-sectional study was conducted in drinking water endemic fluorosis areas of Heilongjiang Province, China. Our study first reported that the prevalence of OC was 2.3% in drinking water endemic fluorosis areas of Heilongjiang Province, China, and no difference in gender. Logistic regression analysis found that compared to 1st quartile participants, the prevalence of OC was 73% lower in the 2nd quartile participants of WF (Water fluoride), and 3.4 times higher among the 2nd quartile UF (Urinary fluoride) participants. Our study suggests that 0.259-0.420 mg/L of WF may be considered an appropriate level for reducing OC prevalence, while UF (≥0.750 mg/L) could slightly increase the prevalence of OC. In summary, the link between fluoride and OC prevalence is complicated and needs to be further investigated in a cohort population.

Osteochondroma Pathogenesis: Mouse Models and Mechanistic Insights into Interactions with Retinoid Signaling.

Osteochondromas are cartilage-capped tumors that arise near growing physes and are the most common benign bone tumor in children. Osteochondromas can lead to skeletal deformity, pain, loss of motion, and neurovascular compression. Currently, surgery is the only available treatment for symptomatic osteochondromas. Osteochondroma mouse models have been developed to understand the pathology and the origin of osteochondromas and develop therapeutic drugs. Several cartilage regulatory pathways have been implicated in the development of osteochondromas, such as bone morphogenetic protein, hedgehog, and WNT/ß-catenin signaling. Retinoic acid receptor-γ is an important regulator of endochondral bone formation. Selective agonists for retinoic acid receptor-γ, such as palovarotene, have been investigated as drugs for inhibition of ectopic endochondral ossification, including osteochondromas. This review discusses the signaling pathways involved in osteochondroma pathogenesis and their possible interactions with the retinoid pathway.

Role of nuclear factor of activated T cells in chondrogenesis osteogenesis and osteochondroma formation.

PURPOSE: Nuclear factor of activated T cells (NFATc) are transcription factors that play a function in the immune response and in osteoclast differentiation. In the present work, we define the function of NFATc2 in chondrogenic and osteogenic cells. METHODS: Nfatc2loxP/loxP and Nfatc1loxP/loxP;Nfatc2loxP/loxP conditional mice were crossed with Prx1-Cre transgenics to inactivate Nfatc2 singly and with Nfatc1. Femurs and vertebrae were examined by microcomputed tomography (µCT) X-Ray images and histology and analyzed for the presence of osteochondromas. RESULTS: µCT demonstrated that Prx1-Cre;Nfatc2∆/∆ female mice had transient osteopenia and male mice did not have a cancellous or a cortical bone phenotype when compared to control mice. In contrast, the dual inactivation of Nfatc1 and Nfatc2 in Prx1-expressing cells resulted in cancellous osteopenia and small bones at 1 month of age in both sexes. Nfatc1;Nfatc2 deleted mice exhibited a ~ 50% decrease in bone volume and connectivity. Total bone area, periosteal and endocortical bone perimeters and femoral length were reduced indicating smaller bones. As the mice matured, the shortening of the femoral length persisted, but the osteopenic phenotype resolved and cancellous femoral bone of 4-month-old Nfatc1;Nfatc2 deleted mice was not different from controls although male mice had vertebral osteopenia. In addition, Nfatc1;Nfatc2 deleted mice displayed distortion of the distal metaphysis and, as they matured, the articular presence of mineralized tumors with the appearance of osteochondromas. CONCLUSION: Our studies reveal that NFATc1 and NFATc2 are necessary for optimal bone homeostasis and the suppression of osteochondroma formation.

A frameshift variant in the EXT1 gene in a feline leukemia virus-negative cat with osteochondromatosis.

Osteochondromatosis is a benign proliferative disorder characterized by cartilage-capped bony protuberances. In humans and most mammals, variants in the EXT1 or EXT2 gene are strongly correlated with the etiology of osteochondromatosis. However, in cats, osteochondromatosis has only been associated with feline leukemia virus infection. In this study, to explore other factors involved in the etiology of feline osteochondromatosis, we examined the EXT1 and EXT2 genes in a feline leukemia virus-negative cat with osteochondromatosis. Genetic analysis revealed a heterozygous single base pair duplication in exon 6 of the EXT1 gene (XM_023248762.2:c.1468dupC), leading to a premature stop codon in the EXT1 protein. Notably, this frameshift variant is recognized as one of the most common pathogenic variants in human osteochondromatosis. Our data suggest for the first time that genetic variants can have etiologic roles in osteochondromatosis in cats, as in humans and other animals.

Popliteal artery pseudoaneurysms in patients affected by osteochondroma.

Although exostosis or osteochondroma is a common bone tumor, associated vascular complications are rare. Clinical and radiological diagnoses are sometimes challenging, and there is no codification for surgical management. We report two cases of popliteal arterial pseudoaneurysms due to osteochondroma of the distal femur. A review of the current literature about case series and case reports of patients affected by arterial pseudoaneurysm complicating osteochondroma was also performed.

Ankle Mortise Instability in Multiple Hereditary Exostoses.

Ankle valgus is commonly reported in patients with multiple hereditary exostoses (MHE). We report the characteristics of mortise widening in MHE, its progression over time, and the resultant ankle pain and function at skeletal maturity. Mortise medial space (M), talocrural angle (TC), and tibiotalar angle (TT) measurements were collected on preoperative and last follow-up radiographs. Operative data and complications were recorded. American Orthopaedic Foot and Ankle Society (AOFAS) and short form-36 scores at skeletal maturity were collected. A total of 16 patients (19 ankles) had MHE and mortise widening. Thirteen patients had surgery. Preoperatively, no patient complained of instability. However, 11 ankles (57.9%) were painful and 15 (78.9%) were clinically in valgus. Patients underwent surgery at a mean age of 11.8 ± 2.2 y. Operative interventions included medial distal tibia hemiepiphysiodesis for the majority of patients. There were no statistically significant differences between pre and postoperative M, TC, TT angles. Operative patients showed an improved mean M (5.17 ± 1.17 to 4.63 ± 1.06 mm) and TT (8.71 ± 5.40° to 4.54 ±7.58°), however, neither angle reached normal values. TC representing fibular length-maintained measurements within normal limits (82.2 ± 5.3° to 84.8 ±5.8°). Questionnaires were obtained for 10 (52.6%) ankles. Mean age at questionnaires collection was 19.0 ± 3.6 y. Mean AOFAS score was 74.8 ± 17.6 out of 100. Patients scored 6.5 ± 4.1 out of 10 for alignment, 33.0 ± 6.7 out of 40 for pain, 35.3 ± 9.5 out of 50 for function. All short form-36 scores were above the national mean. Improvement of M and TT angles was modest. TC angle was within normal limits but showed an overall fibular shortening and decreased lateral buttress and potential for talar shift, as reflected in AOFAS score. The underwhelming amount of mortise widening correction achieved may not provide for a stable ankle joint.

Osteochondroma of the pubic symphysis causing hematuria: a case report and literature review.

BACKGROUND: Osteochondroma is the most common benign bone neoplasm and is sometimes referred to as osteocartilaginous exostosis. The symptoms caused by osteochondroma are rare, especially the urogenital complications. Therefore, this tumour is sometimes misdiagnosed. CASE PRESENTATION: This report described a 70-year-old woman with hematuria who was initially misdiagnosed with a bladder tumour in the outpatient department by a urologist. However, during cystoscopy, we found that the mass did not resemble a bladder tumor. Multidisciplinary approach with careful analysis of the imaging data suggested the diagnosis of osteochondroma. Open surgical excision of the mass was done and histology confirmed the diagnosis of benign osteochondroma. After 6 months of follow-up, the patient was still asymptomatic. CONCLUSIONS: This case illustrates that hematuria is caused by not only urogenital disease but also osteochondroma. We present this case to draw the attention of clinicians to osteochondroma of the pubic symphysis.

An unusual example of hereditary multiple exostoses: a case report and review of the literature.

BACKGROUND: Hereditary multiple exostoses (HME) is a rare skeletal disorder characterised by a widespread. distribution of osteochondromas originating from the metaphyses of long bones. CASE PRESENTATION: This case study examines a 55-year-old male cadaver bequeathed to the University of Liverpool who suffered from HME, thus providing an exceptionally rare opportunity to examine the anatomical changes associated with this condition. CONCLUSIONS: Findings from imaging and dissection indicated that this was a severe case of HME in terms of the quantity and distribution of the osteochondromas and the number of synostoses present. In addition, the existence of enchondromas and the appearance of gaps within the trabeculae of affected bones make this a remarkable case. This study provides a comprehensive overview of the morbidity of the disease as well as adding to the growing evidence that diseases concerning benign cartilaginous tumours may be part of a spectrum rather than distinct entities.

Pediatric rib pathologies: clinicoimaging scenarios and approach to diagnosis.

Pathologies involving the ribs are diverse in nature, including entities specific to the pediatric population as well as shared pathologies with adults. These can be either localized within or adjacent to the rib, but may also cause rib alteration as a component of a systemic process. To better understand these disorders, we discuss several common rib pathologies in the context of their clinical presentation and pertinent imaging findings. In addition, we review the imaging modalities that may be used to evaluate the ribs. Encompassing both the clinical and imaging aspects of pediatric rib pathologies, this review aims to increase pediatric and musculoskeletal radiologists' awareness of the spectrum of disease and how to leverage a pattern-based approach.

An update on the imaging of diaphyseal aclasis.

Solitary osteochondromas are common, benign hyaline cartilage-capped exostoses that primarily arise from the metaphyses of long and flat bones. Diaphyseal aclasis is an autosomal dominant condition resulting from EXT1 or EXT2 gene mutations and is characterized by multifocal osteochondromas. These can result in a wide spectrum of complications, such as skeletal deformity, neurological and vascular complications, adventitial bursa formation, fracture, and rarely malignant transformation to peripheral chondrosarcoma. In this review, we outline in detail the multimodality imaging features of DA and its associated complications.

Paleopathological study of a podal osteochondroma from the prehistoric Hypogeum of Calaforno (Sicily).

In this article, we report a case of isolated podal osteochondroma from the prehistoric Hypogeum of Calaforno (Giarratana, Ragusa, Sicily). Although the phalanx exhibiting the benign tumoral mass comes from a context featuring several commingled remains, the very good state of preservation of this bone allowed us to perform a comprehensive study of the neoplasm by applying a multidisciplinary approach encompassing archeology, morphology, stereomicroscopy, and radiology. The results from this very ancient specimen have been assessed in the light of the available paleopathological literature and clinical implications currently encountered in modern patients.

Osteochondroma : the local effects and the management.

Osteochondroma is a common benign bone tumour, presenting as a single or multiple lesions, pedunculated or sessile type, mainly in 1st-2nd decades and mostly in males. The presented case series, studied the local effect of (osteochondroma) at the end of long bones with best line of treatment (RQ). Eighteen patients with osteochondromas, with an age range of 9- 45 years, mean age 19.6 ± 11.147 years, were seen from October 2016 to November 2018. There were 8 cases with painful lesion due to (mechanical interaction) or (pressure on near by neurovascular bundle), or from (inflamed bursa). Four cases were asymptomatic, 3 cases had Growth disturbances of the fellow bone, 3 cases presented with neurological symptoms and one case had vascular complications. Osteochondromas may present with different types of local effects on its surrounding tissues. Surgical excision is the best line of treatment.