Metachondromatosis is a rare autosomal dominant genetic disease with incomplete penetrance that involves abnormal function of the PTPN11 gene. Differentiation between chondrogenic tumors is a challenge for orthopedists. We report a case of a 5 year-old girl with metachondromatosis, a disease that shares attributes with osteochondromas and enchondromas. We found multiple osteochondroma-like lesions with the atypical characteristic of guiding its growth toward the neighboring joint (epyphisis) instead of moving away from it. Furthermore, columnar enchondroma-like lesions were clearly visible in the right distal radius, in the proximal femoral cervix and in the iliac crests. The patient reported that some other tumor had disappeared or downsized with time. This case was debated between a multidisciplinary skeletal dysplasia group. The aforementioned clinical and radiographic findings reinforced the hypothetical diagnosis of metachondromatosis. Definitive diagnosis of metachondromatosis requires a combination of clinical, radiographical and histopathological findings. Differential diagnosis between enchondromas, osteochondromas and metachondromatosis is vital due to differences in malignization and natural history. When a patient has multiple enchondromas and osteochondromas with regression of some lesions and atypical radiographical characteristic of the osteochondroma-like lesions pointing toward the epiphysis, metachondromatosis, a rare disease, must be considered. Surgical treatment is reserved for painful lesions Risk of malignization is insignificant and genetic advice must be given due it is an autosomal dominant disease.

We present a case of hereditary multiple exostoses with malignant transformation to chondrosarcoma in a woman complaining of enlargement and pain in the right thigh. Hereditary multiple exostoses is a rare genetic disorder characterized by multiple osteochondromas. Malignant transformation to chondrosarcoma of a pre-existing osteochondroma is a possible significant manifestation of this hereditary syndrome. Imaging modalities such as X-ray, Ultrasound, and computed tomography play a crucial role in the diagnosis and management of these patients, as described in this case.

UNASSIGNED: Dysplasia epiphysealis hemimelica is a rare non-inherited condition characterized by the unilateral predominance of osteochondromas in one or more epiphyses, with ankles and knees being the most affected joints. Treatment approaches vary based on the localization of the disease, encompassing both conservative and surgical options. Due to its rarity, there is a lack of definitive surgical guidelines or specific treatment modalities. Therefore, the objective of this systematic review was to thoroughly investigate dysplasia epiphysealis hemimelica to provide evidence-based guidance for managing this condition, specifically focusing on the foot and ankle.
UNASSIGNED: A systematic search was performed on PubMed and the Cochrane Library to identify all published articles related to dysplasia epiphysealis hemimelica of the foot and ankle. Individual patient information, such as gender, age, disease type, follow-up, localization, clinical presentation, intervention, and complications, were systematically extracted from each article and analyzed.
UNASSIGNED: Twenty-five eligible publications were included in the review, involving a total of 70 patients (16 females, 53 males). The mean age was 9.6 years (SD 7.3). The talus was the most prevalent location and clinical presentations included mass and pain in 54% of cases. Surgical procedures were chosen in 92% of patients, with 95% undergoing mass excision. Recurrence was the most frequent complication, observed in 9% of cases.
UNASSIGNED: Raising awareness about dysplasia epiphysealis hemimelica is crucial for early diagnosis and treatment, positively impacting clinical outcomes. Vigilant monitoring is essential during observational management, as unchecked mass growth can complicate surgical intervention. Surgical treatment focuses on mass excision, feasible even at a young age but requiring precision to prevent recurrence or secondary arthritis.
UNASSIGNED: IV.

BACKGROUND: Fibrodysplasia ossificans progressiva (FOP) is an extremely rare disease characterized by malformation of the bilateral great toes and progressive heterotopic ossification. The clinical features of FOP occur due to dysfunction of the bone morphogenetic protein (BMP) signaling pathway induced by the mutant activin A type I receptor/activin-like kinase-2 (ACVR1/ALK2) which contributes to the clinical features in FOP. Dysregulation of the BMP signaling pathway causes the development of osteochondroma. Poor awareness of the association between FOP and osteochondromas always results in misdiagnosis and unnecessary invasive operation.
METHODS: In this study, we present a case of classical FOP involving osteochondroma. An 18-year-old male adolescent, born with deformity of bilateral big toes, complained multiple masses on his back for 1 year. The mass initially emerged with a tough texture and did not cause pain. It was misdiagnosed as an osteochondroma. After two surgeries, the masses became hard and spread around the entire back region. Meanwhile, extensive heterotopic ossification was observed around the back, neck, hip, knee, ribs, and mandible during follow-up. Osteochondromas were observed around the bilateral knees. No abnormalities were observed in the laboratory blood test results. Whole exome sequencing revealed missense mutation of ACVR1/ALK2 (c.617G > A; p.R206H) in the patient and confirmed the diagnosis of FOP.
CONCLUSIONS: In summary, classical FOP always behaves as a bilateral deformity of the big toes, as well as progressive ectopic ossification and osteochondromas in the distal femur and proximal tibia. An understanding of the association between osteochondromas and FOP aids in diagnosis and avoids unnecessary invasive management in patients.

Osteochondromas (OCs) are developmental anomalies that originate from the periosteum and typically form during enchondral ossification near the joints. Retro-patellar OC caused by exostosis forms in various intracapsular, intra-tendon, and joint-adjacent positions within the knee joint. In this case, a 19-year-old male presented with swelling and a mass in his left knee, which raised suspicion of bone tumors. After evaluating x-ray images and conducting histopathological examinations, the diagnosis was confirmed as retro-patellar OC.

Background Hereditary multiple exostosis (HME) is a significantly rare genetic condition with benign chondrogenic lesions affecting long bones. Forearm involvement is relatively common, with varied treatment modalities reported. Here we describe our experience with HME. The study is the first of its kind to be conducted in the Middle East and Saudi Arabia. Methods A retrospective medical record-based case review was carried out on patients with forearm HME operated from 2006 to 2022 at our institution. Patient demographics, clinical presentation, management, outcome, Masada scale, and radiological outcomes were analysed.  Results Ten patients (12 affected forearms) with HME were included. The average age of those undergoing surgery was 12.7 ± 5.13 years, and the average length of follow-up was 62.25 months. Most patients (n = 5, 50%) had Masada type 1 (Type I indicates radial head not displaced, primary exostosis from the distal region of the ulna, ulna relatively short, radius bending). Five (50%) underwent radial head resection. The majority of the patients (n = 8, 80%) had no complications or recurrence. Two patients developed recurrence; the first one developed recurrent radial bone deformity and dislocation of the radial head and the second, who underwent excision with an iliac crest bone graft application, developed osteolysis of the bone graft with recurrent deformity. Conclusion HME is typically managed primarily by excision of the lesion at skeletal maturity and annual check-up and radiological follow-up. If a secondary procedure is needed in future, simple excision of the dislocated radial head would be the most feasible approach. Due to the rarity of the illness and limited literature, further studies are still required to optimize the outcome in children with HME.

UNASSIGNED: Hereditary multiple exostoses (HME) disease is hallmarked by cartilaginous osteochondromas secondary to an autosomal dominant mutation within the exostosin gene family. These outgrowths predominantly occur around the long bone physis. An associated disease is dysplasia epiphysealis hemimelica also known as Trevor\'s disease. Trevor\'s disease is hallmarked by intra-articular osteochondromas. While the two diseases are similar, they are not genetically related and often have differing patient presentations.
UNASSIGNED: We report on a case of a 7-year-old female with a familial history significant for HME that presented with an isolated chief complaint of elbow extension block secondary to osteochondromas found both intra-articular and at the olecranon fossa. We present what could be one of the first cases of coexisting HME and Trevor\'s disease of the upper extremity.
UNASSIGNED: Our patient\'s unique presentation of an intra-articular osteochondroma speculated to be a result of Trevor\'s disease, in the presence of an established HME diagnosis. Management for this patient did not deviate heavily from the established approach for HME which entails conservative observation until symptomatic. Due to the substantial loss of range of motion (ROM), surgical intervention took place in the form of exostoses removal and necessary reconstruction of the fossa. The patient\'s ROM subsequently was restored to near normal.

Hereditary Multiple Exostoses (HME), also known as Multiple Osteochondromas (MO) is a rare genetic disorder characterized by multiple benign cartilaginous bone tumors, which are caused by mutations in the genes for exostosin glycosyltransferase 1 (EXT1) and exostosin glycosyltransferase 2 (EXT2). The genetic defects have not been studied in the Saudi patients.
We investigated mutation spectrum of EXT1 and EXT2 in 22 patients from 17 unrelated families.
Genomic DNA was extracted from peripheral leucocytes. The coding regions and intron-exon boundaries of both EXT1 and EXT2 genes were screened for mutations by PCR-sequencing analysis. Gross deletions were analyzed by MLPA analysis.
EXT1 mutations were detected in 6 families (35%) and 3 were novel mutations: c.739G > T (p. E247*), c.1319delG (p.R440Lfs*4), and c.1786delA (p.S596Afs*25). EXT2 mutations were detected in 7 families (41%) and 3 were novel mutations: c.541delG (p.D181Ifs*89), c.583delG (p.G195Vfs*75), and a gross deletion of approximately 10 kb including promoter and exon 1. Five patients from different families had no family history and carried de novo mutations (29%, 5/17). No EXT1 and EXT2 mutations were found in the remaining four families. In total, EXT1 and EXT2 mutations were found in 77% (13/17) of Saudi HME patients.
EXT1 and EXT2 mutations contribute significantly to the pathogenesis of HME in the Saudi population. In contrast to high mutation rate in EXT 1 (65%) and low mutation rate in EXT2 (25%) in other populations, the frequency of EXT2 mutations are much higher (41%) and comparable to that of EXT1 among Saudi patients. De novo mutations are also common and the six novel EXT1/EXT2 mutations further expands the mutation spectrum of HME.

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UNASSIGNED: Hereditary multiple exostoses (HME) is an autosomal dominant disorder. The lesion in the proximal femoral metaphysis can bring about hip dysplasia and subsequent degenerative arthritis. Due to its rare prevalence, there have been a few case reports of total hip arthroplasty (THA) for osteoarthritis secondary to HME. The aim of this study was to report mid- to long-term outcomes of THA in HME patients and discuss special considerations that should be taken into account during surgery.
UNASSIGNED: We retrospectively evaluated the clinical and radiological results of THA for osteoarthritis secondary to HME in 11 hips of 9 patients after a minimum follow-up of 5 years (mean, 9.9 years). There were 3 men (3 hips) and 6 women (8 hips), with a mean age of 53.6 years (range, 46.8-58 years) at the index surgery in this study. Harris hip score (HHS) was used for clinical outcome assessment, and radiologically, implant stability, radiolucent lines, liner wear, and any sign of osteolysis or implant loosening were evaluated. Postoperative complications including infection, deep vein thrombosis, and dislocations were also investigated.
UNASSIGNED: Cemented stems and cementless cups with the conventional polyethylene liner were used in bilateral hips of a single patient. In the other cases, cementless implants were used with ceramic-on-ceramic bearings. The mean HHS improved from 34.8 preoperatively to 92.5 postoperatively. Polyethylene liner wear and osteolysis were observed in 1 patient with cemented stems. Radiolucent lines were observed in 2 different cases. However, the femoral stems remained stable. There were no surgery-related complications except heterotopic ossification during follow-up.
UNASSIGNED: Despite the several surgical considerations, the mid- to long-term clinical and radiological outcomes of THA in HME patients were satisfactory. The abnormal, wide mediolateral diameter of the proximal metaphysis should be considered in selecting and inserting the stem with adequate anteversion. Leg length discrepancy was also common, so teleradiographs should be obtained before surgery. Intraoperative leg length evaluation might be difficult due to the morphologic changes in the proximal femur after mass excision and individual bone length differences.