BACKGROUND: This review aims to study the clinical characteristics, diagnostic results, treatments, and outcomes in patients with heterotopic ossification following COVID-19 infection.
METHODS: A literature search for eligible articles was conducted using MEDLINE/Pubmed, Global Health, and Scopus databases (January 12th, 2023), including all case reports and case series from any country and language. The criteria for inclusion in this review were cases of COVID-19 infection subsequently developing heterotopic ossification.
RESULTS: This systematic review analysed 15 reports (n = 20 patients) documenting cases of heterotopic ossification following COVID-19 infection. 80% of the patients were male, with a median age of 59 years. All patients required intensive care unit stay with an average duration of 48.5 days. Mechanical ventilation was necessary for all patients and 30% of them underwent tracheostomy. Common symptoms included stiffness and pain, most frequently affecting multiple locations (70%), with the hips and shoulders being predominantly involved. X-rays were the most commonly used imaging modality, followed by computed tomography. Although treatment was given, some of the patients continued to experience symptoms, particularly stiffness.
CONCLUSIONS: 20 patients who developed heterotopic ossification after COVID-19 have been reported, the majority of which had at least two independent risk factors for this condition. The link between those two clinical entities is therefore uncertain, requiring further investigation. It is nonetheless important to suspect heterotopic ossification in patients with severe COVID-19 infection, prolonged immobilisation, mechanical ventilation, who develop joint pain and stiffness, as this condition can significantly impact patients\' quality of life.
BACKGROUND: CRD42023393516.

Myositis ossificans, a benign tumor composed of spindle cells and osteoblasts, can clinically and radiologically mimic osteosarcoma. While recognition and accurate diagnosis of myositis ossificans can be a challenge, this is critical as it may allow a conservative surgical approach to maximize functional outcomes. Herein, we present a patient with surface myositis ossificans confirmed genetically by the presence of COL1A1::USP6 gene fusion, along with a literature review. Due to the enhanced visualization of the bone matrix, computed tomography (CT) imaging may be a superior imaging modality to magnetic resonance (MR) imaging. Staged biopsies with samples obtained from the periphery and center of the lesions may allow pathologists to discern the zonal distribution histologically. Furthermore, immunohistochemistry fluorescence in situ hybridization and molecular testing can aid in the distinction of myositis ossificans from mimics. Because of their resemblance to other bone tumors, these cases of myositis ossificans highlight the importance of a multidisciplinary approach integrating clinical, radiologic, and pathologic analysis and involving serial imaging, sampling, and judicious use of ancillary immunohistochemical and molecular testing.

UNASSIGNED: Circumscribed or pseudomalignant myositis ossificans (MO) is a rare and benign condition characterized by heterotopic bone formation in soft tissues. The clinical presentation of MO, imaging investigations, histological findings, and treatment strategies are unclear, especially in the pediatric population.
UNASSIGNED: A literature search was conducted in PubMed, Scopus, and Google Scholar electronic databases to identify original articles and reviews in English or French of traumatic and non-traumatic MO. Studies were selected by 2 independent reviewers following the PRISMA recommendation and descriptive data were extracted. We harvest in each case the sex, age at diagnosis, location, presence of initial trauma, pre-emptive diagnosis, modalities of imagery used, realized biopsy, treatment performed, and type of follow-up.
UNASSIGNED: Sixty pediatric cases of MO were identified between 2002 and 2023. Twenty-three patients (38.3%) were diagnosed with idiopathic/pseudomalignant and 37 patients (61.7%) with circumscribed. The mean age at diagnosis was 9.5 years (range 0.2-17 years), with a male-to-female ratio of 1:1. The initial pre-emptive diagnosis was neoplasia in 13 patients (21.7%). The biopsy was percutaneous in 9 patients (15%) and incisional in 7 patients (11.7%). Histological analysis was achieved in 35 cases (57%). Surgical excision was the first line treatment in 46.7% of patients, and non-surgical in the remaining patients. The follow-up strategy was clinical in 16 patients (26.7%) or based on imaging investigation in 23 patients (38.3%).
UNASSIGNED: Although MO in children is described as a rare pathology, identifying the benignity of the condition is essential to avoid unnecessary invasive treatment and to avoid delaying the treatment of a potentially life-threatening entity. It seems that there is no consensus established concerning the proper imaging for diagnosis. Clinicians should acknowledge that the absence of a triggering trauma tends to direct the investigation and the management toward a surgical attitude. Conservative management is key, however, surgical excision can be proposed on matured lesions on a case-by-case basis. The absence of recurrence is not excluded. Therefore, a close clinical follow-up is suggested for all cases. The true benefit of a radiological is questioned in a question known to be self-resolving.

Myositis ossificans (MO) is a benign, self-limiting, and nonneoplastic lesion involving the skeletal muscle or soft tissue, rarely occurring in the head and neck. It is relatively rare in clinical practice, and it is difficult to distinguish specific cases from musculoskeletal conditions, which poses unique challenges for clinical diagnosis and treatment. We reported that a 9-year-old boy suffered from local and nontraumatic MO of the trapezius muscle. Given the rarity of this case, the present article detailed the diagnosis and treatment of this rare case and reviewed the relevant literature on MO, focusing on the clinical, pathological, and radiographic characteristics of MO. Notably, these investigations aimed to enhance clinicians\' understanding of the disease and improve diagnostic accuracy.

BACKGROUND: Progressive osseous heteroplasia (POH) is a rare genetic condition that causes progressive ossification. This usually results from an inactivating mutation of the paternal GNAS gene. Herein, we report a case of POH caused by a novel mutation in exon 2 of the GNAS gene.
METHODS: A 5-year-old Chinese boy was referred to our hospital for a growing mass in his right foot. Although laboratory findings were normal, radiographic imaging revealed severe ossification in his right foot and smaller areas of intramuscular ossification in his arms and legs. A de novo mutation (c.175C > T, p.Q59X) in exon 2 of the GNAS gene was identified, prompting a diagnosis of POH. We conducted a systematic literature review to better understand this rare disease.
CONCLUSIONS: We have discovered that a de novo nonsense mutation in exon 2 of GNAS can lead to POH. Our literature review revealed that ankylosis of the extremities is the primary clinical outcome in patients with POH. Unlike other conditions such as fibrodysplasia ossificans progressiva (FOP), patients with POH do not experience respiratory failure. However, much remains to be learned about the relationship between the type of GNAS gene mutation and the resulting POH symptoms. Further research is needed to understand this complex and rare disease. This case adds to our current understanding of POH and will contribute to future studies and treatments.

Extra-skeletal osteosarcoma is a rare malignant soft tissue sarcoma which can cause a diagnostic challenge due to its non-specific presentation and soft tissue mineralisation, thus potentially mimicking conditions such as myositis ossificans. This review will outline the demographics, clinical presentation, key imaging features, differential diagnosis, management and outcomes of extra-skeletal osteosarcoma and serve as a reference to radiologists and other clinicians involved in the care of patients with soft tissue tumours and tumour-like lesions.

BACKGROUND: Heterotopic ossification (HO) is the formation of bone in soft tissue resultant from inflammatory processes. Lesion formation after arthroscopic procedures is an uncommon but challenging complication. Optimal prophylaxis and management strategies have not been clearly defined.
OBJECTIVE: To present a scoping review of the pathophysiology, risk factors, diagnostic modalities, prophylaxis recommendations, and current treatment practices concerning HO after arthroscopic management of orthopaedic injuries.
METHODS: Scoping review; Level of evidence, 4.
METHODS: A scoping review via a PubMed search was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) guidelines. The search strategy was based on the terms \"heterotopic ossification\" AND \"arthroscopy.\" The clinical outcomes review included studies on the arthroscopic management of orthopaedic injuries in which the primary subject matter or a secondary outcome was the development of HO. An analysis of the pathophysiology, diagnostic modalities, and management options was reported.
RESULTS: A total of 43 studies (33,065 patients) reported on HO after hip arthroscopy, while 21 (83 patients) collectively reported on HO after arthroscopic procedures to the shoulder, elbow, knee, or ankle; however, management techniques were not standardized. Identified risk factors for HO included male sex and mixed impingement pathology, while intraoperative capsular management was not suggested as a contributing factor. Diagnosis of ossification foci was performed using radiography and computed tomography. The rate of HO after hip arthroscopy procedures approached 46% without prophylaxis, and administration of nonsteroidal anti-inflammatory drugs (NSAIDs) decreased occurrence rates to 4% but carries associated risks. External beam radiation has not been exclusively studied for use after arthroscopic procedures.
CONCLUSIONS: HO is a known complication after arthroscopic management of orthopaedic injuries. NSAID prophylaxis has been demonstrated to be effective after hip arthroscopy procedures. Patients with persistent symptoms and mature lesions may be indicated for surgical excision, although variability is present in patient-reported outcome scores postoperatively.

UNASSIGNED: Myositis ossificans traumatica (MOT) is a self-limiting and self-resolving pathology. In most cases, conservative treatment is chosen as the first step. Surgical treatment is reserved for cases of failure of conservative treatment with persistence of pain and mass. The case presented concerns an 18-year-old soccer player suffering from bilateral adductor longus (AL) MOT results following two different sports injuries. The patient reports the appearance of swelling and palpable mass at the proximal and medial region of the thigh, about 2 cm from the pubic symphysis, along the course of the adductor magnus. The radiological investigation showed the presence of a calcification along the course of the right and left AL muscles. Surgical treatment was considered for the right thigh injury, being symptomatic 1 year after the onset and refractory to other treatments. At 3 months of follow-up, the patient was asymptomatic and completed the rehabilitation program for the recovery of muscle strength and range of motion (ROM). In cases where MOT manifests with resistant pain, ROM restriction and daily activity reduction, surgical excision is the preferred option.

Traumatic myositis ossificans (MO) circumscripta is an uncommon nonhereditary pathophysiological result of muscular trauma that is detected by radiographic imaging three to four weeks following initial trauma. It is responsible for great global morbidity, with symptoms of prolonged pain, diminished flexibility, and stiffness. There is frequently a delay in diagnosis due to the generalized symptoms and varying radiographic presentation. The goal of therapy is to rule out serious complications (such as soft tissue sarcoma) and to restore strength and range of motion (ROM) as soon as possible. Here we detail the case of a 32-year-old male with a delayed diagnosis of MO who presented to the hospital with left lower extremity pain and swelling following a motor vehicle accident (MVA) that occurred one month prior.

Myositis ossificans (MO) is a rare, benign ossifying lesion characterized by focal formation of heterotopic bone and cartilage in extraskeletal soft-tissue that most commonly occurs in young adults. In most cases, no causative factor can be identified. The diagnosis of MO is usually based on the patient\'s history of trauma, clinical signs, on imaging appearance and histological examination. We present a non-traumatic MO case of the forearm in a 40-year-old man with weakness in left finger motion, a decrease in prehension for more than three weeks, without any weight loss, malaise, anorexia or fever. The clinical symptoms and radiological findings can be easily confused with malignant lesions. Treatment is usually conservative but, due to the limited strength and range of motion of the left hand, the tumor was extirpated and the diagnosis of MO was made by biopsy. The patient had no neurological deficits after surgical treatment and was discharged on the fifth day after the surgery in good condition with the recommendation to begin a rehabilitation program.