Synovial osteochondromatosis mimicking juvenile idiopathic arthritis in an adolescent: a case-based review

Bilateral Knee Synovial Chondromatosis in a 2-Year-Old Girl: First Reported Case and Literature Review

BACKGROUND Synovial chondromatosis (SC) is a rare monoarticular benign condition characterized by the development of intra- or periarticular cartilage-like nodules or loose bodies. Typically affecting middle-aged men, SC is exceptionally rare in female pediatric patients. Symptoms include diffuse pain, swelling, and limited joint movement. The loose bodies are typically numerous, small, rounded, and uniform in size. Histologically, they consist of hyaline cartilage-like nodules containing clusters of chondrocytes. Bilateral SC in the knee of young children is even rarer and has not been previously documented in the medical literature. CASE REPORT A 2-year-old girl presented with recent pain in her right knee without preceding trauma. Physical examination revealed joint effusion, a limping gait, and limited knee flexion, with no signs of local inflammation. Radiographs showed normal joint structures, and laboratory test results, except for an elevated CRP, were normal. Joint aspiration ruled out septic arthritis. The worsening of symptoms within a relatively short period prompted further investigation, leading to the identification of numerous cartilaginous nodules within the joint during exploratory arthrotomy. Microscopic examination revealed unossified cartilage-like nodules containing disorganized chondrocytes. Four months after surgery, she was diagnosed with SC in the contralateral knee. CONCLUSIONS Given the rarity of synovial chondromatosis in young children, and the even rarer bilateral presentation in a large joint, this case report provides an opportunity to explore the challenges in diagnosing and managing such conditions in pediatric patients. To the best of our knowledge, this is the youngest reported case of bilateral SC of the knee in a pediatric patient.

[Synovial chondromatosis : Results from the histopathological arthritis register of the German Society for Orthopedic Rheumatology]

BACKGROUND

Synovial chondromatosis, or osteochondromatosis, is a rare benign disorder that occurs in joints, tendon sheaths, or bursae, characterized by cartilage proliferations of varying sizes and shapes, often with ossifications. In this study the prevalence, sensitivity, gender predominance, differential diagnoses, and primary localization of synovial chondromatosis are analyzed within the Histopathological Arthritis Registry of the German Society for Orthopedic Rheumatology.

METHODS

All cases of patients diagnosed with "synovial chondromatosis" from the Histopathological Arthritis Registry of the German Society for Orthopedic Rheumatology were retrospectively examined, covering the period from 1 January 2018, to 31 December 2022.

RESULTS

Between 1 January 2018, and 31 December 2022, there were 14 cases of synovial chondromatosis out of a total of 13,222 cases in the Histopathological Arthritis Register of the German Society for Orthopedic Rheumatology. The available data include primary localization, and age and gender of the patients. Among the 13,222 cases in the Histopathological Arthritis Register of the German Society for Orthopedic Rheumatology, 14 were histopathologically confirmed as synovial chondromatosis. This resulted in a prevalence of 0.1% or 1.13 per 1,000 cases. The correct clinical presumptive diagnosis was made in 5 cases, yielding a sensitivity of 35.7%, 95% confidence interval (CI) 12.8% to 64.9%.

DISCUSSION

Differential diagnoses for this condition include pigmented villonodular synovitis, tenosynovial giant cell tumor, and chondrosarcoma. Synovial chondromatosis frequently occurs in large joints such as the knee, hip, and the temporomandibular joint. A peak incidence is described in the fifth decade of life. However, the disorder can also occur in children. For the first time, the study was able to provide data for Germany based on a large sample. Additionally, initial statements regarding the prevalence and sensitivity of synovial chondromatosis could be made. The aim of this work is to raise awareness of this very rare disease to enable faster and more efficient diagnosis. The study also highlights the importance of histopathology in the diagnosis of synovial chondromatosis.

Pediatric Synovial Osteochondromatosis of the Knee with Leg Length Discrepancy: A Case Report

Introduction

Synovial chondromatosis (SC) is very rare among children. We are aware of no reports of patients with SC accompanied by leg length discrepancy (LLD).

Case Report

We describe a case of synovial osteochondromatosis of a 7-year-old boy complicated by LLD. We performed epiphysiodesis of the distal femur and arthroscopic resection of loose bodies and total synovectomy. Three years after surgery, LLD had been corrected and there was no sign of recurrence.

Conclusion

Physicians should be aware of synovial osteochondromatosis complicated by LLD in childhood and take radiographs of the whole length of lower legs when this condition is suspected.

Chronic limping in childhood, what else other than juvenile idiopathic arthritis: a case series

BACKGROUND

Limping is a common clinical symptom in childhood; different clinical conditions may lead to limping and the diagnosis of the underlying cause may often be a challenge for the pediatrician.

CASE PRESENTATION

We describe the clinical manifestations, radiological pictures and disease course of other causes of limping in childhood, through a case series of seven cases and a brief discussion of each disease.

CONCLUSIONS

although trauma is the most common cause of acute limping, when there is no history of traumatic events and the limping has a chronic course, Juvenile Idiopathic Arthritis is usually the most likely clinical diagnosis. However, other some rare conditions should be taken into account if JIA is not confirmed or if it presents with atypical clinical picture.

Monoarticular juvenile idiopathic arthritis as a distinct clinical entity A proof-of-concept study

BACKGROUND

Currently, monoarticular Juvenile Idiopathic Arthritis (monoJIA) is included in the ILAR classification as oligoarticular subtype although various aspects, from clinical practice, suggest it as a separate entity.

OBJECTIVES

To describe the clinical characteristics of persistent monoJIA.

METHODS

Patients with oligoJIA and with at least two years follow-up entered the study. Those with monoarticular onset and persistent monoarticular course were compared with those with oligoJIA. Variables considered were: sex, age at onset, presence of benign joint hypermobility (BJH), ANA, uveitis, therapy and outcome. Patients who had not undergone clinical follow-up for more than 12 months were contacted by structured telephone interview.

RESULTS

Of 347 patients with oligoJIA, 196 with monoarticular onset entered the study and 118 (60.2%), identified as persistent monoJIA, were compared with 229 oligoJIA. The mean follow-up was 11.4 years. The switch from monoarticular onset to oligoarticular course of 78 patients (38.8%) occurred by the first three years from onset. In comparison with oligoJIA, the most significant features of monoJIA were later age at onset (6.1 vs. 4.7 years), lower female prevalence (70.3 vs. 83.4%), higher frequency of BJH (61.9 vs. 46.3%), lower frequency of uveitis (14.4 vs. 34.1%) and ANA+ (68.6 vs. 89.5%) and better long-term outcome.

CONCLUSIONS

MonoJIA, defined as persistent arthritis of unknown origin of a single joint for at least three years, seems to be a separate clinical entity from oligoJIA. This evidence may be taken into consideration for its possible inclusion into the new classification criteria for JIA and open new therapeutic perspectives.