[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.