The swollen sternoclavicular joint- A diagnostic dilemma

Clinical History

Three patients presented with symptoms associated with sternoclavicular joint pathology. The SCJ is involved in a variety of conditions. Imaging has a vital role in solving a challenging diagnostic dilemma.

Imaging Findings

Three patients presented with sternoclavicular joint arthropathy. Cases 1 and 2, a 60-year-old female and 51-year-old male, respectively, had unilateral SCJ involvement. Case 3 deals with, a 68-year-old female, who had bilateral SCJ involvement. Inflammatory markers were found to be marginally raised, with white cell counts being within normal limits in all cases. The patient was not suggested to undergone bone scans. Plain radiographs taken of the SCJs proved to be difficult to interpret, and further imaging with CT was performed. An ultrasound scan demonstrated soft tissue thickening around the joint, and a power-Doppler scan confirmed prominent neovascularity within the periarticular soft tissue, suggesting active synovitis. The CT proved to be the most informative imaging tool. Unenhanced thin (1mm) sections were obtained through the SCJs with coronal reformats. The affected joints were found to be encased by thickened periarticular soft tissue, the joint space was found to be reduced, and bone erosions/subchondral cysts could be seen on both the clavicular and the sternal portions of the joint. The periarticular formation of new bone was present, and in Case 2, hyperostosis was detected, which involved the medial aspect of the right clavicle. The distal clavicle had subluxed anteriorly in Cases 1 and 3, and superiorly in Case 2. Biopsies from the SCJ were obtained using CT guidance in Cases 1 and 3. The samples were reported as being “non-specific inflammatory tissue”, but the report excluded neoplasia, and the culture was reported to be negative. MR imaging was performed in Case 2, and it demonstrated bone marrow oedema on both sides of the joint space and a joint effusion. The florid enhancement of the periarticular soft tissue following Gadolinium administration, confirmed the presence of synovitis.

Discussion

The SC joint is a synovial, diarthrodial joint between the medial end of the clavicle and the sternum. The two bone ends are covered with fibrocartilage and separated by a disc. There is a capsule around the joint, which is strengthened by a number of ligaments. The SCJ is a highly mobile joint, moving with respiration and the scapulohumeral complex. The occurrence of SCJ arthropathy is not uncommon and the patients may present with pain in the anterior chest wall, shoulder or neck, but a pressure on the joint usually replicates the spontaneous pain [1]. Many disease entities can affect the SCJ including psoriasis and other seronegative spondyloarthropathies, rheumatoid arthritis, degenerative joint disease, infection, trauma and malignancy. The rich supply of entheses around the SCJ may explain why it is a common target for spondyloarthropathies [1]. The nosology of the spondyloarthropathies involving the SCJ is confusing and controversial [2], and they should be considered as a spectrum of disease with overlapping clinical and radiological features. Included in this spectrum, are the SAPHO syndrome and chronic recurrent multifocal osteitis (CRMO) [2, 3]. It is not possible to determine the aetiology based on morphological features alone. Histology and a culture of the joint aspirate may not be helpful, and there is no reliable serological assay which can distinguish the spondyloarthropathies from other causes of SCJ arthropathy. Imaging plays a vital role in excluding potentially treatable conditions. The overlying structures of the thorax mean that plain radiography is limited in the evaluation of sternoclavicular joint disease. An ultrasound scan will show a joint effusion and the power-Doppler scan will establish the presence of synovitis. Bone scintigraphy can assess the extent and intensity of the disease, and CT/MR procedures may demonstrate erosions and help to differentiate inflammatory arthropathy from osteomyelitis. MR provides information about the bone marrow, joint effusion and synovitis. A CT provides good bone and soft tissue detail, which can be displayed in multiplanar reformats. It is also the modality of choice to perform a guided biopsy of the joint. Typical degenerative changes such as subchondral sclerosis, unevenness of the articular surface and presence of osteophytes in the SCJ are seen in 50% of people over the age of 60 [4]. The subluxation of the medial end of the clavicle can also occur in degenerative joint disease, and is thought to be due to ligament damage [1]. Therefore, degenerative and inflammatory changes may coexist. The inflammatory changes include the presence of clavicular and sternal subchondral cysts/erosions with or without a sclerotic rim, depending on the aggressiveness of the process [4]. The considerable overlap in the appearances of the disease entities affecting the SCJ makes it difficult to diagnose the pathology based on morphological features alone. Therefore, a clinical approach is important in the diagnosis of SCJ arthropathy [2]. In the case of an acute onset, inflammatory causes and septic arthritis should be considered. It is particularly important to exclude the possibility of TB, which may present as chronic SCJ arthropathy. The main role of the radiologist is to exclude infection and malignancy, best achieved by a CT-guided biopsy. This done, the term “inflammatory arthropathy” should be preferably be used while attempting to specify a particular anterior chest wall syndrome.

Differential Diagnosis List

Final Diagnosis

Sternoclavicular joint inflammatory arthropathy.

URL:	https://www.eurorad.org/case/3424
DOI:	10.1594/EURORAD/CASE.3424
ISSN:	1563-4086