Possible differential diagnosis of unilateral SCG swelling
Mechanical enthesopathy - Overload syndromes - Trauma
Inflammatory enthesitis - Peripheral spondyloarthritides (e.g. psoriatic arthritis, SAPHO syndrome, reactive arthritis) - Endocrinopathies (e.g. diabetes, hypothyroidism) - Crystalline arthropathies (e.g. gout, CPPD)
Arthritis - Septic - Inflammatory rheumatic diseases (e.g. rheumatoid arthritis, peripheral spondyloarthritis) - Crystalline arthritis (e.g. gout, CPPD)
Osteitis/ Osteomyelitis - Septic - Aseptic (e.g. SAPHO syndrome, CRMO) - Osteitis clavicularis condensans
Subluxation - Traumatic with ligamentous lesions - Benign subluxation (mainly women, dominant side) - Articular hyperlaxity
Arthrosis - primary (rare) - secondary (for all other mentioned diseases), with or without subluxation
Sketch of the sternoclavicular joint
The SC is a mobile and poorly congruent joint in the inferior-medial part (discoclavicular compartment, zone B), where subluxations occur and degenerative changes (arthrosis) develop. In the cranial part (zone A), there is a strongly vascularised area with fibrocartilage; septic arthritis occurs most frequently here.
Reference:
Tamborrini G, Gut C, Schaefer DJ, Lardinois D. CME-Rheumatologie 11/Auflösung: Sternoclaviculäre Schwellung – immer ein Tietze-Syndrom? Praxis (Bern 1994). 2017;106(7):387-389. German. doi: 10.1024/1661-8157/a002637. PMID: 28357905.