Background: Sternocostoclavicular hyperostosis (SCCH) is a rare inflammatory disorder of the axial skeleton of unclear aetiology, characterized by chronic sterile osteomyelitis predominantly involving the sternum, medial end of the clavicles and upper ribs. Familial clustering suggests a genetic predisposition. Typical skin lesions of palmoplantar pustulosis (PPP) are prevalent and other skin, joint and gut manifestations are relatively frequently reported, suggesting a possible autoimmune contribution to the pathogenesis of the disorder. The objective was to determine whether autoimmune diseases are prevalent in SCCH patients and their first degree relatives.
Methods: Patients with an established SCCH diagnosis followed up at our Out-patient Clinic and/or members of the Dutch SCCH Patients Association. Systematic telephone interviews were conducted in SCCH patients. Annotated pedigrees were constructed. Enquiries mainly concerned any diagnosed autoimmune disease in patients as well as their first degree relatives (parents, siblings and children). Diagnoses were wherever possible verified from patients hospital records.
Results: Seventy-three patients (86% female, aged 18-80 years, median age 58 years) from 65 families were available for interview, out of approximately 92 known patients. Information about 527 unaffected first degree relatives (52.4% female) was documented; 13 patients (18%) had at least one other SCCH patient among their relatives. 20 patients (27%) and 47 relatives (8.9%) had a well-documented autoimmune disease. The prevalence of autoimmune disease increased to 55% (40/73) in SCCH patients, and to 10.4% (55/527) in relatives, by including PPP as putative autoimmune disease. None of the patients reported a diagnosis of inflammatory bowel disease.
Conclusions: Our data suggest that the prevalence of autoimmune disease is high in patients with SCCH and their first degree relatives. This finding warrants further investigation of the role of autoimmunity in the pathophysiology of the intriguing aberrant response of bone to inflammation observed in SCCH.
Disclosure: The authors declared no competing interests.