[Musculoskeletal manifestations of sarcoidosis]

[Sarcoidosis]

Sarcoidosis is the most common granulomatous disease in northern Europe. A distinction is made between acute forms of sarcoidosis and chronic sarcoidosis. Chronic sarcoidosis can affect practically all organs but the lungs are affected in 90-95% of patients. The clinical appearance varies between asymptomatic and oligosymptomatic courses, which are diagnosed more by chance, to courses with acute organ failure. An extensive organ work-up is necessary at the time of the initial diagnosis in order to record the extent of organ involvement and to make appropriate treatment decisions. Asymptomatic courses with purely pulmonary sarcoidosis do not require treatment and can be observed over the course of the disease, whereas courses with extensive organ involvement or organ dysfunction require treatment. The treatment consists primarily of the administration of glucocorticoids. If the effect of the glucocorticoids is insufficient or if there are side effects, various immunosuppressive agents, including biologics can be added.

Sarcoidosis and autoimmune diseases: differences, similarities and overlaps

PURPOSE OF REVIEW

Sarcoidosis is a rare, multisystem granulomatous disease of incompletely understood pathogenesis. Clinically, it shares common features with several systemic and organ-specific autoimmune diseases, although known autoantibodies or useful serologic markers for diagnosis and monitoring of disease activity are lacking. Sarcoidosis can both coexist with or mimic connective tissue diseases or vasculitis. Here, we review possible common etiologic factors between sarcoidosis and autoimmune disease, comparing clinical, laboratory and imaging features.

RECENT FINDINGS

Autoimmune diseases may precede or follow the diagnosis of sarcoidosis. Overall, the prevalence of both co-existing is unknown because of limited evidence. The presence of autoantibodies in sarcoidosis should raise suspicion of an underlying autoimmune disease that mimics or co-occurs with sarcoidosis. Silica dust exposure has been associated with an increased prevalence of both sarcoidosis and rheumatoid arthritis. In another study, autoimmune thyroid disease, Sjogren's syndrome and ankylosing spondylitis have been reported to be more frequent in sarcoidosis compared with healthy controls.

SUMMARY

A systematic diagnostic work-up is necessary to detect overlapping disease features in patients with sarcoidosis. Immune-modulating therapies need to be taken into account as these can induce paradoxical reactions.

Respiratory muscle involvement in sarcoidosis

INTRODUCTION

In sarcoidosis, muscle involvement is common, but mostly asymptomatic. Currently, little is known about respiratory muscle and diaphragm involvement and function in patients with sarcoidosis. Reduced inspiratory muscle strength and/or a reduced diaphragm function may contribute to exertional dyspnea, fatigue and reduced health-related quality of life. Previous studies using volitional and non-volitional tests demonstrated a reduced inspiratory muscle strength in sarcoidosis compared to control subjects, and also showed that respiratory muscle function may even be significantly impaired in a subset of patients. Areas covered: This review examines the evidence on respiratory muscle involvement and its implications in sarcoidosis with emphasis on pathogenesis, diagnosis and treatment of respiratory muscle dysfunction. The presented evidence was identified by a literature search performed in PubMed and Medline for articles about respiratory and skeletal muscle function in sarcoidosis through to January 2018. Expert commentary: Respiratory muscle involvement in sarcoidosis is an underdiagnosed condition, which may have an important impact on dyspnea and health-related quality of life. Further studies are needed to understand the etiology, pathogenesis and extent of respiratory muscle involvement in sarcoidosis.