[Musculoskeletal manifestations of sarcoidosis]

Musculoskeletal manifestations in the context of sarcoidosis are frequently observed. The rheumatologist regularly encounters this disease in clinical practice. In the present review, we aim to give a current overview of the manifestations and treatments relevant to the practicing rheumatologist. The most frequently encountered manifestation is Lofgren's syndrome, which is characterized by bilateral ankle periarthritis, bilateral hilar lymphadenopathy, and erythema nodosum and has an excellent prognosis. Chronic arthropathy most commonly manifests as oligoarthritis, which sometimes hampers its differentiation from spondylarthropathies, especially when sacroiliitis, enthesitis or dactylitis are simultaneously present. Isolated vertebral granulomas are rare and require infectious and malignant disorders to be excluded, since there are no specific imaging findings that are exclusively found in vertebral sarcoidosis. The presence of granulomas in skeletal muscle is common in muscle biopsies, whereas clinically overt myopathy is present in only around 1-2% of patients. Therapeutic responses vary among the different clinical phenotypes. Non-steroidal anti-inflammatory drugs and low to medium dose glucocorticoids are the first-line therapy for musculoskeletal manifestations and often lead to adequate disease control in acute sarcoidosis. When these are ineffective or not tolerated, steroid-sparing agents are increasingly used in chronic sarcoidosis. Evidence for all medications used in sarcoid-related arthritis is comparatively scant. When supplementing vitamin D, the possible development of hypercalcemia, even at standard doses, needs to be considered; the optimal therapeutic levels for the prevention of medication-induced osteoporosis in sarcoidosis have not been firmly established.