[Skeletal sarcoidosis].

OBJECTIVE: Presentation of the etiology, pathology, clinical course, radiology and differential diagnostics of skeletal sarcoidosis. PATHOANATOMICAL PRINCIPLES: Noncaseating epithelioid cell granulomas can trigger solitary, multiple or disseminated osteolysis, reactive osteosclerosis and/or granulomatous synovitis. INCIDENCE: The incidence of sarcoidosis is 10-12 per 100,000 inhabitants per year. Skeletal involvement is approximately 14 %. CLINICAL ASPECTS: Skeletal involvement occurs almost exclusively in the stage of lymph node and pulmonary manifestation. Most cases of skeletal involvement are clinically asymptomatic. In the case of synovial involvement, unspecific joint complaints (arthralgia) or less commonly arthritis can occur. Typical skin alterations can be diagnostically significant. RADIOLOGY: Punch out lesions osteolysis, coarse destruction and osteosclerosis can occur, which are best visualized with projection radiography and/or computed tomography. Pure bone marrow foci without interaction with the bone can only be detected with magnetic resonance imaging (MRI) and more recently with positron emission tomography (PET), mostly as incidental findings. There is a predeliction for the hand and trunk skeleton. DIFFERENTIAL DIAGNOSTICS: Skeletal tuberculosis, metastases, multiple myeloma, Langerhans cell histiocytosis and sarcoid-like reactions in solid tumors must be differentiated. The key factors for correct diagnosis are thorax radiography, thorax CT and dermatological manifestations.