Abstract Introduction – Sarcoidosis is a multisystem disorder of unknown etiology, primarily affecting the lungs and lymph nodes.1 Extrapulmonary manifestations, such as those involving the skin, muscles, and joints are also frequently observed.2,3 Small fiber neuropathy (SFN) is a common complication in patients with sarcoidosis.4 Currently, it is unknown whether neuropathic pain or the inflammatory component predominantly causes pain in the skin, muscles or joints in patients with sarcoidosisassociated SFN. Using our newly developed SFN phenotyping questionnaire (SFNPQ), we measured patient-reported symptoms at the level of skin, muscles and joints to assess the prevalence of these symptoms. Methods - First, the prevalence of granulomas, symptoms mentioned during consultations with neurologists and pulmonologists, and pain in the skin, muscles, or joints, indicated in the SFNPQ were investigated. Next, the prevalence of pain in specific body areas was analyzed for each organ and compared between healthy controls, patients with sarcoidosis with SFN, and those without SFN. Results - Patients reported more symptoms via the SFNPQ than during consultations, and symptoms in the skin, muscles, and joints were often not associated with granulomas in these organs. Cutaneous symptoms in the feet and muscular symptoms in the legs showed the highest prevalence in sarcoidosis-associated SFN (67% vs 77%, respectively). Additionally, joint symptoms were highly prevalent in patients with sarcoidosis, both with and without SFN. Conclusions - Cutaneous symptoms at the feet and muscular symptoms in the legs showed the highest prevalence patients with sarcoidosis. The SFNPQ was able to distinguish the characteristics and anatomical origins of SFN-related symptoms, providing valuable insights for future research and clinical practice. Introduction Sarcoidosis is a multisystem disorder of unknown etiology characterized by the formation of noncaseating granulomas, primarily affecting the lungs and lymph nodes.1 In addition, extrapulmonary manifestations are frequently described and can involve the skin, muscles and joints.2,3 Moreover, non-organ-specific symptoms such as fatigue, cognitive dysfunction and small fiber neuropathy (SFN) contribute to the morbidity associated with sarcoidosis.5 The skin is the second most affected organ in patients with sarcoidosis, with a prevalence ranging between 25-30%.6,7 Skin lesions can present as lupus pernio, macolupapular eruptions, and erythema nodosum.8 The clinical manifestation of sarcoid myopathy is very rare and remains asymptomatic in 50-80% of patients.9 Symptoms predominantly include muscle weakness or stiffness, depending on its presentation. Sarcoid myopathy can present as chronic myopathy, acute myositis, or nodular myopathy.3,9,10 The prevalence and presentation of joint complaints in patients with sarcoidosis can vary, with 10% presenting as acute inflammatory arthritis and up to 90% presenting as oligoarthritis.11 The inflammatory process may result in pain, swelling, stiffness or synovitis. SFN is a common complication in patients with sarcoidosis,4 with an estimated prevalence between 40-86%.12,13 Symptoms of SFN include burning pain, tingling and numbness, all of which can significantly impact health-related quality of life.14 Burning pain can be considered as cutaneous manifestation of SFN, while muscular pain has been described in small fiber neuropathy as part of a widespread pain phenotype.15 Although SFN may occur as a consequence of rheumatoid arthritis,16 arthralgia has not been described as specific symptom in patients with SFN. 4 70 4
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