Muscle wasting & weakness: A rarepresentation of sarcoidosis

Background/AimsSarcoidosis is a rare multisystem disease characterised by thepresence of noncaseating granulomas. It most commonly affects thelungs though can affect any other organ system. Rarely, it can manifestas an acute myopathy. We describe a case of a patient presenting withmuscle weakness and constitutional symptoms who was eventuallydiagnosed with sarcoidosis.MethodsA 48-year-old male with a background of lumbar spondylosis andBPH, presented with a 6-week history of progressive upper and lowerlimb weakness, myalgia and reduced mobility. He also described an18-month history of progressive fatigue, drenching night sweats and 10-kilogram weight loss. His symptoms meant he was unable to workas a firefighter. Examination demonstrated profound muscle wastingand reduced power in the proximal muscles of his upper and lowerlimbs. There was no evidence of rash, synovitis or lymphadenopathy.Blood tests showed a normocytic anaemia (Hb 100 g/L) and raised Creactive peptide (180 mg/L) and erythrocyte sedimentation rate(100 mm/hour). The creatine kinase ranged between 20-42 units/litre.He had a weakly positive anti-nuclear antibody (1:80). The remainingautoantibody screen was negative including ENA, DSDNA, ANCA, rheumatoid factor and anti-CCP. Complement proteins were unremarkable. Furthermore, an extended myositis panel revealed nomyositis-specific or myositis-associated antibodies. Serum calciumand angiotensin-converting enzyme (ACE) levels were normal. Bloodcultures and virology screen including for HIV, hepatitis B, hepatitis C, CMV, EBV, COVID-19 and respiratory viruses were all negative. Achest radiograph was also unremarkable.ResultsHe subsequently underwent electromyography which revealed generalised myopathy. An MRI of the lower limb proximal musculatureshowed evidence of muscle oedema worse on the right-side but nodefinitive evidence of myositis. A PET-CT followed revealing FDG-avidgeneralised lymphadenopathy and polyarticular uptake, but littleuptake in the skeletal muscles. He underwent an external iliac lymphnode core biopsy which demonstrated multiple noncaseating granulomas and lymphadenitis. Cultures for Tuberculosis were negative andthere was no evidence of a lymphoproliferative disorder. A musclebiopsy was desired but not possible due to lack of availability becauseof the COVID-19 pandemic. The patient was diagnosed withsarcoidosis and commenced on three pulses of intravenous methylprednisolone followed by a weaning regimen of high-dose oralprednisolone and subcutaneous methotrexate. This resulted in asustained improvement in his symptoms and normalisation ofinflammatory markers.ConclusionSymptomatic myopathy is present in only 0.5-2.5% of sarcoidosispatients. This unique case highlights the heterogeneity of this diseaseand the vital role different diagnostic modalities play in achieving thecorrect diagnosis. It is also pertinent that the lymphadenopathy, foundincidentally via imaging, led to the diagnosis. Although notoriously adiagnosis of exclusion, this case emphasises the importance ofconsidering sarcoidosis even in the absence of respiratory symptoms, a raised ACE or hypercalcaemia.