Sarcoidosis With Muscular and Peripheral Nervous System Involvement: An Atypical Presentation of a Rare Disease

Neuromuscular sarcoidosis is uncommon and may represent a diagnostic challenge, particularly in the absence of more typical sarcoidosis manifestations such as pulmonary involvement. We report a case of a 71-year-old male presenting with constitutional symptoms, weight loss, progressive gait impairment, hypercalcemia, and acute kidney injury. Initial evaluation excluded malignancy, active infection, and monoclonal gammopathy. Advanced imaging showed diffuse muscular involvement, and muscle biopsy confirmed non-caseating granulomatous myositis, establishing the diagnosis of muscular sarcoidosis. The patient improved with corticosteroid therapy but developed sensory axonal polyneuropathy during tapering, requiring steroid-sparing immunosuppression with azathioprine. This case highlights the need to consider sarcoidosis in unexplained systemic and neuromuscular syndromes, even in the absence of pulmonary or other common extrapulmonary manifestations.