Sarcoidosis is a systemic granulomatous disorder of unknown etiology characterized by non-caseating epithelioid granulomas affecting any organ system. While pulmonary disease and hilar lymphadenopathy occur in over 90% of patients, extrapulmonary manifestations are common and may dominate the clinical picture in up to 30% of cases. Extrapulmonary sarcoidosis carries higher morbidity than isolated pulmonary disease and may require systemic immunosuppression even when lung disease is mild.
Cardiac sarcoidosis affects 5-25% clinically and up to 25% subclinically, manifesting with conduction abnormalities (especially AV block), ventricular arrhythmias, heart failure, and sudden cardiac death. Ocular involvement (25-50%) ranges from anterior uveitis (most common) to posterior uveitis, retinal vasculitis, and optic neuropathy, with risk of permanent visual loss. Neurosarcoidosis (5-10%) presents with cranial neuropathies (especially facial nerve), meningitis, hypothalamic-pituitary dysfunction, and parenchymal CNS lesions. Cutaneous lesions include erythema nodosum, lupus pernio, plaques, and subcutaneous nodules. Hepatic granulomas are common but rarely cause significant dysfunction; renal involvement may produce hypercalcemia, nephrocalcinosis, and granulomatous interstitial nephritis. Musculoskeletal manifestations include arthralgia, myopathy, and bone lesions.
Surveillance for extrapulmonary involvement requires baseline assessment in all sarcoidosis patients: 12-lead EKG and echocardiography (with cardiac MRI or FDG-PET if cardiac symptoms or abnormal screening), comprehensive ophthalmologic examination including slit lamp and dilated fundoscopy at diagnosis and annually, neurologic examination with brain MRI if symptomatic, calcium and vitamin D monitoring, liver function tests, urinalysis and renal function, and skin examination. Treatment of extrapulmonary disease often requires more aggressive immunosuppression than pulmonary disease alone: corticosteroids remain first-line, with methotrexate, azathioprine, mycophenolate, and TNF-alpha inhibitors (infliximab) for refractory or severe disease. Cardiac sarcoidosis often requires implantable cardioverter-defibrillator and may need heart transplantation. Multidisciplinary follow-up is essential for organ-specific complications and treatment side effects.