C40-17 A Challenging Case of Sarcoidosis-Associated Small Fiber Neuropathy Responsive to IVIG

Abstract Introduction There are no established treatment guidelines for sarcoidosis-associated small fiber neuropathy (SSFN), which affects 40-60% of sarcoidosis patients (1). We present a case of systemic sarcoidosis with refractory dysautonomic symptoms unresponsive to anti-Tumor Necrosis Factor (anti-TNF) therapy that responded to Intravenous immunoglobulin (IVIG). Case Presentation A 61-year-old female with relevant past medical history of seronegative rheumatoid arthritis, autoimmune hepatitis, erythema nodosum, atrial fibrillation, and thoracic aortic aneurysm was referred to interventional pulmonology for progressive mediastinal and hilar lymphadenopathy on CT (Figure 1). She reported 50 pounds of unintentional weight loss, fatigue, dyspnea, chest pain, arthralgias, myalgias, paresthesias, arrhythmias, hypotension, and diaphoresis. Endobronchial ultrasound-guided lymph node biopsies demonstrated noncaseating microgranulomas, consistent with systemic sarcoidosis. High-dose prednisone (60 mg daily) transiently improved symptoms, but due to recurrence on tapering, rheumatology introduced methotrexate and gabapentin. Dyspnea improved, but dysautonomic symptoms (chronic pain, labile blood pressures, temperature swings) persisted, despite addition of maximal-dose duloxetine. She was subsequently hospitalized for chest pain, hypotension, and syncope. Workup revealed a newly reduced ejection fraction of 25-29%, prompting corticosteroid reinitiation and implantable cardioverter-defibrillator placement for suspected cardiac sarcoidosis. Methotrexate was uptitrated, and infliximab initiated although discontinued after two doses due to edema. Adalimumab was substituted. Despite steroid-induced fractures, tapering was limited by worsening dysautonomia. IVIG (1g/kg) was introduced, resulting in marked improvement. Both prednisone and gabapentin were successfully withdrawn over five months, and patient reported stable blood pressures, less pain, and no fevers while on maintenance IVIG, methotrexate, and adalimumab. Discussion This case demonstrates the difficulty in managing SSFN given that there is no standardized therapeutic protocol. In a large cohort study, symptomatic improvement was observed in 47/62 patients (76%) with SSFN treated with IVIG alone and 10/14 (71%) of patients treated with combination IVIG and anti-TNF therapy (2). The successful reduction in dysautonomic symptoms of SSFN with IVIG, in this patient, underscores the need for further investigation into its role in SSFN. Figure 1. Right hilar lymphadenopathy consistent with sarcoidosis. References: 1. Baughman RP, Valeyre D, Korsten P, et al. ERS clinical practice guidelines on treatment of sarcoidosis. Eur Respir J. 2021;58(6):2004079. Published 2021 Dec 16. doi:10.1183/13993003.04079-2020 2. Tavee JO, Karwa K, Ahmed Z, Thompson N, Parambil J, Culver DA. Sarcoidosis-associated small fiber neuropathy in a large cohort: Clinical aspects and response to IVIG and anti-TNF alpha treatment. Respir Med. 2017;126:135-138. doi:10.1016/j.rmed.2017.03.011 This abstract is funded by: None