C40-30 Treatment-Associated Renal Impairment in a Patient With Multisystem Sarcoidosis

Abstract Introduction Sarcoidosis is a systemic granulomatous disease of unclear etiology that can involve nearly any organ, though pulmonary involvement is most common. Renal and neurologic manifestations are less frequent but can be clinically significant, especially in patients with complex and overlapping treatment related toxicities. Timely diagnosis and careful therapeutic choices are crucial in such cases. Case Report A 61-year-old man presented with acute appendicitis. Abdominal imaging incidentally revealed pulmonary nodules and lymphadenopathy, raising concern for systemic disease. Chest CT and endobronchial biopsy revealed a diagnosis of pulmonary sarcoidosis. The patient had a history of autoimmune endocrine dysfunction and chronic inflammatory demyelinating polyneuropathy (CIDP), previously managed with IVIG and mycophenolate mofetil. Following the sarcoidosis diagnosis, new-onset renal dysfunction developed. Renal biopsy demonstrated immunoglobulin deposition without granulomas, suggesting IVIG-associated nephropathy rather than direct sarcoid involvement. Brain MRI revealed demyelinating changes consistent with neurosarcoidosis, however lumbar puncture was not obtained. Given concerns for treatment-related renal injury, IVIG was discontinued and methotrexate initiated. The patient remained clinically stable under multidisciplinary monitoring. Discussion This case illustrates the complexity of managing multisystem sarcoidosis complicated by treatment-related toxicity. Although renal sarcoidosis often presents with granulomatous interstitial nephritis, this patient’s biopsy revealed immunoglobulin deposition without granulomas, suggesting IVIG-associated nephropathy. Given that he was already on immunosuppressive therapy likely adequate for renal sarcoid, disease progression would be unlikely if sarcoidosis were the cause. However, the patient had ongoing neurologic symptoms concerning for neurosarcoidosis versus a previous diagnosis of chronic inflammatory demyelinating polyneuropathy. IVIG, although previously effective for his neurologic symptoms, was contraindicated due to renal toxicity and mycophenolate may be suboptimal for neurologic disease. While methotrexate may offer broader systemic efficacy, it may not offer the renal benefits of mycophenolate. TNF-α inhibitors such as infliximab may offer more robust neurologic control but carry significant risk. With minimal pulmonary symptoms and presumed non-sarcoid renal disease, the challenge lies in selecting a regimen that sufficiently addresses neurologic involvement while minimizing further renal injury and overall immunosuppressive burden. Conclusion This case is notable for discovery of multisystem sarcoidosis further complicated by treatment-related renal injury. It highlights the need for individualized management and vigilance for iatrogenic harm in complex sarcoidosis presentations. This abstract is funded by: None