EYES WIDE SHUT: AN UNUSUAL CAUSE OF PTOSIS

TOPIC: Lung Cancer TYPE: Medical Student/Resident Case Reports INTRODUCTION: Pembrolizumab is an immune checkpoint inhibitor (ICI) known to cause a variety of side effects. Here case lung cancer patient on pembrolizumab presented with dyspnea and chest pain was found have rare effect. CASE PRESENTATION: A 74-year-old female, stage IV adenocarcinoma the lung, hospital & shortness breath. She admitted fatigue, new-onset left-sided ptosis for 2 weeks RUE weakness. Patient day before her 3rd treatment. required supplemental O2 due hypoxia. Physical exam significant (L > R), UE weakness otherwise unremarkable. Labs were AKI, elevated CK CRP, borderline high leukocytosis. Imaging ruled out stroke PE. Her mass stable radiographically. Cardiac causes out. Despite initial treatment post-obstructive pneumonia, she remained symptomatic desaturated exertion, requiring non-invasive ventilation at times. Diaphragmatic paralysis, neuromuscular or paraneoplastic syndromes considered as possible etiologies. Serologies myasthenia gravis (MG), Lambert-Eaton myositis ordered. Hemi-diaphragmatic paralysis ABG showed evidence hypercapnia sitting supine spirometry demonstrated drop in FVC >20%, suggesting Anti-AChR Ab positive, while anti-MUSK Ab, anti-voltage-gated auto-antibodies all negative. diagnosed MG induced by pemrolizumab started prednisone, pyridostigmine IVIG. On follow-up, noted slow improvement chemotherapy hold steroid dose. DISCUSSION: Most ICI-induced (iciMG) cases from melanoma patients, it see them especially adenocarcinoma. iciMG can present exacerbation disease. The our patient's respiratory distress confounded post-obstruction pneumonia. There also uncertainty functioning diaphragm, which could result myositis. To differentiate two, Sekiguchi et al. recommended using ultrasound over needle EMG assess diaphragm dysfunction avoid pneumothorax. current recommendation treat plasmapheresis pulse-dose steroids. ICI trigger underlying autoimmune diseases. However, pre-existing conditions should not be contraindications therapy, there report tolerating re-challenge despite having iciMG. Thus, limiting therapeutic options based adverse events decided case-by-case basis. CONCLUSIONS: de novo gravis. These symptoms tend develop within first few cycles Physicians consider this differential when encountering similar patients. REFERENCE #1: Hibino M, Maeda K, Horiuchi S, Fukuda Kondo T. Pembrolizumab-induced cancer. Respirol Rep. 2018;6(7):e00355. Published 2018 Aug 7. doi:10.1002/rcr2.355 #2: Hashimoto R, Noda Y, Diaphragm involvement inhibitor-related Muscle Nerve. 2019;60(4):E23-E25. doi:10.1002/mus.26640 #3: Tedbirt B, De Pontville Branger P, Rechallenge after pembrolizumab-induced Eur J Cancer. 2019;113:72-74. doi:10.1016/j.ejca.2019.03.006 DISCLOSURES: No relevant relationships Rumon Chakravarty, source=Web Response Vernon Chan,