Louisiana Via Research Day Book 2026

Case Studies: Section 2

Case Studies: Section 2

Binod Mehta; Jeni Kandel; Sai Diksha Vutukuru; Maria Akhtar; Coy Wayne Gammage St. Francis Medical Center, IM Residency 86 WHEN IMMUNOTHERAPY ATTACKS: A RARE CASE OF MYOSITIS AND MYASTHENIA GRAVIS OVERLAP SYNDROME

Jeni Kandel, MD; Dipesh Upreti, MD; Khawar Khurshid, MD; Navin Ramlal, MD St. Francis Medical Center, IM Residency Program 87 FROM COUGH TO CRISIS: EBV ASSOCIATED SEVERE THROMBOCYTOPENIA IN AN ELDERLY.

Background: Immune checkpoint inhibitor (ICI)- induced myositis and myasthenia gravis overlap syndrome is a rare immune-related adverse event (irAE). This syndrome involves immune mediated injury to both skeletal muscle and the neuromuscular junction, presenting clinically with symptoms such as ptosis, dysphagia, and generalized weakness. Unlike classic myasthenia gravis, autoantibodies are often negative, while anti-striational antibodies tend to be more frequently positive. Here, we present a rare case of pembrolizumab-associated myositis and myasthenia gravis overlap syndrome in an elderly patient. Report of Case: A 77-year-old man with a history of malignant melanoma on pembrolizumab presented with progressively worsening generalized weakness, myalgia, dysphagia with liquids, and shortness of breath for one week. Initial vital signs and laboratory workup were unremarkable. Neurological examination revealed proximal and distal limb weakness, bilateral ptosis, facial weakness, and hypoactive reflexes, with preserved sensation. He had received his first dose of pembrolizumab five weeks prior and his second dose one week

before admission. Additional testing, including AChR antibodies, anti-MuSK antibodies, and a paraneoplastic panel, was negative; however, anti-striational antibodies were positive. Given concern for an autoimmune etiology, he was empirically treated with a five-day course of IVIG, resulting in minimal improvement. Electromyography and nerve conduction studies revealed unstable, thin, and complex motor unit potentials, with normal repetitive nerve stimulation—findings consistent with probable myopathy and a neuromuscular transmission overlap disorder. In the context of recent pembrolizumab use, positive anti-striational antibodies, and EMG findings, the patient was diagnosed with an ICI-related irAE. He subsequently underwent five sessions of plasma exchange, after which he demonstrated marked improvement in muscle strength and respiratory function. Conclusion: This case underscores the diagnostic challenges of ICI-induced myositis and myasthenia gravis overlap syndrome, particularly when serological tests are inconclusive. As the use of ICIs continues to expand, clinicians must maintain a high index

of suspicion for these irAEs due to their high associated mortality.

Introduction: Epstein-Barr virus (EBV) is an uncommon but recognized cause of immune mediated thrombocytopenia, particularly in adults. This case report details the diagnostic and therapeutic complexities encountered in a 69-year-old female presenting with severe thrombocytopenia following a recent viral illness. Report of Case: The patient initially presented with upper respiratory symptoms, including low-grade fever, cough, and congestion, which progressed to fatigue and mild shortness of breath. Physical examination revealed no splenomegaly. Laboratory evaluation showed a critically low platelet count (<2,000/µL) with otherwise unremarkable findings. The patient had not started any new medications. Urgent management included platelet transfusion and high-dose prednisone, resulting in gradual improvement in platelet counts. Subsequent investigations revealed positive EBV serology (IgG > 600 U/mL and IgM 39.9 U/mL) and a bone marrow biopsy consistent with a reactive process, without evidence of malignancy. During hospitalization, the patient experienced a transfusion-related complication

contamination of platelets with gram-positive bacilli. She received empiric antibiotics, and blood cultures later showed no growth. The patient was discharged on a 14-day course of clindamycin following multidisciplinary input. Discussion: This case underscores the importance of considering viral etiologies, such as EBV, in adults presenting with severe isolated thrombocytopenia. It also highlights the risks associated with transfusion therapy, emphasizing the necessity for vigilance and multidisciplinary collaboration. Recognition of EBV as the underlying cause guided the therapeutic approach, particularly regarding the use and tapering of immunosuppressive therapy. Conclusion: EBV-induced thrombocytopenia in older adults is rare and can pose significant diagnostic and management challenges. This case adds to the limited literature, illustrating the need for high clinical suspicion, supportive care, and careful monitoring to achieve favorable outcomes.

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2026 Research Recognition Day