Background: Co-occurrence of multiple autoimmune diseases is common, but developing a second autoimmune condition during treatment for an existing one, particularly under immunosuppressive therapy, is rare. This case highlights the development of Muscle Specific Kinase (MuSK) positive Myasthenia Gravis (MG) in a patient with biopsy-proven non-systemic vasculitic neuropathy (NSVN) treated with rituximab. Case Report: A 74-year-old male initially presented with right foot drop, diagnosed as sensorimotor axonal neuropathy. He was treated with methylprednisolone and later rituximab for non-systemic vasculitic neuropathy. Despite some improvement, he developed progressive muscle weakness, bulbar symptoms, and respiratory failure. Anti-MuSK antibodies were positive, confirming MuSK-positive MG. A myositis panel showed borderline anti-Ro52 positivity, and systemic malignancy was excluded. Treatment with pyridostigmine and steroids led to significant recovery, including weaning off mechanical ventilation. Conclusion: The development of MuSK-positive MG during rituximab treatment for NSVN is a novel and paradoxical finding. This case highlights the complexity of diagnosing and managing co-existing autoimmune diseases, suggesting that genetic factors and immune dysregulation may contribute to such occurrences. The patient's response to pyridostigmine and steroids supports an immune-mediated origin for the MG.