Stiff-Person Syndrome with Anti-Amphiphysin Antibodies: A Paraneoplastic Phenomenon Revealing Breast Cancer in a 77-Year-Old Male

Abstract – Introduction: Stiff-person syndrome is a neurological disorder characterized by painful muscle cramps and progressive muscle spasticity. In patients with positive anti-amphiphysin antibodies, there is an association with malignancies such as breast carcinomas and small cell lung cancers. Case Presentation: We report the case of a 77-year-old male patient who developed symptoms of anti-amphiphysin positive stiff-person syndrome and was diagnosed with breast cancer. After immunomodulatory and curative-intent oncological treatment, the patient experienced marked improvement in his neurological symptoms. Conclusion: This case is an example of the importance of multidisciplinary care and thorough oncological workup in a case of stiff-person syndrome with positive anti-amphiphysin antibodies.