Objective:

To explore the clinical and genetic aspects of a patient with thymoma-related stiff person syndrome (SPS) and myasthenia gravis (MG), emphasizing the significance of these findings in the context of existing literature.

Key Findings:

• The patient exhibited symptoms including gait instability, rigidity, dysarthria, and dysphagia.
• Serological tests showed elevated anti-GAD65 and AChR antibodies.
• CT scans indicated an anterior mediastinal mass consistent with thymoma.
• Management included immunotherapy and thymectomy, resulting in significant clinical improvement.
• Literature review identified seven additional cases with similar findings and positive outcomes following treatment.
• WES revealed a somatic CACNA1A mutation and variants in immune-signaling genes.

Interpretation:

Thymoma-related SPS and MG represent a rare overlap syndrome, suggesting a unifying mechanism involving thymic neoplasia, disrupted neurotransmission, and autoimmunity, with potential implications for treatment strategies.

Limitations:

• The study is based on a single case and limited literature review, which may not capture the full spectrum of the syndrome.
• Genetic findings may not be generalizable to all cases of thymoma-related SPS and MG due to variability in genetic backgrounds.

Conclusion:

The findings support the notion that thymoma can lead to multiple autoimmune conditions, highlighting the need for comprehensive evaluation and management strategies.