2025 Volume 65 Issue 2 Pages 91-95
Background. Paraneoplastic neurological syndromes (PNS) are a group of neurological disorders potentially caused by immunological mechanisms, triggered by an underlying tumor, and are rarely associated with thymic carcinoma. Case. The patient was a 73-year-old man who had experienced plantar numbness and reduced vibration perception for the past 5 years. Additionally, he had difficulty going up and down stairs due to leg weakness. A nerve conduction study revealed a wide range of neurodegenerative alterations. Additionally, chest computed tomography revealed a 24-mm solid tumor in the anterior mediastinal region. Although the only positive paraneoplastic neurological antibody was anti-titin, we suspected PNS due to the presence of a thymoma and thus performed an extended thymo-thymectomy. The tumor was located in the right upper pole of the thymus and was macroscopically encapsulated, with no obvious invasion. The tumor cells exhibited atypical nuclei and tested positive for CD5 and c-kit. The tumor demonstrated microscopic transcapsular invasion into the surrounding fatty tissue and was diagnosed as a thymic squamous cell carcinoma (pT1aN0M0; Masaoka-Koga classification stage IIa). The right lower leg numbness and muscle weakness were significantly enhanced after surgery, and fasciculation disappeared on electromyography. Conclusion. When encountering unexplained neurological symptoms, thymic carcinoma should therefore be considered in the differential diagnosis. Active early treatment of the tumor is crucial to prevent the worsening of neurological symptoms.
