Acute exacerbation of paraneoplastic neurological syndrome after massive tumor lysis of neuroendocrine carcinoma by chemoradiotherapy

We present the case of a 68-year-old woman who presented with a swelling on the left side of her lower jaw. Biopsy revealed neuroendocrine carcinoma of the mandible. Chemoradiotherapy with carboplatin and etoposide with local irradiation induced very rapid remission of the tumor. The massive tumor remission caused severe exacerbation of symptoms, including fatigue and muscle weakness. Her condition was diagnosed as paraneoplastic neurological syndrome with generalized peripheral nerve paralysis and respiratory failure. The syndrome was thought to be triggered by an accelerated immune reaction against the tumor, which attacked neurons with similar antigens to the tumor. The immune attack resulted in overt neurological disturbance that was not well recognized at the time of tumor diagnosis.