Small Cell Lung Cancer With Rapidly Progressive Paraneoplastic Neuropathy

What happened, in summary

A 55-year-old man with a long smoking history developed fever, cough, shortness of breath, and worsening respiratory distress. Imaging showed a right hilar mass with mediastinal involvement, and bronchoscopy confirmed small cell lung cancer. Staging found adrenal metastases, establishing Stage IV disease. His condition was severe enough to require intensive care and mechanical ventilation.

Because small cell lung cancer can respond quickly to treatment, carboplatin and etoposide were started while he was intubated. The cancer responded well: after the first cycle, imaging showed a clear partial response and he was able to come off the ventilator.

During the second cycle, however, he developed back pain and rapidly worsening weakness in both legs. Within days the weakness progressed to all four limbs. Brain and spine imaging did not show cancer spread causing the symptoms, and cerebrospinal-fluid testing did not find malignant cells. Nerve studies showed a severe motor-predominant polyneuropathy with mixed axonal and demyelinating features. Steroids and intravenous immunoglobulin did not reverse the neurologic decline.

Although the lung cancer itself was shrinking, the neurologic syndrome progressed to respiratory compromise. After discussions with his family and care team, he chose supportive rather than further invasive ventilatory care. He died 3 weeks after the neurologic symptoms began.