Complete remission of stage IV sinonasal small cell neuroendocrine carcinoma: A case report.

Sinonasal small cell carcinoma (SmCC) is a rare type of neoplasm. The current case report describes the case of a 30-year-old male patient with stage IV SmCC who underwent concurrent radiotherapy (RT) plus etoposide-cisplatin treatment. Positron emission tomography (PET)/computed tomography (CT) and fibroscopy examination showed complete remission at 3 months post-treatment. However, leptomeningeal metastasis (LM) occurred at 9 months. A literature search identified no previous case reports describing LM of SmCC. The patient was treated with concurrent RT plus irinotecan-gemcitabine. During the sixth cycle of irinotecan-gemcitabine, the patient required intensive care admission due to severe acute respiratory syndrome-related coronavirus 2-associated pneumonia. Following clearance of the pneumonia, LM was assessed using PET/CT and MRI at 3 months, which revealed a complete response to irinotecan-gemcitabine. In May 2021, the patient succumbed to LM following disease recurrence. The findings of this case report should encourage other authors to publish their treatment outcomes regarding SmCC. More clinical trials are required to achieve better results in terms of patient outcome.