Large cell neuroendocrine carcinoma on the floor of the mouth: a rare entity in an unusual location.

Neuroendocrine carcinomas (NEC) are a group of malignant neoplasms usually located in the lungs or gastrointestinal tract. Fewer cases are located in the head and neck, and in these rare presentations, the lingual tonsil, larynx, and major salivary glands are the most frequently affected sites. NECs exhibit similar characteristics regardless of where they arise. However, because these neoplasms are rare, a clear understanding of their aetiopathogenesis has yet to be described, and options for treatment have varied and are not unified. A rare NEC of the floor of the mouth is reported here; it appears that this location has not been reported previously. The diagnosis was established through histopathological analysis, and the patient underwent systemic treatment. He had a partial response to treatment in the first 3 months, but died 6 months after the initial diagnosis. This highly uncommon tumour can pose a significant diagnostic challenge for clinicians and pathologists alike and can result in diagnostic delay.