Rare oral metastasis from a probable large-cell neuroendocrine carcinoma of the lung

Abstract

Introduction: The prevalence of neuroendocrine tumors is 1/100 000 worldwide. Lung locations account for 25% and the oral cavity is very rarely involved. Observation: We reported the case of gingival hyperplasia around an upper molar in a patient with a medical history of lung adenocarcinoma treated by targeted chemotherapy. Incisional biopsy of the intraoral lesion revealed a large-cell neuroendocrine carcinoma (LCNEC). New imaging assessment revealed multiple metastasis locations of the lung disease. This case made us question the link between gingival LCNEC and the lung adenocarcinoma diagnosed through pleural cytology. Review of cytology findings did not make it possible to identify a neuroendocrine component among adenocarcinoma cells. Immunohistochemical tools sometimes help to differentiate primary from secondary lesions, but this was inconclusive here. Discussion: The literature shows that in cases of lung composite carcinoma, one component may be absent on small histology samples, and therefore on cytology. It was not possible either to rule out neuroendocrine carcinoma development under the effect of targeted chemotherapy. We considered the diagnosis of intraoral metastasis of a composite lung carcinoma which metastasized to its neuroendocrine component in the oral cavity. Conclusion: To our knowledge, this is the first case of LCNEC gingival hyperplasia revealing metastatic progression of lung adenocarcinoma.