The "numb chin syndrome": A case report.

Introduction: Neuroendocrine tumours comprise 0.5-2% of all malignancies in adulthood, and very rarely metastasize to the oral cavity. When they do metastasize to the oral cavity, the mandible is the most common site. This can lead to symptoms such as a numb chin and lip, which in the absence of any odontogenic cause may be an important sign indicating malignant disease. We present a rare case of metastatic neuroendocrine carcinoma to the mandible, resulting in the so-called "numb chin syndrome".

Presentation Of Case: An elderly lady presented with numbness to the right chin and lip, as well as hypoglossal nerve palsy. She had significant back pain and gave a history of repeat chest infections. Intra-oral clinical examination was normal, but upon further special investigations, the right mental region was suspicious of multiple lytic lesion. Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) demonstrated marrow changes in the mandible suspicious of malignant disease. Further findings included multiple pathological fractures of the spine and a mass in the left lung base. A trephine biopsy gave a diagnosis of metastatic neuroendocrine carcinoma, with the left lung mass considered to be the primary site.

Discussion: We discuss the rarity of metastatic disease to the oral cavity, and the importance of "numb chin syndrome" in indicating malignancy.

Conclusions: This case promotes the importance of considering sinister pathology when presented with sudden, altered sensation to the chin and lips. The "numb chin syndrome" should always raise the suspicion of primary or metastatic disease to the mandible.