Complete atrioventricular block because of cardiac metastases from buccal mucosa squamous cell carcinoma: a case report and literature review

Cardiac metastases are an uncommon clinical entity and are rarely associated with head and neck squamous cell carcinomas, particularly those originating in the buccal mucosa. We report a rare case of a 28-year-old male with previously treated buccal mucosa squamous cell carcinoma who presented with fatigue, dizziness and dyspnoea and was found to have complete atrioventricular block on electrocardiography, prompting further cardiac evaluation. Transthoracic echocardiography demonstrated multiple intracardiac masses with septal involvement, which were further characterised by computed tomography pulmonary angiography and high-resolution computed tomography of the chest, confirming extensive cardiac infiltration. Histopathological examination of metastatic cervical lymph nodes confirmed squamous cell carcinoma. Owing to persistent symptomatic complete atrioventricular block, the patient underwent single-chamber permanent pacemaker implantation following multidisciplinary discussion. This case highlights the importance of considering cardiac metastases in patients with advanced head and neck malignancies presenting with new-onset conduction abnormalities. A focussed review of the literature is also presented.