Hello and welcome to HCM, Swelling under the chin can be due to lymph node enlargement. Sub-mental lymph node is present under the chin and it can get enlarged in cases of infection and inflammation. Soft tissue swelling can also cause swelling at this site. An aspiration cytology of the swelling is required to know the nature of the swelling. In aspiration cytology,a needle is inserted into the swelling, cells are aspirated and spread on a glass slide. The cells are stained with appropriate stains and examined microscopically to know the nature of the lesion. Consult your primary healthcare provider for clinical assessment, investigations and thus management. Thanks and take care Dr Shailja Puri