Oral medicine: 10. lumps and swellings: neck

Neck lumps

The lymphoid system is the essential basis of immune defences and comprises predominantly bone marrow, spleen, thymus and lymph nodes. Tissue fluid drains into lymph nodes which act as ‘filters’ of antigens and, after processing in the nodes, lymph containing various immunocytes drains from the nodes to lymph ducts and then to the circulation. A lymph node consists of a cortex, paracortex and medulla and is enclosed by a capsule. Lymphocytes and antigens (if present) pass into the node through the afferent lymphatics, are ‘filtered’, and pass out from the medulla through the efferent lymphatics. The cortex contains B cells aggregated into primary follicles; following stimulation by antigen these develop a focus of active proliferation (germinal centre) and are termed secondary follicles. These follicles are in intimate contact with antigen-presenting dendritic cells. The paracortex contains T cells, and the medulla contains T and B cells.

Causes of lymph node enlargement

Many diseases can present with lesions in the neck but the most common are lesions involving the lymph nodes (Table 1).

Lymph nodes enlarge in oral infections or local infections in the drainage area (virtually anywhere in the head and neck). Most common is an enlarged jugulo-digastric (tonsillar) lymph node, inflamed secondary to a viral upper respiratory tract infection. Children and young adults are predominantly affected (Table 2). Enlarged cervical lymph nodes may also be related to malignant disease in the drainage area (eg carcinoma) or may be a manifestation of systemic disease (eg HIV/AIDS). Adults are predominantly affected.

Examination of cervical lymph nodes

The examination of lymph nodes in the neck is an important part of every orofacial examination. About one-third of all the lymph nodes in the body are in the neck and dental surgeons can often detect serious disease through their examination of the neck.

Inspection of the neck, looking particularly for swellings or sinuses, should be followed by careful palpation of the thyroid gland and all the lymph nodes, searching for swelling or tenderness.

It is prudent to adopt a systematic and methodical approach examining different lymph node groups in turn:

Both anterior and posterior cervical nodes should be examined as well as other nodes, liver and spleen if systemic disease is a possibility. Most disease in lymph nodes is detected in the anterior triangle of neck, which is bounded superiorly by the mandibular lower border, posteriorly and inferiorly by the sternomastoid muscle, and anteriorly by the midline of the neck. Nodes in this site drain most of the head and neck, except the occiput and back of neck. Lymphadenopathy in the anterior triangle of the neck alone is often due to local disease, especially if the nodes are enlarged on only one side.

A limited number of lymph nodes swell usually because they are involved in an immune response to an infectious agent in the area of drainage and nodes are then often firm, discrete and tender, but are mobile (lymphadenitis). The focus of inflammation can usually be found in the drainage area, which is anywhere on the face, scalp and nasal cavity, sinuses, ears, pharynx and oral cavity. Lymph nodes that are tender may be inflammatory, leukaemia or lymphoma; those that are increasing in size and are hard may be malignant.

Lymph nodes may show reactive hyperplasia to a malignant tumour in the drainage area, or swelling because of metastatic infiltration. The latter may cause the node to feel distinctly hard, and it may become bound down to adjacent tissues (‘fixed’), may not be discrete, and may even, in advanced cases, ulcerate through the skin. The neoplasms that frequently metastasize to cervical lymph nodes are oral squamous carcinoma (Article 3), nasopharyngeal carcinoma, tonsillar cancer and thyroid tumours.

Usually one or more anterior cervical nodes are involved, often unilaterally in oral neoplasms anteriorly in the mouth, but otherwise not infrequently bilaterally.

Generalized lymphadenopathy with or without enlargement of other lymphoid tissue, such as liver and spleen (hepatosplenomegaly), suggests a systemic cause.

The local cause may not always be found despite a careful search. For example, children occasionally develop a Staphylococcus aureus lymphadenitis (usually in a submandibular node) in the absence of any obvious portal of infection.

More serious is the finding of an enlarged node suspected to be malignant but where the primary neoplasm cannot be found. Nasopharyngeal or tonsillar carcinomas are classic causes of this and an ENT opinion should therefore be sought. Clinically unsuspected tonsillar cancer is a common cause of metastasis in a cervical node. Biopsy of the tonsil may reveal a hitherto unsuspected malignancy.

Rare causes of cervical metastases include metastases from stomach or even testicular tumours to lower cervical nodes. However, in some patients with a malignant cervical lymph node, the primary tumour is never located.

Lymph nodes may also swell when there are disorders involving the immune system more generally, such as the glandular fever syndromes, HIV/AIDS and related syndromes, various other viral infections; bacterial infections such as syphilis and tuberculosis; and parasites such as toxoplasmosis. In the systemic infective disorders the nodes are usually firm, discrete, tender and mobile. Lymph nodes may also swell in non-infective lesions such as sarcoidosis, mucocutaneous lymph node syndrome, and neoplasms such as lymphomas and leukaemias (Table 1). In the latter instances, and in the glandular fever syndromes (where there is lymphadenopathy often together with sore throat and fever; Table 3), there is usually enlargement of many or all cervical lymph nodes and in some there is involvement of the whole reticulendothelial system, with generalized lymph node enlargement (detectable clinically in neck, groin and axilla) and enlargement of the liver and spleen (hepatosplenomegaly). In the lymphomas particularly, the nodes may be rubbery, matted together and fixed to deeper structures.