Describe the clinical approach to a swelling in the neck.

Anatomy and the Triangles

• A neck swelling is a common presentation with a wide differential.
• The approach rests on three questions — the age of the patient, the site of the swelling, and the duration — which together narrow the diagnosis before any investigation.
• The neck is divided by sternocleidomastoid into anterior and posterior triangles

Clinical Approach and Investigation

• The age OF the patient IS the first discriminator, and it is decisive:
• In a child or young adult, a neck swelling is inflammatory or congenital — reactive lymphadenitis, tuberculosis, a branchial or thyroglossal cyst, cystic hygroma
• In an adult over 40, a persistent neck swelling is metastatic squamous carcinoma until proved otherwise, and the primary must be sought in the upper aerodigestive tract
• The classical teaching that "a lump in the neck of an adult over 40 is a secondary until proved otherwise" remains sound, and is the single most important sentence in this answer
• Duration — days suggests infection; weeks to months suggests neoplasia or granulomatous disease; and years, unchanged, suggests a benign or congenital lesion
• Site — midline: thyroglossal cyst (which moves on swallowing and on protruding the tongue), thyroid isthmus, dermoid, submental node; anterior triangle: lymph nodes, branchial cyst, carotid body tumour, salivary gland; posterior triangle: nodes, cystic hygroma, lipoma
• The history must include A systematic enquiry for A primary — hoarseness, dysphagia, odynophagia, referred otalgia, a unilateral middle ear effusion, nasal obstruction or epistaxis, a mouth ulcer, and weight loss
• Ask about smoking, alcohol, tobacco and betel quid chewing; and about fever, night sweats, weight loss, TB contact and travel
• Examination of the swelling — site, size, shape, surface, consistency, mobility, fixity to skin or deep structures, tenderness, pulsatility, transillumination and fluctuation
• A hard, fixed, non-tender node in an adult is malignant until proved otherwise
• A pulsatile swelling or one with a bruit suggests a carotid body tumour (chemodectoma) or an aneurysm — a carotid body tumour is characteristically mobile side to side but not vertically (fontaine sign), and must not be biopsied or aspirated blindly
• Then examine the whole upper aerodigestive tract — the oral cavity with palpation of the tongue base and floor of mouth, the ears, the nose, and flexible nasendoscopy of the nasopharynx, oropharynx, hypopharynx and larynx. Examining the neck without examining the mucosa is incomplete
• Examine the scalp and skin, the thyroid, the axillae, the abdomen for hepatosplenomegaly, and all node groups
• Investigation — the order matters greatly:
• Ultrasound with fine needle aspiration cytology (FNAC) is the first-line investigation; it is safe, cheap, repeatable and does not seed tumour or compromise later surgery
• Ultrasound features suggesting malignancy — a round shape with a short-to-long axis ratio above 0.5, loss of the fatty hilum, irregular margins, necrosis, microcalcification (suggesting papillary thyroid carcinoma), and peripheral vascularity
• CT of the neck and chest, and MRI for extent and for a primary; with pet-CT where FNAC shows carcinoma and no primary is found
• Examination under anaesthesia with panendoscopy and directed biopsies where a primary is suspected but not seen
• Blood tests as indicated — full blood count, ESR, Mantoux or interferon-gamma release assay, HIV serology, EBV serology, thyroid function and, in a young adult, tests for infectious mononucleosis and toxoplasmosis
• The cardinal rule OF management: never perform AN open (excision) biopsy OF A neck node AS A first step
• The reasons must be given — it seeds tumour into the tissue planes and skin, increases local recurrence and the risk of distant metastasis, compromises a subsequent neck dissection and requires the scar to be excised, and the diagnosis could almost always have been made by FNAC
• Open biopsy is justified only where lymphoma is suspected and FNAC has been non-diagnostic.
• A persistent lump in an adult over forty is a secondary until proved otherwise, which remains the soundest teaching in this topic
• Never open-biopsy a neck node first; it seeds tumour, worsens recurrence and compromises the later dissection