Neck Swellings & Differential Diagnosis
ENT · Head & Neck · lean revision notes
Neck Swellings & Differential Diagnosis
A neck swelling is one of the commonest surgical presentations and a perennial NEET PG favourite because the differential turns almost entirely on anatomical location (midline vs lateral), age of the patient, and mobility relationships (tongue, deglutition, mass relations). Master a systematic triangulation approach and most single-best-answer questions answer themselves.
A systematic approach to any neck lump
The clinical "flow" for a neck swelling:
History (age, duration, growth, pain, fever) → Site (midline vs lateral, which triangle) → Movement on swallowing? Movement on tongue protrusion? → Consistency / transillumination / pulsatility / compressibility → FNAC / USG → Definitive imaging (CECT/MRI) or surgery
High-yield: The single most useful first question is where the lump is. Midline swellings have a short, classic list; lateral swellings are dominated by lymph nodes in adults and congenital cysts in children.
Anatomical triangles of the neck (quick recall)
The sternocleidomastoid (SCM) divides the neck into anterior and posterior triangles.
| Triangle | Boundaries | Common swellings |
|---|---|---|
| Anterior triangle | Midline, lower border of mandible, anterior SCM | Thyroid, thyroglossal cyst, submandibular gland, branchial cyst, lymph nodes, carotid body tumour |
| Posterior triangle | Posterior SCM, trapezius, middle 1/3 of clavicle | Cystic hygroma, cervical rib, lymph nodes (including TB, lymphoma, Virchow's node on left), subclavian aneurysm |
High-yield: Posterior triangle lymphadenopathy (especially jugulodigastric/upper deep cervical) in adults should always prompt a search for a head & neck primary (nasopharynx, tonsil) before labelling it benign.
Classification of neck swellings
A reproducible classification used in vivas and MCQs:
- Midline swellings — thyroglossal cyst, dermoid cyst, sublingual dermoid, subhyoid bursitis, Ludwig's angina, isthmus of thyroid, plunging ranula, enlarged pre-/para-tracheal node.
- Lateral swellings — branchial cyst/sinus/fistula, cystic hygroma, carotid body tumour (chemodectoma), cervical lymphadenopathy, cold abscess, salivary gland (submandibular/parotid tail), laryngocele, pharyngeal pouch, sternomastoid tumour.
High-yield: Movement classifiers — moves with deglutition = attached to larynx/trachea/pretracheal fascia (thyroid swellings, thyroglossal cyst). Moves with tongue protrusion = thyroglossal cyst (and thyroid-tissue lesions tethered via the tract). Both are positive for thyroglossal cyst, which is the exam's favourite differentiator.
Midline neck swellings
Thyroglossal cyst
The commonest congenital midline neck swelling and the highest-yield single topic here.
- Embryology: The thyroid develops at the foramen caecum (junction of anterior 2/3 and posterior 1/3 of tongue) and descends along the thyroglossal duct, passing in front of, through, or behind the hyoid bone to reach its pretracheal position. The duct normally obliterates by week 6. Persistent remnants form a thyroglossal cyst.
- Site: Anywhere from foramen caecum to thyroid isthmus; most are subhyoid in the midline (next commonest is at the level of the thyroid cartilage). Cysts may sit slightly off-midline (usually to the left).
- Age: Classically presents in the first/second decade, but can present at any age.
- Signs: Smooth, cystic, fluctuant, transilluminant (if thin-walled), painless midline swelling. Moves up with deglutition AND with tongue protrusion — the latter because the tract is tethered to the hyoid/base of tongue.
High-yield: Movement upwards on protrusion of the tongue is the classic sign of a thyroglossal cyst (tract attached to the hyoid bone and tongue base).
- Investigation of choice: USG neck — confirms cystic nature AND, crucially, confirms presence of a normal orthotopic thyroid gland before any excision (the cyst may contain the only functioning thyroid tissue = "lingual/median ectopic thyroid"). A thyroid scan can be added if ectopic thyroid is suspected.
- Management — drug/procedure of choice: Sistrunk operation = excision of the cyst + the central portion of the body of the hyoid bone + a core of tongue-base tissue up to the foramen caecum. This dramatically lowers recurrence.
High-yield: Sistrunk's operation is the surgery of choice; removing the central hyoid is essential because the tract passes intimately with the hyoid. Simple cyst excision → high recurrence.
- Complications: Recurrent infection, thyroglossal fistula (usually after infection or incomplete excision — an acquired fistula, never truly congenital), and rarely papillary carcinoma arising in the cyst.
Lingual thyroid & ectopic thyroid
Failure of descent leaves thyroid tissue at the tongue base (lingual thyroid) — a smooth midline mass at the foramen caecum; may be the only thyroid tissue, so do imaging before excision.
Dermoid cyst (midline)
- Arises from inclusion of ectoderm along lines of embryonic fusion; submental/sublingual dermoid is the classic midline variant.
- Soft, putty-like, does NOT move with tongue protrusion (key differentiator from thyroglossal cyst), not transilluminant typically, may be doughy.
Ludwig's angina
- A rapidly spreading bilateral cellulitis of the submandibular and sublingual spaces, usually from a mandibular molar (2nd/3rd) dental infection; mixed oral flora.
- Brawny, board-like induration of the floor of mouth, tongue pushed up and back, drooling, trismus, risk of airway obstruction (the lethal complication).
- Management: Secure airway (low threshold for fibreoptic intubation/tracheostomy), IV broad-spectrum antibiotics, surgical decompression of involved spaces, remove the offending tooth.
High-yield: Ludwig's angina is an airway emergency — death is from asphyxia/oedema, not sepsis per se. Definitive airway control is priority one.
Subhyoid bursitis & plunging ranula
- Subhyoid bursitis: cystic midline swelling that moves with swallowing.
- Plunging ranula: a mucous extravasation cyst of the sublingual gland that herniates through mylohyoid into the submental/submandibular region.
Lateral neck swellings
Branchial cyst
- Origin: The vast majority arise from remnants of the second branchial cleft/pouch apparatus.
- Site: At the junction of upper 1/3 and lower 2/3 of the anterior border of SCM, deep to it — i.e., upper anterior triangle.
- Age: Presents typically in young adults (3rd decade), often after an upper respiratory infection that makes it suddenly enlarge.
- Contents: Fluctuant, contains turbid fluid rich in cholesterol crystals (a classic FNAC/aspirate finding).
- Tract relations of a 2nd cleft branchial fistula: opens externally at lower 1/3 anterior SCM, ascends, passes between the internal and external carotid arteries, deep to the posterior belly of digastric, and opens internally at the anterior aspect of the tonsillar fossa.
High-yield: A branchial cyst aspirate showing cholesterol crystals + location at the upper anterior SCM border = classic. In patients >40 years, a "branchial cyst" must be assumed to be a cystic metastasis (e.g., from HPV-related oropharyngeal/tonsillar or papillary thyroid carcinoma) until proven otherwise — do not simply excise; image and seek a primary.
- Branchial sinus/fistula: A persistent opening in the lower anterior neck, often present from birth, discharging mucus.
- Management: Complete surgical excision of cyst/tract (after excluding malignancy in older patients).
Cystic hygroma (cystic lymphangioma)
- A congenital malformation of lymphatic sacs (jugular lymph sac); most present at birth or by 2 years.
- Site: Classically the posterior triangle of the neck (also axilla, groin).
- Soft, brilliantly transilluminant, partially compressible, increases in size on crying/straining.
- Complication: Sudden enlargement from infection or haemorrhage → respiratory compromise.
- Management: Sclerotherapy (intralesional OK-432/picibanil or bleomycin) is increasingly first-line; surgical excision for macrocystic/localised disease.
High-yield: Cystic hygroma = brilliantly transilluminant posterior-triangle swelling in an infant. Transillumination is the single most discriminating bedside sign.
Carotid body tumour (chemodectoma / paraganglioma)
- Tumour of the chemoreceptor cells of the carotid body at the carotid bifurcation.
- Painless, slow-growing mass at the level of the hyoid; pulsatile/transmits pulsation; classically mobile side-to-side but NOT up-and-down (movable horizontally only because it is tethered to the carotid) — the Fontaine sign.
- May be associated with SDH gene mutations, can be familial/bilateral, and a minority secrete catecholamines.
- Investigation of choice: Contrast imaging — CT/MR angiography or digital subtraction angiography shows the pathognomonic splaying of the internal and external carotid arteries = "lyre sign." USG with Doppler shows a vascular mass at the bifurcation.
High-yield: Lyre sign (splaying of ICA & ECA at the bifurcation on angiography) = carotid body tumour. Never do an open/incisional biopsy or FNAC blindly — risk of torrential haemorrhage. Management is surgical excision (after embolisation for large tumours).
- Shamblin classification grades surgical difficulty by how much the tumour encases the carotid vessels (I → III).
Cervical lymphadenopathy
The commonest lateral neck swelling overall, especially in adults.
- Causes: Reactive (infective), tuberculous (cold abscess), metastatic carcinoma, lymphoma.
- Tuberculous lymphadenitis: Matted nodes, classically upper deep cervical; may caseate into a "collar-stud" cold abscess (a soft fluctuant swelling without the signs of acute inflammation — no warmth/redness). Aspirate, do not incise (incision → non-healing sinus). Treat with ATT (anti-tubercular therapy).
- Metastatic node: Hard, fixed; left supraclavicular node = Virchow's node (Troisier's sign) points to a GI/abdominal (gastric) or thoracic primary.
| Lymphadenopathy type | Typical feel | Pointer |
|---|---|---|
| Reactive/infective | Tender, mobile, soft | Resolves with treatment of source |
| Tuberculous | Matted, may caseate (cold abscess) | Evening rise of temperature; ATT |
| Metastatic | Hard, fixed, non-tender | Search head & neck / Virchow's node → abdomen |
| Lymphoma | Rubbery, multiple, mobile | B-symptoms; excision biopsy diagnostic |
High-yield: For a suspected lymphoma node, do an EXCISION biopsy (architecture needed), whereas for a suspected metastatic node, FNAC is the first-line investigation. For tuberculous nodes/cold abscess, aspirate (never incise).
Investigation of choice — the FNAC rule
FNAC (fine-needle aspiration cytology) is the investigation of choice for most solid neck masses and metastatic/tubercular nodes — quick, safe, no track seeding for most lesions, and highly accurate for thyroid and metastatic nodes.
| Lesion | First investigation of choice | Note |
|---|---|---|
| Thyroglossal cyst | USG neck | Confirm normal orthotopic thyroid before surgery |
| Cystic hygroma | Transillumination + USG/MRI | MRI defines extent for surgery |
| Carotid body tumour | CT/MR angiography (lyre sign) | NO biopsy/FNAC — bleeding risk |
| Cervical lymph node (metastatic/TB) | FNAC | Excision biopsy if lymphoma suspected |
| Branchial cyst | USG ± FNAC | In >40 yr, treat as metastasis; image for primary |
| Thyroid nodule | USG + FNAC (Bethesda) | Risk stratification |
High-yield: Memorise the exceptions to "FNAC first": carotid body tumour (angiography, no FNA), suspected lymphoma (excision biopsy), thyroglossal/branchial (image first; FNA limited).
Key differentials side-by-side
| Feature | Thyroglossal cyst | Branchial cyst | Cystic hygroma | Carotid body tumour |
|---|---|---|---|---|
| Typical age | Children/young adults | 3rd decade | Infancy (<2 yr) | 4th–5th decade |
| Site | Midline (subhyoid) | Upper anterior SCM | Posterior triangle | Carotid bifurcation |
| Origin | Thyroglossal duct | 2nd branchial cleft | Jugular lymph sac | Carotid body chemoreceptors |
| Moves with tongue | Yes | No | No | No |
| Transillumination | ± | No | Brilliant | No |
| Pulsatility | No | No | No | Transmitted/pulsatile, Fontaine sign |
| Surgery | Sistrunk | Excision of cyst/tract | Excision/sclerotherapy | Excision ± embolisation |
Mnemonics
- Midline cystic swelling, moves with tongue = Thyroglossal ("Tongue → Thyroglossal").
- Branchial cyst location: "2nd branchial, between 2 carotids (int & ext), opens at the 2nd-arch derivative tonsillar fossa." (Lots of 2s — it's the 2nd cleft.)
- Cold abscess = "collar-stud" with TB; "don't incise, aspirate."
- Lyre sign = carotid body tumour (lyre = a stringed instrument splayed like the splayed carotids).
Recently asked / exam angle
- Thyroglossal cyst moves with tongue protrusion — repeatedly asked single-best-answer differentiator; pair with "tract attached to hyoid bone."
- Sistrunk operation and why the central hyoid must be removed (intimate relation of tract to hyoid) — recurrence question.
- Second branchial cleft as the origin of the typical branchial cyst/fistula; the fistula passes between internal and external carotid arteries — anatomy MCQ.
- Cholesterol crystals on branchial cyst aspirate.
- Branchial cyst in a patient over 40 = cystic metastasis (HPV-related oropharyngeal/papillary thyroid carcinoma) — a modern high-yield twist.
- Cystic hygroma = brilliantly transilluminant posterior-triangle swelling in an infant; OK-432 sclerotherapy.
- Lyre sign / splaying of carotids = carotid body tumour, and the rule "no FNAC/biopsy."
- Virchow's node (Troisier's sign) on the left supraclavicular fossa → gastric/abdominal primary.
- Cold abscess in neck — aspirate, don't incise; Ludwig's angina is an airway emergency.
- FNAC is investigation of choice for cervical lymphadenopathy; excision biopsy when lymphoma is suspected.
Rapid revision
- Decide midline vs lateral first — it narrows the differential more than anything else.
- Moves with deglutition = laryngotracheal attachment (thyroid, thyroglossal cyst); moves with tongue protrusion = thyroglossal cyst.
- Thyroglossal cyst is usually subhyoid; do USG first to confirm a normal orthotopic thyroid; treat by Sistrunk operation (excise central hyoid).
- Thyroglossal fistula is acquired (post-infection/incomplete surgery), never truly congenital.
- Dermoid cyst does NOT move with tongue protrusion — key separator from thyroglossal cyst.
- Branchial cyst = upper anterior SCM, 2nd branchial cleft, aspirate has cholesterol crystals; in >40 yr think cystic metastasis.
- 2nd branchial fistula runs between internal & external carotids to the tonsillar fossa.
- Cystic hygroma = infant, posterior triangle, brilliantly transilluminant, treat with OK-432 sclerotherapy or excision.
- Carotid body tumour = pulsatile mass at bifurcation, Fontaine sign (mobile side-to-side only), lyre sign on angiography, never biopsy.
- Cold (tuberculous) abscess = "collar-stud," aspirate not incise, treat with ATT.
- Virchow's node (left supraclavicular) = Troisier's sign → gastric/abdominal primary.
- FNAC is the go-to for most neck nodes; excision biopsy for suspected lymphoma; Ludwig's angina is an airway emergency.