Unilateral Cervical Lymphadenopathy

Unilateral cervical lymphadenopathy is enlargement of lymph nodes confined to one side of the neck. It is a common clinical finding with a broad differential diagnosis spanning reactive, infective, granulomatous and malignant causes.

The clinical approach is guided heavily by the patient's age, the duration and character of the lymphadenopathy, and associated features. The likelihood of malignancy differs fundamentally between, for example, a young child with a recent upper respiratory infection and an older adult smoker with a persistent, firm node.

Aetiology by broad category

• Reactive lymphadenopathy reflects a normal immune response to a local or regional infective or inflammatory process (upper respiratory tract infection, dental infection, scalp infection). It is by far the commonest cause across all age groups, particularly in children.
• Specific infective causes produce more prominent or persistent unilateral lymphadenopathy. They include bacterial lymphadenitis (typically Staphylococcus aureus or Streptococcus pyogenes, particularly in young children), cat scratch disease, tuberculous or non tuberculous mycobacterial lymphadenitis, and, less commonly, toxoplasmosis.
• Malignant causes are the diagnoses of greatest clinical concern, and the assessment must specifically aim to identify or exclude them. They include lymphoma, which may present with unilateral or bilateral involvement.
• In an older adult, metastatic squamous cell carcinoma from a head and neck primary is of particular importance.

• Node characteristics on examination provide important, though imperfect, diagnostic clues. Soft, mobile, tender nodes generally favour a reactive or infective process. Firm, fixed, non tender, progressively enlarging nodes raise greater concern for malignancy, particularly in an older patient.
• Duration is a key discriminating feature. Lymphadenopathy persisting or progressively enlarging beyond four to six weeks, particularly without an identified or resolving infective trigger, warrants more active investigation rather than continued observation.
• Associated features that should heighten concern for malignancy include unexplained weight loss, night sweats, and persistent fever (B symptoms suggestive of lymphoma).
• Other features raising concern for malignancy are a smoking or significant alcohol history with symptoms of a head and neck primary (hoarseness, dysphagia, otalgia, oral or laryngeal lesion), or a known or suspected primary malignancy elsewhere.
• Features suggesting a specific infective cause include a history of cat exposure or scratch (cat scratch disease), known tuberculosis exposure or relevant epidemiological risk, and dental or oropharyngeal infection with regional nodal drainage.
• Recent upper respiratory tract infection in a child with otherwise typical reactive lymphadenopathy also suggests an infective cause.
• Fluctuance suggests suppuration. Overlying skin changes (erythema, sinus formation, particularly characteristic of non tuberculous mycobacterial lymphadenitis in young children) also inform the assessment.
• So does the anatomical location of the node. Supraclavicular lymphadenopathy carries particular concern for underlying malignancy, given its drainage from thoracic and abdominal structures.

• A thorough head and neck examination is essential where malignancy is a genuine clinical concern based on age, risk factors or node characteristics. It includes inspection of the oral cavity and oropharynx.
• In adults, particularly smokers, add flexible nasoendoscopy to examine the nasopharynx, larynx and hypopharynx for a potential primary malignant lesion.
• Ultrasound is a useful, accessible first line imaging investigation. It characterises node size, shape, internal architecture and vascularity.
• Loss of the normal fatty hilum, rounded rather than oval shape, and abnormal vascular pattern raise concern for malignant or significant pathological involvement.
• Fine needle aspiration cytology, performed under ultrasound guidance, is the key investigation for any persistent, enlarging or otherwise concerning node. It gives rapid cytological assessment.
• Core biopsy or excisional biopsy may be required for definitive diagnosis where cytology is non diagnostic. Excisional biopsy is needed where lymphoma is specifically suspected, as it provides the architectural assessment that fine needle aspiration alone does not.
• Where an infective cause is suspected, direct specific testing accordingly. Use Bartonella henselae serology for suspected cat scratch disease.
• Use tuberculin skin testing or interferon gamma release assay, with node sampling for mycobacterial culture and molecular testing, where tuberculous or non tuberculous mycobacterial lymphadenitis is suspected. Use Epstein Barr virus or toxoplasma serology where clinically relevant.
• In children with typical reactive lymphadenopathy and a clear preceding infective trigger, a period of observation with reassessment after two to four weeks is generally appropriate before more invasive investigation.
• Reserve prompt biopsy for nodes with concerning features: rapid growth, hardness, fixation, systemic symptoms, or persistence beyond the expected resolution period.

• Reactive lymphadenopathy secondary to an identifiable, resolving infective trigger requires no specific treatment beyond management of the underlying cause and reassurance, with the expectation of gradual resolution over several weeks.
• Suppurative bacterial lymphadenitis is treated with an antibiotic course covering Staphylococcus aureus and Streptococcus pyogenes. This is typically flucloxacillin 500 mg to 1 g four times daily (or clindamycin in penicillin allergy) for seven to ten days.
• A fluctuant, frankly suppurative node not responding to antibiotic therapy alone requires incision and drainage.
• Cat scratch disease is generally self limiting and managed supportively in the immunocompetent host. Consider azithromycin for more significant or persistent lymphadenopathy.
• Tuberculous lymphadenitis is treated with standard antituberculous therapy as detailed under tuberculosis.
• Non tuberculous mycobacterial lymphadenitis in children is generally treated with surgical excision. Response to antimicrobial therapy alone is relatively poor, and incomplete excision or drainage alone risks chronic discharging sinus formation.
• Suspected or confirmed malignancy (lymphoma or metastatic squamous cell carcinoma from a head and neck primary) is managed according to the specific diagnosis established on biopsy. Refer promptly to the relevant oncology or head and neck cancer multidisciplinary team.
• A structured, time limited period of clinical observation, with clear safety netting advice on features that should prompt earlier reassessment, is appropriate for lymphadenopathy with a clear benign explanation and reassuring characteristics.
• Any node with concerning features, or persisting beyond the expected resolution timeframe, warrants prompt further investigation rather than prolonged watchful waiting.