Neck masses in children — formative SAQs

SAQ 1 (10 marks)

A 3-year-old boy is brought by his parents with a four-week history of a painless lump in the right side of the neck. He is otherwise well, feeding normally, with no fever, weight loss or night sweats. On examination there is a 2.5 cm firm, non-tender mass in the right anterior triangle of the neck, with overlying skin that has a faint violet-grey discolouration. He is afebrile and systemically well. ^{[1] [3]}

1. What is the most likely diagnosis, and which two features of the history and examination support it? (3) ^[3]
2. Outline your investigation and management plan, naming the first-line imaging test and the definitive treatment. (4) ^{[2] [3]}
3. Describe the key pitfall to avoid and how you would distinguish this from tuberculous lymphadenitis. (3) ^[3]

Model answer — SAQ 1

(1) Diagnosis (3). The most likely diagnosis is non-tuberculous mycobacterial (NTM) cervicofacial lymphadenitis. The two supporting features are the classic age and behaviour — an otherwise well child aged one to five years with a chronic (four-week), unilateral, painless, slowly enlarging cervical node and minimal or no systemic upset — and the characteristic violet-grey discolouration of the overlying skin, which is a hallmark of NTM lymphadenitis as the granulomatous process thins and discolours the skin. This is one of the commonest chronic cervical masses in the young-child age band. ^{[3] [1]}

(2) Investigation and management (4). The first-line imaging test is ultrasound, which confirms the nodal mass, defines its architecture and excludes abscess formation or an underlying congenital cyst. The definitive treatment, as set out by the International Pediatric Otolaryngology Group consensus, is complete surgical excision. Medical therapy with a clarithromycin-based multidrug regimen is reserved for the case in which complete excision would endanger the facial nerve or skin, or for residual or recurrent disease. I would refer the child to paediatric otolaryngology for surgical planning rather than aspirate or drain the node. ^{[2] [3]}

(3) Pitfall and distinction from tuberculosis (3). The key pitfall is incision and drainage under the impression that the node is a pyogenic abscess, which in NTM disease creates a chronic discharging sinus and makes subsequent management far harder — the correct treatment is complete surgical excision. To distinguish NTM from tuberculous (TB) lymphadenitis, I would use a tuberculin skin test or interferon-gamma release assay, a chest radiograph, and aspiration or biopsy for acid-fast bacilli, mycobacterial culture and polymerase chain reaction: TB lymphadenitis typically shows a positive IGRA or strongly positive tuberculin test with systemic or contact-history features and is treated with standard antitubercular therapy, whereas NTM disease occurs in an otherwise well child with a normal chest radiograph and is treated surgically. ^[3]