What are the differential diagnoses for a 12-year-old boy with right-sided neck swelling and pain, and a history of similar complaints?

Differential Diagnoses for Right-Sided Neck Swelling with Pain in a 12-Year-Old Boy

In a 12-year-old boy with recurrent right-sided neck swelling and pain, the most likely diagnoses are reactive lymphadenopathy from infectious causes (viral or bacterial), followed by congenital lesions (branchial cleft cyst, thyroglossal duct cyst), and less commonly, inflammatory or neoplastic processes.

Primary Differential Diagnoses by Category

Infectious/Inflammatory Causes (Most Common in This Age Group)

• Reactive lymphadenopathy from viral upper respiratory infections, Epstein-Barr virus, or bacterial infections represents the most frequent etiology in pediatric patients, particularly with a history of recurrent episodes 1
• Bacterial lymphadenitis from Staphylococcus aureus or Streptococcus species should be considered, especially if the mass is tender, warm, and associated with systemic symptoms 2
• Retropharyngeal or deep neck space abscess can present with neck pain and swelling, though typically accompanied by dysphagia, fever, and limited neck range of motion 3
• Cat-scratch disease (Bartonella henselae) causes persistent lymphadenopathy in children with feline exposure 1

Congenital Lesions (Important in Recurrent Cases)

• Branchial cleft cyst (second branchial cleft most common) presents as a lateral neck mass that may become inflamed and painful during upper respiratory infections, explaining the recurrent nature 1, 2
• Thyroglossal duct cyst typically presents in the midline but can be paramedian, and may become infected causing pain and swelling 2
• Lymphatic malformations (cystic hygromas) can present with intermittent swelling, particularly after infection or hemorrhage into the lesion 1

Less Common but Important Considerations

• Mycobacterial infection (tuberculous or atypical mycobacteria) causes chronic, painless lymphadenopathy that may become painful with secondary infection 1, 2
• Neoplastic processes are less common in children than adults but include lymphoma (Hodgkin's and non-Hodgkin's) and rarely rhabdomyosarcoma 4, 1

Red Flags Requiring Urgent Evaluation

The American College of Radiology identifies specific red flags that mandate further investigation beyond simple observation 5, 6:

• Constitutional symptoms: Fever, unexplained weight loss, night sweats 5, 6
• Mass characteristics: Size >1.5 cm, firm consistency, fixed to adjacent tissues, duration ≥2 weeks without improvement 4
• Elevated inflammatory markers: Elevated white blood cell count, ESR, or CRP 5, 6
• Associated symptoms: Dysphagia, voice changes, or respiratory symptoms suggesting deep space involvement 6, 3
• Immunocompromised status or history of IV drug use increases infection risk 5

Diagnostic Approach Algorithm

Initial Clinical Assessment

• Location specificity: Right-sided location suggests lateral neck pathology—lymph nodes, branchial cleft cyst, or salivary gland involvement 2
• Recurrence pattern: History of similar complaints suggests either recurrent infection of lymph nodes, intermittent inflammation of a congenital cyst, or chronic infectious process 1, 7
• Pain characteristics: Acute onset pain with swelling favors infectious etiology; chronic painless mass that becomes painful suggests infected congenital lesion 1, 2

Imaging Recommendations

• Ultrasound with Doppler is the first-line imaging modality for pediatric neck masses, providing excellent soft tissue characterization, distinguishing solid from cystic lesions, and assessing vascularity without radiation exposure 2
• Contrast-enhanced CT of the neck is indicated if red flags are present, deep space infection is suspected, or ultrasound findings are inconclusive 8, 4
• MRI without contrast should be reserved for cases with suspected vascular malformations, neurological symptoms, or when malignancy cannot be excluded 6, 8

Laboratory Evaluation

• Complete blood count with differential to assess for leukocytosis or atypical lymphocytosis 5
• Inflammatory markers (ESR, CRP) if systemic inflammatory process or chronic infection suspected 5, 6
• Monospot or EBV serology if infectious mononucleosis suspected 1
• Purified protein derivative (PPD) or interferon-gamma release assay if mycobacterial infection considered 1

Tissue Diagnosis

• Fine needle aspiration (FNA) is indicated for persistent masses (>4-6 weeks), masses with concerning features, or when malignancy cannot be excluded clinically 4, 2
• Excisional biopsy may be required for definitive diagnosis of congenital lesions or if FNA is non-diagnostic 1, 2

Management Based on Most Likely Diagnosis

If Infectious Lymphadenopathy Suspected (No Red Flags)

• Trial of observation for 2-4 weeks if viral etiology suspected, as most reactive lymphadenopathy resolves spontaneously 1
• Single course of broad-spectrum antibiotics (covering Staphylococcus and Streptococcus) if bacterial lymphadenitis suspected, with mandatory reassessment within 2 weeks 4
• Critical pitfall: Multiple courses of antibiotics without definitive diagnosis delays recognition of other pathology 4

If Congenital Lesion Suspected

• Ultrasound imaging to characterize the lesion (cystic vs. solid, relationship to surrounding structures) 2
• Referral to pediatric otolaryngology for surgical planning if branchial cleft cyst or thyroglossal duct cyst confirmed 1
• Infected congenital cysts require antibiotics first, followed by delayed surgical excision after inflammation resolves 1

If Red Flags Present

• Immediate imaging with contrast-enhanced CT or ultrasound depending on suspected pathology 6, 8, 4
• Urgent referral to pediatric otolaryngology for evaluation and consideration of FNA or biopsy 4
• Laboratory evaluation including inflammatory markers and complete blood count 5, 6

Important Clinical Pitfalls

• Assuming all pediatric neck masses are infectious without considering congenital lesions, particularly with recurrent presentation 1
• Prescribing multiple antibiotic courses without tissue diagnosis or imaging delays recognition of congenital or neoplastic pathology 4
• Failure to reassess within 2 weeks after initial antibiotic trial allows progression of unrecognized serious pathology 4
• Overlooking deep space infections that can present with neck swelling but require urgent surgical drainage 3