Differentiating Parotitis from Lymphadenitis

Clinical Features

The American Academy of Otolaryngology-Head and Neck Surgery notes that parotitis involves swelling within the parotid gland itself, while lymphadenitis presents as discrete, mobile nodules that are separate from the parotid gland and typically located along the anterior or posterior cervical chain 1
Systemic viral symptoms, such as mumps, EBV, or CMV, may be present in acute viral parotitis, as reported by the Infectious Diseases Society of America 2
Recent upper respiratory infection is reported in 22-53% of lymphadenitis cases, according to the American Thoracic Society 3
Unilateral presentation occurs in 95% of lymphadenitis cases, as stated by the American Journal of Respiratory and Critical Care Medicine 4
Age is a factor in lymphadenitis, with nontuberculous mycobacteria (NTM) being most common in children aged 1-5 years, and tuberculous lymphadenitis being more common in adults, as reported by the American Journal of Respiratory and Critical Care Medicine 4

The American College of Radiology recommends ultrasound as the first-line imaging modality for suspected parotitis, to differentiate intraparotid vs. extraparotid masses and identify stones or duct dilation 5
The American Thoracic Society suggests a tuberculin skin test (PPD) in all patients with suspected mycobacterial lymphadenitis, as well as a chest X-ray to exclude pulmonary TB 4
Fine-needle aspiration (FNA) is recommended for cytology and culture (mycobacterial, bacterial) in suspected lymphadenitis, as stated by the American Journal of Respiratory and Critical Care Medicine 4

The Infectious Diseases Society of America recommends empiric antibiotics covering Staphylococcus aureus and Group A Streptococcus for bacterial lymphadenitis, such as amoxicillin-clavulanate or cephalexin 2
The American Thoracic Society suggests complete surgical excision without chemotherapy for NTM lymphadenitis in children, with a 95% cure rate 4
Standard 4-drug TB therapy (isoniazid, rifampin, pyrazinamide, ethambutol) is recommended for 6-9 months for tuberculous lymphadenitis, as stated by the American Journal of Respiratory and Critical Care Medicine 4

The European Respiratory Journal recommends considering loss of normal hilar architecture as a key sonographic feature for TB lymphadenitis diagnosis 6
The Journal of the American College of Radiology suggests that peripheral vascularity on Doppler imaging is a valuable feature for diagnosing TB lymphadenitis 7
The American Journal of Respiratory and Critical Care Medicine notes that unilateral involvement is present in 95% of NTM lymphadenitis cases, which can help distinguish it from TB lymphadenitis 8

The Journal of the American College of Radiology recommends using CT as a complementary modality in complicated cases, particularly in immunocompromised patients, to reveal subtle mediastinal lymphadenopathy 7
The Journal of the American College of Radiology also suggests that CT provides better anatomical localization of deep lymph nodes not accessible to ultrasound, and can be used in conjunction with ultrasound to optimize management 9