Differential Diagnosis for Swollen Lymph Node on Right Side of Neck

Single Most Likely Diagnosis

• Viral Pharyngitis: This is often the most common cause of a swollen lymph node in the neck, especially if the patient has symptoms of a recent upper respiratory infection. The lymph node swelling is usually reactive, meaning it's a response to an infection rather than a disease of the lymph node itself.

Other Likely Diagnoses

• Bacterial Pharyngitis: Similar to viral pharyngitis, bacterial infections like streptococcal pharyngitis can cause lymphadenopathy (swollen lymph nodes) in the neck.
• Dental Infection: Infections of the teeth or gums can drain to the lymph nodes in the neck, causing them to swell.
• Skin Infections: Cellulitis, abscesses, or other skin infections on the face or neck can cause lymphadenopathy.

Do Not Miss Diagnoses

• Lymphoma: Although less common, lymphoma (both Hodgkin and non-Hodgkin types) can present with lymphadenopathy. It's crucial to consider this diagnosis, especially in patients with persistent, painless lymph node enlargement.
• Metastatic Cancer: Cancers of the head and neck, lung, or breast can metastasize to the lymph nodes in the neck, causing them to swell.
• Tuberculosis (TB): TB can cause lymphadenitis, particularly in individuals from endemic areas or with compromised immune systems.
• HIV Infection: Acute HIV infection can present with lymphadenopathy among other symptoms.

Rare Diagnoses

• Cat-Scratch Disease: Caused by Bartonella henselae, this infection can lead to lymphadenopathy, typically after a cat scratch or bite.
• Toxoplasmosis: This parasitic infection can cause lymph node swelling, especially in immunocompromised individuals.
• Sarcoidosis: A systemic disease that can cause lymphadenopathy, among other symptoms, due to granulomatous inflammation.
• Kikuchi Disease: A rare, self-limiting condition that causes lymphadenitis, often presenting with fever and night sweats.

Each of these diagnoses has distinct features and risk factors that can help guide further evaluation and management. A thorough history, physical examination, and sometimes additional tests (like blood work, imaging, or biopsy) are necessary to determine the underlying cause of a swollen lymph node.