Dental infection or abscess: This is the most likely diagnosis given the location of the lymph node and the symptom of pain with chewing. The preauricular lymph node drains the area around the jaw and teeth, so an infection in this region could cause lymphadenopathy.

Parotid gland infection or inflammation: The preauricular lymph node is also close to the parotid gland, and infections or inflammation of this gland could cause lymphadenopathy and pain in the area.
Temporomandibular joint (TMJ) disorder: TMJ disorders can cause pain with chewing and potentially lead to lymphadenopathy in the preauricular region due to inflammation or infection.
Otitis externa or media: Infections of the outer or middle ear could cause lymphadenopathy in the preauricular region and pain with chewing if the infection spreads to involve the jaw or temporomandibular joint.

Lymphoma: Although less common, lymphoma could present with lymphadenopathy in any location, including the preauricular region. It's crucial to consider this diagnosis to ensure timely treatment if present.
Tuberculosis: TB can cause lymphadenopathy in any location and is a critical diagnosis not to miss due to its public health implications and the need for specific treatment.
Cat-scratch disease: This infection, caused by Bartonella henselae, typically presents with lymphadenopathy near the site of a cat scratch. Although less likely, it's a diagnosis that should be considered, especially if the patient has a history of cat exposure.

Sarcoidosis: This autoimmune disease can cause lymphadenopathy in various locations, including the preauricular region, although it is less common.
Kawasaki disease: This rare condition, primarily affecting children, can cause lymphadenopathy, among other symptoms, and is important to recognize due to its potential for serious complications if not treated promptly.
Actinomycosis: A rare bacterial infection that can cause lymphadenopathy and abscesses in the face and neck region, including the preauricular area.