Viral Upper Respiratory Infection (URTI) with Reactive Lymphadenopathy: The presence of cold symptoms such as nasal congestion and dry cough, along with palpable lymph nodes, suggests a viral infection. The lymphadenopathy is likely a reactive response to the infection, which is common and usually resolves on its own.

Infectious Mononucleosis (Mono): Caused by Epstein-Barr virus (EBV), it can present with lymphadenopathy, particularly in the neck, and may be accompanied by symptoms similar to a cold. The absence of fever does not rule out this diagnosis.
Streptococcal Pharyngitis: Although the patient does not have a sore throat, streptococcal infections can cause lymphadenopathy. The recent onset of cold symptoms could be a viral co-infection or a precursor to a bacterial infection.
Allergic Rhinitis: Could cause nasal congestion and might be associated with some lymph node enlargement due to chronic antigen exposure, though this is less likely to cause significant palpable lymphadenopathy.

Lymphoma: Although less common, lymphoma can present with painless lymphadenopathy. It's crucial to consider this diagnosis, especially if the lymph nodes do not resolve with conservative management or if other systemic symptoms develop.
Tuberculosis (TB): Can cause lymphadenopathy, often in the neck, and may be accompanied by systemic symptoms like cough. The absence of fever and other symptoms does not rule out TB, especially in endemic areas or in individuals with risk factors.
HIV Infection: Acute HIV infection can present with lymphadenopathy and flu-like symptoms. Although the current symptoms are mild, HIV testing might be considered, especially if the lymphadenopathy persists or if there are risk factors for HIV exposure.

Toxoplasmosis: Can cause lymphadenopathy, particularly in immunocompromised individuals or those exposed to the Toxoplasma gondii parasite.
Cat-Scratch Disease (Bartonellosis): Caused by Bartonella henselae, transmitted through cat scratches. It can lead to lymphadenopathy, usually near the site of the scratch.
Kawasaki Disease: Although more common in children, it can cause lymphadenopathy along with other symptoms like fever, rash, and conjunctivitis. The absence of these other symptoms makes it less likely but not impossible in adults.
Sarcoidosis: A systemic disease that can cause lymphadenopathy among other symptoms. It's less likely given the acute onset of symptoms but could be considered if lymphadenopathy persists and other systemic symptoms appear.