Reactive Lymphadenopathy: This is the most common cause of lymphadenopathy in children, often due to a viral upper respiratory infection. The absence of sore throat or fever and the presence of enlarged tonsils suggest a chronic or reactive process rather than an acute infection.

Infectious Mononucleosis: Although less common in young children, infectious mononucleosis (caused by Epstein-Barr virus) can present with lymphadenopathy and tonsillar enlargement without significant throat pain or fever initially.
Streptococcal Pharyngitis Carrier State: Some children can be carriers of streptococcal bacteria without symptoms of pharyngitis, potentially leading to lymphadenopathy and tonsillar enlargement.
Allergic Rhinitis: Chronic allergic rhinitis can cause lymphadenopathy due to persistent antigen exposure and immune response.

Lymphoma: Although rare, lymphoma is a critical diagnosis not to miss. It can present with painless lymphadenopathy, and the absence of systemic symptoms like fever does not rule out this diagnosis.
Tuberculosis: TB can cause cervical lymphadenopathy, especially in endemic areas or in children exposed to individuals with TB. It may not always present with systemic symptoms like fever.
HIV Infection: Children with HIV can present with lymphadenopathy and recurrent infections, including those affecting the tonsils.

Cystic Hygroma or Lymphangioma: These congenital anomalies can cause lymphadenopathy, particularly if they become infected or inflamed.
Kawasaki Disease: Although it typically presents with fever, Kawasaki disease can cause lymphadenopathy and should be considered in the differential diagnosis of unexplained lymph node enlargement in children.
Sarcoidosis: Extremely rare in young children, sarcoidosis can cause lymphadenopathy but is usually accompanied by other systemic symptoms.
Autoimmune Lymphoproliferative Syndrome (ALPS): A rare genetic disorder that affects the immune system, leading to lymphadenopathy and splenomegaly among other symptoms.