Periodic Fever, Aphthous Stomatitis, Pharyngitis, and Adenitis (PFAPA) Syndrome: This condition is characterized by recurrent episodes of fever, often accompanied by other symptoms such as aphthous stomatitis, pharyngitis, and adenitis, occurring at regular intervals, typically every 3-6 weeks. It's a common cause of periodic fever in children.

Autoinflammatory Disorders (e.g., Familial Mediterranean Fever): These are genetic disorders that lead to recurrent episodes of fever and inflammation, often with other systemic symptoms. While less common than PFAPA, they are important to consider in the differential diagnosis.
Infectious Causes (e.g., Recurrent Urinary Tract Infections, Sinusitis): Certain infections can cause periodic fever if they recur at regular intervals due to an underlying anatomical or functional issue.
Immunodeficiency: Children with immunodeficiency may experience recurrent infections, leading to periodic fever.

Malignancies (e.g., Lymphoma, Leukemia): Although rare, malignancies can present with periodic fever among other symptoms. Missing these diagnoses can have severe consequences.
Tuberculosis: Especially in endemic areas, tuberculosis can cause periodic fever and is crucial not to miss due to its public health implications and the need for specific treatment.
Endocarditis: Infective endocarditis can present with intermittent fever and is a medical emergency.

Hyper-IgD Syndrome (Mevalonate Kinase Deficiency): A rare autoinflammatory disorder characterized by recurrent episodes of fever, often accompanied by other symptoms like abdominal pain, arthralgia, and rash.
TNF Receptor-Associated Periodic Syndrome (TRAPS): Another rare autoinflammatory disorder that presents with recurrent fever episodes, often with additional symptoms such as abdominal pain, rash, and conjunctivitis.
Cyclic Neutropenia: A rare condition where the neutrophil count periodically drops, leading to recurrent infections and fever.