Differential Diagnosis for Large Cervical Lymphadenopathy, Neck Pain, and Fatigue

Single Most Likely Diagnosis

• Infectious Mononucleosis (Mono): Caused by Epstein-Barr virus (EBV), this condition is characterized by fever, sore throat, fatigue, and lymphadenopathy, particularly in the cervical region. The symptoms presented are classic for this diagnosis, making it the most likely.

Other Likely Diagnoses

• Tuberculosis (TB): TB can cause cervical lymphadenopathy, fever, and fatigue. Although less common in some regions, it remains a significant consideration, especially in areas with high TB prevalence or in individuals with risk factors for TB exposure.
• Lymphoma: Both Hodgkin and non-Hodgkin lymphoma can present with lymphadenopathy, fever, and fatigue. The cervical region is a common site for lymph node involvement in lymphoma.
• Reactive Lymphadenitis: This condition, often following a viral or bacterial infection, can cause lymph node enlargement, fever, and fatigue. It's a common and usually self-limiting condition.

Do Not Miss Diagnoses

• HIV Infection: Acute HIV infection can present with fever, lymphadenopathy, and fatigue. Missing this diagnosis could lead to delayed treatment and significant morbidity.
• Malignancy (e.g., Metastatic Cancer): Certain cancers, like head and neck cancers, can metastasize to cervical lymph nodes, causing lymphadenopathy. Early detection is crucial for treatment and prognosis.
• Cat-Scratch Disease: Caused by Bartonella henselae, this infection can lead to lymphadenopathy, particularly in the cervical region, along with fever and fatigue. It's essential to consider in individuals with a history of cat exposure.

Rare Diagnoses

• Kikuchi-Fujimoto Disease: A rare, self-limiting condition that causes lymphadenopathy, fever, and fatigue, more commonly seen in young women of Asian descent.
• Castleman Disease: A rare disorder that involves an overgrowth of cells in the lymphatic system, which can cause lymphadenopathy, fever, and fatigue.
• Sarcoidosis: Although more commonly associated with pulmonary symptoms, sarcoidosis can cause lymphadenopathy and systemic symptoms like fever and fatigue. It's a diagnosis of exclusion and requires histological confirmation.

Each of these diagnoses has a unique set of characteristics and risk factors. A thorough medical history, physical examination, and diagnostic tests (such as blood work, imaging, and potentially biopsy) are necessary to determine the underlying cause of the symptoms.