Differential Diagnosis for Bilateral Axillary Lymphadenopathy with Leukocytosis

Single Most Likely Diagnosis

• Infectious Mononucleosis (Mono): Caused by Epstein-Barr virus (EBV), it often presents with lymphadenopathy, including axillary nodes, fever, sore throat, and fatigue, along with leukocytosis. The presence of bilateral axillary lymphadenopathy and an elevated white blood cell count makes this a plausible initial consideration.

Other Likely Diagnoses

• Lymphoma: Both Hodgkin and non-Hodgkin lymphoma can present with lymphadenopathy, including axillary lymph nodes, and systemic symptoms such as fever and weight loss. Leukocytosis may be present, especially in more aggressive forms.
• Breast Cancer: Although more commonly associated with unilateral axillary lymphadenopathy, in advanced stages, breast cancer can cause bilateral axillary lymph node involvement. Leukocytosis might be seen due to tumor-related inflammation or metastasis.
• Cat-Scratch Disease: Caused by Bartonella henselae, this condition typically presents with lymphadenopathy near the site of the cat scratch, but it can occasionally be more widespread, including axillary nodes, and is accompanied by systemic symptoms like fever.

Do Not Miss Diagnoses

• Tuberculosis (TB): Although less common in some regions, TB can cause lymphadenopathy, including in the axillae, along with systemic symptoms like fever, night sweats, and weight loss. Leukocytosis may be present. Given its potential for severe consequences if untreated, it's crucial not to miss this diagnosis.
• HIV Infection: Acute HIV infection can present with lymphadenopathy, including axillary nodes, along with fever, rash, and other flu-like symptoms. An elevated white blood cell count can be seen. Early diagnosis of HIV is critical for effective management and prevention of long-term complications.
• Sarcoidosis: This autoimmune disease can cause lymphadenopathy in various locations, including the axillae, along with systemic symptoms. While less likely to cause significant leukocytosis, its potential for multi-organ involvement makes it a diagnosis not to be missed.

Rare Diagnoses

• Castleman Disease: A rare disorder that involves an overgrowth of cells in the lymphatic system, which can lead to lymphadenopathy, including in the axillae. It can be associated with systemic symptoms and leukocytosis.
• Kikuchi-Fujimoto Disease: A rare, self-limiting condition that causes lymphadenopathy, typically in the cervical region but can involve axillary nodes, along with fever and leukocytosis.
• Silicone Implant Illness: In individuals with breast implants, especially those with silicone implants, a condition known as silicone implant illness can cause axillary lymphadenopathy among other symptoms, potentially accompanied by leukocytosis.

Each of these diagnoses requires careful consideration of the patient's history, physical examination, and additional diagnostic tests to determine the underlying cause of bilateral axillary lymphadenopathy with leukocytosis.