Differential Diagnosis for Mildly Enlarged Hypermetabolic Mediastinal and Hilar Lymph Nodes with MGUS

• Single Most Likely Diagnosis
  • Reactive lymph nodes: This is the most likely diagnosis given the mild enlargement and the presence of MGUS, which can cause a reactive lymph node response. The hypermetabolic activity can be seen in reactive nodes due to inflammation or infection.
• Other Likely Diagnoses
  • Lymphoma (e.g., Hodgkin lymphoma, non-Hodgkin lymphoma): Although less common, lymphoma can present with mildly enlarged lymph nodes and hypermetabolism on imaging. The presence of MGUS increases the risk of lymphoma.
  • Sarcoidosis: This is a systemic granulomatous disease that can cause lymph node enlargement and hypermetabolism. It can be associated with MGUS in some cases.
  • Infection (e.g., tuberculosis, fungal infections): Infectious diseases can cause lymph node enlargement and hypermetabolism, especially in immunocompromised patients or those with underlying conditions like MGUS.
• Do Not Miss Diagnoses
  • Lymphoproliferative disorders (e.g., Waldenström's macroglobulinemia): These disorders can present with lymph node enlargement and hypermetabolism, and the presence of MGUS increases the risk. Missing this diagnosis can lead to delayed treatment and poor outcomes.
  • Mediastinal germ cell tumors: Although rare, these tumors can present with lymph node enlargement and hypermetabolism. They are more common in young men and can be aggressive if not treated promptly.
• Rare Diagnoses
  • Castleman disease: This is a rare lymphoproliferative disorder that can cause lymph node enlargement and hypermetabolism. It can be associated with MGUS and other systemic symptoms.
  • Rosai-Dorfman disease: This is a rare histiocytic disorder that can cause lymph node enlargement and hypermetabolism. It can be associated with systemic symptoms and MGUS in some cases.