Differential Diagnosis

The provided findings of mild tracer uptake in bilateral axillary lymph nodes and the left iliac chain are nonspecific, and a broad differential diagnosis should be considered. Here's a categorized approach to the differential diagnosis:

• Single most likely diagnosis:
  • Reactive lymph nodes: This is the most likely diagnosis given the nonspecific nature of the findings and the common occurrence of reactive lymph node changes in response to various stimuli, including infections, inflammation, or even recent vaccinations.
• Other Likely diagnoses:
  • Lymphoproliferative disorder: Although less common, lymphoproliferative disorders such as lymphoma could present with similar findings, especially if the disease is in its early stages or if it's a low-grade lymphoma.
  • Metastatic disease: Small metastases from a primary malignancy could also present with mild tracer uptake in lymph nodes, though the size of the nodes (up to 10mm and 12mm) might be on the smaller side for typical metastatic disease.
• Do Not Miss diagnoses:
  • Lymphoma (including Hodgkin lymphoma and non-Hodgkin lymphoma): Missing a diagnosis of lymphoma could have significant implications for patient outcomes, given the importance of early treatment.
  • Metastatic malignancy: Failing to consider and investigate for a primary malignancy with metastatic potential could lead to delayed diagnosis and treatment of a potentially curable cancer.
  • Tuberculosis or other granulomatous disease: Although less common in some regions, tuberculosis and other granulomatous diseases can cause lymph node uptake and have significant public health and treatment implications.
• Rare diagnoses:
  • Sarcoidosis: This is a systemic granulomatous disease that can affect lymph nodes and cause tracer uptake, though it's less common and typically presents with other systemic symptoms.
  • Castleman disease: A rare lymphoproliferative disorder that can present with lymph node enlargement and increased tracer uptake, often requiring specific diagnostic consideration.
  • Kikuchi-Fujimoto disease: A rare, self-limiting condition that causes lymphadenopathy, more commonly seen in young women, and can mimic lymphoma or other serious conditions.

Each of these diagnoses has a different set of implications for patient management and outcome, highlighting the importance of a thorough diagnostic workup to determine the underlying cause of the observed lymph node findings.