Differential Diagnosis for Enlarged Left Posterior Auricle Lymph Node, Elevated WBC and Neutrophils, and Thyroid Nodule

• Single Most Likely Diagnosis
  • Infectious Thyroiditis or Subacute Thyroiditis: This condition can cause thyroid nodules, elevated WBC and neutrophils due to inflammation, and could potentially lead to reactive lymphadenopathy, including an enlarged lymph node near the auricle due to its proximity to lymphatic drainage pathways.
• Other Likely Diagnoses
  • Thyroid Cancer with Metastasis: Although less common, thyroid cancer (especially papillary thyroid carcinoma) can present with a thyroid nodule and metastasize to local lymph nodes, including those in the neck and potentially affecting nodes near the auricle due to aberrant lymphatic drainage.
  • Reactive Lymphadenitis: This could be due to a local infection (e.g., otitis externa, mastoiditis) or a systemic infection causing lymph node enlargement, elevated WBC, and neutrophils. The thyroid nodule might be an incidental finding.
  • Granulomatous Disease (e.g., Sarcoidosis, Tuberculosis): These conditions can cause lymphadenopathy, thyroid nodules (due to granulomatous involvement of the thyroid), and elevated inflammatory markers.
• Do Not Miss Diagnoses
  • Metastatic Malignancy to the Thyroid and Lymph Nodes: Although rare, malignancies from other primary sites can metastasize to the thyroid gland and to lymph nodes, including those near the auricle. Missing this diagnosis could have significant implications for treatment and prognosis.
  • Lymphoma: Both Hodgkin and non-Hodgkin lymphoma can present with lymphadenopathy, and some types may involve the thyroid gland directly or indirectly, leading to nodules. Early diagnosis is crucial for effective treatment.
• Rare Diagnoses
  • Kimura Disease: A rare, chronic inflammatory disorder that can cause lymphadenopathy, particularly in the head and neck region, and is often associated with eosinophilia. It might also present with a thyroid nodule, although this is less common.
  • Castleman Disease: A rare disorder that can cause lymphadenopathy and may be associated with systemic symptoms, including elevated inflammatory markers. Thyroid involvement is not typical but could be considered in the differential diagnosis of a thyroid nodule in this context.