Differential Diagnosis
- Single most likely diagnosis
- NIFTP (Non-Invasive Follicular Thyroid Neoplasm with Papillary-like Nuclear Features) or a minimally invasive follicular or Hurthle-cell carcinoma: This diagnosis is most likely due to the presence of an NRAS mutation, which is commonly found in follicular-patterned neoplasms, and the cytology showing atypia of undetermined significance with Hurthle cells. The ThyroSeq interpretation also supports this diagnosis, indicating an intermediate to high probability of cancer or NIFTP.
- Other Likely diagnoses
- Benign follicular or Hurthle-cell adenoma: Although the molecular testing suggests a higher risk of malignancy, the possibility of a benign adenoma cannot be entirely ruled out, especially given the smooth margins and peripheral vascularity on ultrasound.
- Autoimmune thyroiditis (Hashimoto’s disease): The elevated thyroid peroxidase antibody and mildly positive thyroglobulin antibody confirm the presence of autoimmune thyroiditis, which is likely contributing to the patient's thyroid nodules and elevated thyroglobulin level.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Medullary thyroid carcinoma: Although the calcitonin level is less than 1 pg/mL, which makes this diagnosis unlikely, it is crucial to consider and rule out medullary thyroid carcinoma due to its aggressive nature and potential for familial occurrence.
- Papillary thyroid carcinoma: Although the cytology and molecular testing do not strongly support this diagnosis, papillary thyroid carcinoma can sometimes present with atypical features, and it is essential to consider this possibility to ensure timely and appropriate management.
- Rare diagnoses
- Follicular thyroid carcinoma with distant metastasis: Although the patient has no suspicious lymph nodes, and the thyroid hormone levels are normal, follicular thyroid carcinoma can occasionally present with distant metastasis, making it a rare but important consideration.
- Hurthle cell carcinoma: This is a rare subtype of follicular thyroid carcinoma, and the presence of Hurthle cells in the cytology makes it a consideration, although the molecular testing and clinical features do not strongly support this diagnosis.