Differential Diagnosis for Thyroid Nodules
Single Most Likely Diagnosis
- Multinodular Goiter: This diagnosis is the most likely due to the presence of multiple subcentimeter nodules and heterogeneous thyroid parenchyma. The TI-RADS classification of the nodules, with one being TI-RADS 2 (benign) and the other TI-RADS 4 (suspicious), also supports this diagnosis as multinodular goiter can have a mix of benign and potentially malignant nodules.
Other Likely Diagnoses
- Thyroid Adenomas: These are common benign thyroid tumors that could explain the presence of the 1.4 cm right mid complex nodule (TI-RADS 2) and the 1.1 cm left mid hypoechoic nodule (TI-RADS 4), especially if the latter undergoes further evaluation (e.g., biopsy) that rules out malignancy.
- Hashimoto Thyroiditis: This autoimmune condition can cause heterogeneous thyroid parenchyma and the formation of nodules. While it's more commonly associated with hypothyroidism and specific ultrasound features like hypoechogenicity of the parenchyma, it could be considered in the differential, especially if there are clinical or laboratory findings suggestive of autoimmune thyroid disease.
Do Not Miss Diagnoses
- Papillary Thyroid Carcinoma: Although the TI-RADS 4 nodule has a lower suspicion of malignancy than a TI-RADS 5, papillary thyroid carcinoma is a common thyroid malignancy that can present as a hypoechoic nodule. Missing this diagnosis could have significant consequences, making it a "do not miss" diagnosis.
- Medullary Thyroid Carcinoma: This rare malignancy can also present as a nodule within the thyroid and has a significant genetic component. While less common than papillary thyroid carcinoma, its potential for aggressive behavior and the importance of early detection place it in the "do not miss" category.
Rare Diagnoses
- Anaplastic Thyroid Carcinoma: A very aggressive and rare form of thyroid cancer. It typically presents in older individuals and is associated with a poor prognosis. The presence of a rapidly growing nodule or significant symptoms would raise suspicion for this diagnosis.
- Metastatic Disease to the Thyroid: Rarely, cancers from other parts of the body can metastasize to the thyroid gland, presenting as one or more nodules. This would be considered in patients with a known history of cancer or in the presence of multiple unusual features on imaging.