Differential Diagnosis for Thyroid Scan Results
The thyroid scan results indicate a hot nodule in the left thyroid lobe with increased radiotracer uptake and a 24-hour uptake of 19%, which is within the normal range. Based on these findings, the following differential diagnoses can be considered:
- Single most likely diagnosis
- Toxic Adenoma: The presence of a hot nodule with increased radiotracer uptake and subclinical hyperthyroidism suggests a toxic adenoma, which is a benign tumor that produces excess thyroid hormone.
- Other Likely diagnoses
- Hyperfunctioning Thyroid Nodule: This diagnosis is similar to toxic adenoma, but it may not necessarily be a single adenoma. The nodule is hyperfunctioning, leading to increased thyroid hormone production.
- Multinodular Goiter with a Dominant Nodule: Although the scan shows a single large nodule, it is possible that there are other nodules present that are not visible on the scan. If the dominant nodule is hyperfunctioning, it could lead to subclinical hyperthyroidism.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Thyroid Cancer: Although the scan does not suggest malignancy, it is essential to consider the possibility of thyroid cancer, particularly if the nodule is large and has increased radiotracer uptake. A fine-needle aspiration biopsy may be necessary to rule out cancer.
- Thyroiditis: Inflammation of the thyroid gland (thyroiditis) can cause increased radiotracer uptake and hyperthyroidism. Although less likely, it is crucial to consider this diagnosis to avoid missing a potentially treatable condition.
- Rare diagnoses
- Struma Ovarii: This is a rare condition where thyroid tissue is present in the ovaries and can produce excess thyroid hormone. Although unlikely, it could be considered if other diagnoses are ruled out.
- Familial Thyroid Disorders: Certain genetic disorders, such as familial non-medullary thyroid cancer or multiple endocrine neoplasia, can increase the risk of thyroid nodules and cancer. These diagnoses are rare but should be considered if there is a family history of thyroid disorders.