Differential Diagnosis for Multi-Nodular Goiter with Focal Increased Activity
Single Most Likely Diagnosis
- Toxic Multinodular Goiter: This condition is characterized by the presence of multiple nodules in the thyroid gland, with some nodules producing excess thyroid hormone, leading to hyperthyroidism. The 14% uptake and focal increased activity in the right upper thyroid lobe support this diagnosis, as it indicates autonomous function of the nodule.
Other Likely Diagnoses
- Follicular Adenoma with Increased Uptake: A benign thyroid tumor that can cause focal increased uptake on a thyroid scan. While less common than toxic multinodular goiter, it remains a plausible explanation for the findings.
- Hyperfunctioning Thyroid Nodule: A single nodule within the thyroid gland that produces excess thyroid hormone, leading to hyperthyroidism. The focal increased activity is consistent with this diagnosis.
Do Not Miss Diagnoses
- Thyroid Cancer (Especially Papillary or Follicular): Although less likely, thyroid cancer can present with a multi-nodular goiter and focal increased activity. It is crucial to consider this diagnosis to avoid missing a potentially life-threatening condition.
- Metastasis to the Thyroid: Rarely, metastatic disease from other cancers can involve the thyroid gland and cause focal increased activity on a scan. This diagnosis is critical not to miss due to its significant implications for patient management and prognosis.
Rare Diagnoses
- Struma Ovarii: A rare ovarian tumor that contains thyroid tissue, which can produce thyroid hormones and cause hyperthyroidism. This diagnosis would be unusual but could potentially explain the findings if the thyroid scan's focal activity is not actually originating from the thyroid gland.
- Thyroiditis (Subacute or Silent): Inflammation of the thyroid gland can cause transient hyperthyroidism and alterations in thyroid uptake. However, the pattern of multi-nodular goiter and focal increased activity is less typical for thyroiditis, making it a less likely consideration.