1. Graves’ Disease
Autoimmune disorder which also presents with a possible neck protuberance (or goiter). This autoimmune reaction arises from a Type II hypersensitivity reaction to autoantibodies named Thyroid-stimulating Immunoglobulins (TSI’s) or Thyroid-stimulating Antibodies (TSabs) (McCance & Heuther, 2014, Chapter 22). These autoantibodies override the negative feedback mechanism, stimulate Thyroid Stimulating Hormone (TSH) on the receptor glands which lead to hyperplasia of the thyroid cells creating a goiter.
Diagnosed by physical examination (palpating nodules of the neck), fine needle aspiration, radioactive iodine uptake tests, and lab draws. Key features of Graves’ disease are exophthalmoses (protruding eyeballs), periorbital edema, and extraocular muscle weakness (which can also lead a to double vision) (McCance & Heuther, 2014, Chapter 22). Patients with very high levels of TSI’s can also develop subcutaneous swelling on the anterior portions of their legs along with indicated and erythematous skin called pretibial myxedema – Graves dermopathy.
Figure 22.9. Exopthalmos and Pretibial Myxedema (McCance & Heather, 2014, Chapter 22)
A. Exopthalmos
B. Pretibial Myxedema (note the lumpy tissue and discoloration)
Rationale: Our patient has hypertrophy of her thyroid lobes with firmness and tenderness which could be a goiter leading to the possible diagnosis of Graves Disease. Lab results showing decrease of T3 instead of an increase would also be used to rule it out as a diagnosis.
2. Thyroid Cancer
Thyroid cancer is the most common endocrine malignancy usually caused by exposure to ionizing radiation (particularly if this exposure comes when you are a child). T3 and T4 values tend to be normal and the disease is usually discovered by palpating a small nodule on the neck or finding a metastatic tumor in the regional lymph nodes, lungs, brain or bone (McCance & Heuther, 2014, Chapter 22). Due to the nature of the patient having a neck growth this would be a diagnosis that should be considered.
Diagnosed by fine needle aspiration. Drawing thyroid levels could be used to exclude other diagnoses since the T3 and T4 tend to be in the normal range for these patients. Treatment for carcinoma’s is controversial since the mortality rate is low no matter what treatment is chosen. Most will need surgical intervention (near-total or total thyroidectomy), post operative ionizing radiation and levothyroxine to replace the thyroid hormone and suppress TSH on the tumor cells.
Rationale: Because thyroid cancer is the most common endocrine malignancy it would be one of the first diagnoses to be considered when dealing with abnormal thyroid levels. Because our patients T3 and T4 levels are not normal it would indicate that this is not the case. The lack of exposure to radiation in the history and no change in her voice, swallowing or breathing would be indications that her nodule is not an impinging tumor. Her needle biopsy showing epithelial cells with cancerous characteristics would be a big indicator to think thyroid cancer. Further testing needed to rule this out.
3. Hypothyroidism
The most common disorder of thyroid function, affects 0.1-0.2% of the US, and is more common in women and the elderly (McCance & Heather, 2014, Chapter 22). Primary hypothyroidism (the more common of the two) is a result of low thyroid hormone (TH) produced by the thyroid gland while Secondary hypothyroidism is due to the pituitary’s inability to produce enough thyroid stimulating hormone (TSH) or thyrotropin releasing hormone (TRH).
Figure 22.10. Mechanisms of Primary and Central (Secondary) Hypothyroidism (McCance & Heather, 2014, Chapter 22)
Diagnosis would include documentation of symptoms (affects all body systems), measuring TSH and TH (expect to see increased TSH levels and decreased TH levels), checking for pituitary issues which would cause decreased TSH levels (McCance & Heather, 2014, Chapter 22). Treatment includes the use of hormone therapy (specifically levothyroxine) where the amount would depend on several factors like age, duration, and severity of symptoms.
Rationale: Being the most common thyroid disorder in general patients symptoms would lead us in this direction before any other along with the fact that she is elderly and a women. Lab results of low thyroid hormone and increased levels of TSH would continue to support our theory of hypothyroidism. The needle biopsy also reveals immune cells and macrophages which would push us to look a bit further into this diagnosis.
4. Hashimoto Disease/ Autoimmune Thyroiditis
The most common cause of hypothyroidism in the United States and leads to a gradual inflammatory destruction of thyroid tissue (McCance & Heather, 2014, Chapter 22). Major Histocompatibility Complex (MHC) antigens play a big part here and are different than the antigens found in Graves disease. Tissue destruction in Hashimoto is caused by the presence of many autoimmune cells including auto-reactive T lymphocytes, natural killer cells and inflammatory cytokines leading to apoptosis of the thyroid cells
Our diagnosis criteria is met for hypothyroidism but also includes the presence of thryroperoxidase and thyroglobulin antibodies (McCance & Heather, 2014, Chapter 22). Treatment is based on symptoms and requires thyroid hormone treatment.
Rationale: Our patient meets all of the criteria for hypothyroidism but also has the presence of some macrophages, lymphocytes, immune cells in the needle biopsy which are all involved in the inflammatory response to an autoimmune disorder. Hypertrophy of the thyroid lobes with tenderness is indicative of goiter formation which would also be expected in a patient with Hashimoto disease. Lastly the most indicative to this diagnosis is the fact that the patients thyroglobulin antibodies are vastly increased.
References:
McCance, K. L., & Heuther, S. E. (2015). Pathophysiology: The biological basis for disease in adults and children (8th ed.). St. Louis, MO: Mosby.