What is a thyroglossal duct cyst?
Cystic dilation of thyrogossal duct remnant
- Presents as anterior neck mass
Wha is lingual thyroid?
Persistence of thyroid tissue at base of tongue
- Don't get embryological descent of thyroid through thyroglossal duct
- Presents as a base of tongue mass
What is Hyperthyroidism?
Increased level of circulating thyroid hormone
- Increase basal metabolic rate by increasing synthesis of Na/K ATPase
- Increases sympathetic nervous sytem activity due to expression of B1 adrenergic receptors
What are clinical features of hyperthyroidism?
- Weight loss despite increased appetite
- Heat intolerance and sweating
- Tachycardia with increased cardiac output
- Arrhythmia (esp. in elderly)
- Tremor, anxiety, insomnia, and heightened emotions
- Staring gaze with lid lag
- Diarrhea with malabsorption
- Bone resorption with hypercalcemia (can lead to osteoporosis)
- Decreased muscle mass with weakness
What is most common cause of hyperthyroidism?
- Autoantibody (IgG) that stimulates TSH receptors
- Leads to increased synthesis and release of thyroid hormone
- Occurs in women of childbearing age
What are clinical features of Graves Diseaes?
Exophthalmos and pretibial myxedema (due to IgG activation of TSH receptors at these sites causing production of excess glycosaminoglycans)
What are lab features of Graves Disease?
- Increased total and free T4
- Decreased TSH (T4 down regulates TRH receptors on anterior pituitary)
- Increased serum glucose
- "Scalloping" histology of thryoid follicles
What is the treatment for Graves disease?
Thioamide (blocks production of T4)
What is thyroid storm?
Feared Complication of Graves Disease
- Elevated catecholamines and massive hormone excess (stress)
- Arrhythmia, hyperthermia, and vomiting with hypovolemic shock
- Treted with PTU, Beta-blockers, and steroids
What is a multinodular goiter?
Enlarged thyroid gland with multiple nodules
- Due to relative iodine deficiency
- Usually nontoxic (euthyroid)
- Rarely, regions become TSH-independent ("toxic goiter")
What is Cretinism? What are its symptoms?
Hypothyroidism in neonates and infants
Short Stature with skeletal abnormalities
Coarse facial features
What are causes of Cretinism?
- Maternal hypothyroidism during early pregnancy
- Thyroid agenesis
- Dyshormonogenetic goiter
- Iodine deficiency
What is myxedema? Clinical features?
Hypothyroidism in older children or adults
- Myxedema (edema has "dough-like" consistency)
- Larynx --> deepening of voice
- Enlarged tongue
- Weight gain despite normal appetite
- Slowing of mental activity
- Muscle weakness
- Cold intolerance with decreased sweating
- Bradycardia with decreased cardiac output
What are causes of Myxedema?
Hashimoto Thyroiditis (autoimmune destruction of thryoid gland
Drugs (i.e. lithium)
Surgical removal or radioablation of thyroid
What is Hashimoto Thyroiditis?
Autoimmune destruction of thyroid gland
- Associated with HLA-DR5
What are clinical features of Hashimoto Thyroiditis?
Initially may present as hyperthyroidism (due to initial destruction of cells and abundant release of T4)
- Passes a point of normal thyroid regulation then:
- Progresses to hypothyroidism (decreased T4 and Increased TSH)
- Antithyroglobulin and antimicrosomal antibodies are often present (signs of thyroid damage)
- Chronic inflammation with formation of germinal centers and hurthle cells, histologically
What is Subacute (deQuervain) Granulomatous thyroiditis?
- Granulomatous thyroiditis that follows a viiral infection
- Presents as tender thyroid with transient hyperthyroidism
- Self-limited; does not progress to hypothyroidism
What is Reidel Fibrosing Thyroiditis?
- Chronic inflammation with extensive fibrosis of thyroid
- Presents as hypothyroidism with 'hard as wood' nontender thyroid gland
- Fibrosis may extend to local structures (i.e. airway)
--> Classically a young female
What is a 131I radioactive uptake study?
Completed to help diagnose thyroid nodules
- Increaed uptake of 131I seen in Graves or nodula goiter
- Decreased uptake of 131I seen in adenoma and carcinoma (warrants FNA - fine needle aspiration - biopsy)
What is a follicular adenoma?
Benign proliferation of follicles surrounded by a fibrous capsule
- Usually nonfunctional; rarely may secrete thyroid hormone
What are the four types of thyroid carcinomas?
Papillary Carcinoma (*Most Common* = 80%)
What is a major risk factor for papillary carcinoma?
Exposure to ionizing radiation in childhood
What are histological signs of papillary carcinoma?
Production of papillary structures
- Presence of "orphan annie-eyed" nuclei
- Presence of nuclear grooves
- Calcification of papillary architecture leads to psammoma bodies
Where does papillary carcinoma of the thyroid spread?
Cervical lymph nodes
- however, even with lymph node spread, there is an excellent prognosis
What is follicular carcinoma? Where does it metastesize to?
Malignant proliferation of follicles in the thyroid
- Surrounded by a fibrous capsule with invasion through capsule --> FNA cannot distinguish between follicular adenoma and follicular carcinoma
- Generally goes into blood (hematogenous metastesis)
What is medullary carcinoma?
- Malignant proliferation of parafollicular C cells
- High levels of calcitonin produced by tumor may lead to hypocalcemia
- Calcitonin often deposits within tumor as amyloid (localized amyloidosis)
What are familial cases of medullary carcinoma associated with?
Multiple Endocrine Neoplasia (MEN) 2A and 2B
--> RET oncogene
Detection of RET mutation warrants prophylactic thyroidectomy
What is anaplastic carcinoma?
Undifferentiated malignant tumor of thyroid
- Usually seen in elderly
- Often invades local structures leading to dysphagia or respiratory compromise
- poor prognosis
- Clinically similar to Reidels thyroiditis (which is seen in younger patients)