Thyroid Gland Pathology Flashcards
What are the cells lining the follicle?
Cuboidal or Columnar Epithelium
What do C cells secrete?
Calcitonin
What is the function of calcitonin
Calcitonin promotes absorption of calcium by the skeletal system and inhibits resorption of bone by osteoclasts
Thyrotoxicosis
Hyper metabolic state due to increased circulating levels of thyroid hormones due to any cause - often used interchangeably with hyperthyroidism
How does thyroiditis cause hyperthyroidism?
Destruction of the glands leads to release of pre-formed hormone that causes transient hyperthyroid episodes
What are the clinical features of hyperthyroidism?
- Increased BMR – soft warm flushed skin
- Heat intolerance and excess sweating
- Characteristic weight loss despite increased appetite
- Increased CO/tachycardia/palpitations
What tests can be used for Dx of hyperthyroidism?
- TSH levels - usually will be decreased
- T4 levels - usually increased
What is the TRH stimulation test used for?
Pituitary adenoma - normal rise in TSH after injection
of TRH excludes pituitary associated hyperthyroidism
Hypothyroidism
Hypometabolic state secondary to inadequate levels of thyroid hormones
What gender is more affected by hypothyroidism?
Females
What is the most common cause of hypothyroidism in 3rd world countries?
Iodine Deficiency
What is the most common cause of hypothyroidism in 1st world countries?
Chronic autoimmune thyroiditis (Hashimoto’s thyroiditis)
Cretinism
- Hypothyroidism in infants or early childhood
* Impaired development of skeletal muscles and CNS
Myxedema
- Adult hypothyroidism
- Gradual slowing of mental and physical activity
- Fatigue, lethargy, apathy, slowed speech
- Cold intolerance and reduced sweating
What lab findings with hypothyroidism show?
- Decreased T4
- Increased TSH
Hashimoto Thyroiditis
Characterized by gradual thyroid failure because of autoimmune destruction of the thyroid gland
What Ab will be found in Hashimoto thyroiditis?
- Thyroid Peroxidase Ab
- Thyroglobulin Ab
- TSH Receptor Ab
- Iodine Receptor Ab
- Diffusely enlarged gland
- Intact capsule
- Well demarcated from adjacent structures
- Cut surface is pale, yellow tan, somewhat nodular and firm
Hashimoto Thyroiditis
What cancer risk is increased with Hashimoto thyroiditis?
Non-Hodgkin B-cell Lymphoma
Subacute/Granulomatous DeQuervain Thyroiditis
- Viral or post-viral inflammatory response
- Viral antigens or virus-induced host tissue damage stimulates formation of cytotoxic T cells which then damage the thyroid follicular cells
What is the most common cause of thyroid pain?
Subacute/Granulomatous DeQuervain Thyroiditis
Subacute Lymphocytic Thyroiditis
- Usually in middle aged women and is painless
- Comes to clinical attention due to mild hyperthyroidism, goitrous enlargement of the thyroid or both
Riedel Thyroiditis
RARE - Extensive fibrosis involving the thyroid and contiguous neck structures with possible autoimmune etiology
What is the most common cause of endogenous hyperthyroidism?
Graves Disease
Graves Disease
Hyperthyroidism due to diffuse hyperfunctional enlargement of thyroid with signs: exophthalmos and pretibial myxedema
What are the Ab found in Graves disease?
Thyroid stimulating immunoglobulin - binds TSH receptor with agonist function and mimics action of TSH
What is increased radioactive iodine uptake with diffuse uptake on radio iodine scans indicative of?
Graves Disease
Goiter
Enlargement of the thyroid
Diffuse Nontoxic Goiter
- Vast majority of patients euthyroid
- Mass effect – large thyroid may press on trachea, esophagus and also cause cosmetic disfigurement
- Normal T4 and T3
Multinodular Goiter
- Asymmetric enlargement with numerous nodules
- Seen in older adults
- Evolvement from diffuse goiters over many years due to repeated episodes of hyperplasia and involution from cyclical stressors
Nodules in what patients are more likely to be neoplasia?
- Males
- Younger patients
Follicular Adenoma
Benign - well defined in tact capsule with small follicles that are tightly packed
Follicular adenoma with cells bearing abundant pink granular cytoplasm due to presence of abundant mitochondria.
Oxyphil Adenoma
What is the most common thyroid carcinoma?
Papillary Carcinoma
What are histologic characteristics of papillary carcinoma?
- Ground glass or Orphan Annie eyed nuclei
- Large oval nuclei
- Psamomma bodies
Are papillae see with FVPTC?
No - follicular variant papillary thyroid carcinoma presents with follicular architecture
What mutation is associated with papillary carcinoma?
RET
Follicular Carcinoma
- Second most common thyroid cancer
- Slowly enlarging painless nodule – cold on scintiscans
- Hematogenous metastasis to bone, lungs, liver etc
- Capsular or vascular invasion
- Neuroendocrine neoplasms derived from the parafollicular or C cells
- May secrete calcitonin or other polypeptide hormones like ACTH or VIP
- 70% sporadic, 30% familial or associated with MEN syndrome 2A or 2B
Medullary Carcinoma
What is deposited in medullary carcinoma?
Amyloid
Anaplastic Carcinoma
Undifferentiated tumors that are aggressive with poor prognosis - Usually the disease has spread beyond thyroid into adjacent structures of the neck at presentation
Thyroglossal Duct Cyst
- Most common clinically significant congenital anomaly
- Incomplete atrophy of the duct
- Presents at any age as a midline cyst or an anterior mass
A 49-year-old woman has had increasing cold intolerance, weight gain of 4 kg, and sluggishness over the past two years. A physical examination reveals dry, coarse skin and alopecia of the scalp. Her thyroid is not palpably enlarged. Her serum TSH is 11.7 UU/mL (ref range 0.4 -4.4 uu/ml) with thyroxine of 2.1 ug/dL (ref range 5-11 ug/dL). A year ago, anti-thyroglobulin and anti-microsomal autoantibodies were detected at high titer. Which of the following thyroid diseases is she most likely to have?
A) DeQuervain disease B) Papillary carcinoma C) Hashimoto thyroiditis D) Nodular goiter E) Graves disease
C) Hashimoto thyroiditis
A 40-year-old woman notes increasing enlargement and discomfort in her neck over the past week. She sees her physician, who palpates diffuse, symmetrical enlargement with tenderness in the region of the thyroid gland. Thyroid function tests show serum TSH of 0.8 mUU/mL (ref range 0.4 -4.4 UU/ml) and thyroxine of 14.9 ug/dL (ref range 5-11 ug/dl). The physician refers the patient to an endocrinologist, but the next available appointment is in 8 weeks. When the endocrinologist examines the patient, the thyroid is no longer palpable and there is no pain. Repeat thyroid function tests reveal a serum TSH of 3.8 UU/mL and thyroxine of 5.7 ug/dL. Which of the following thyroid diseases is most likely to produce these findings?
A) Nodular goiter B) Non-Hodgkin lymphoma C) DeQuervain disease D) Hashimoto thyroiditis E) Graves disease F) Riedel thyroiditis
C) DeQuervain disease
A 35-year-old woman has had insomnia for the past 4 months. She has also had episodes of diarrhea with up to 4 loose stools per day. On physical examination, she exhibits bilateral lid lag and wide staring gaze. Her outstretched hands demonstrate a fine tremor. On palpation of her neck, the thyroid gland does not appear to be enlarged and no masses are palpable. Laboratory studies show a serum TSH of 10.8 UU/mL (ref range 0.4-4.4 UU/ml) in association with a serum free thyroxine of 5.1 ng/dL (ref range 0.8-1.7 ng/dl). Which of the following is the most likely diagnosis?
A) Graves disease B) Pituitary adenoma C) Chronic thyroiditis D) Prior thyroidectomy E) Nodular goiter
B) Pituitary adenoma
A 30-year-old woman from Barcelona has noted enlargement of her neck over the past 4 months. On physical examination, she has a diffusely enlarged thyroid that is not painful to palpation. Her TSH level is 0.2 mU/L. A subtotal thyroidectomy is performed and histologically the tissue shows follicles with papillary infoldings lined by tall columnar cells. Which of the following is the most likely diagnosis?
A) Subacute granulomatous thyroiditis B) Papillary carcinoma C) Multinodular goiter D) Hashimoto thyroiditis E) Graves disease
E) Graves disease
