Endocrine Pathology Flashcards
Benign tumor of anterior pituitary cells
May be functional (hormone-producing) or nonfunctional (silent)
1. Nonfunctional tumors often present with mass effect.
i. Bitemporal hemianopsia occurs due to compression of the optic chiasm
ii. Hypopituitarism occurs due to compression of normal pituitary tissue
iii. Headache
Functional tumors present with features based on the type of hormone produced.
Prolactinoma presents as galactorrhea and amenorrhea (females) or as decreased
libido and headache (males); most common type of pituitary adenoma
Growth hormone cell adenoma
1. Gigantism in children - increased linear bone growth (epiphyses are not fused)
2. Acromegaly in adults
i. Enlarged bones of hands, feet, and jaw
ii. Growth ofvisceral organs leading to dysfunction (e.g., cardiac failure) iii. Enlarged tongue
3. Secondary diabetes mellitus is often present (GH induces liver gluconeogenesis)
4. Diagnosed by elevated GH and insulin growth factor-1 (IGF-1) levels along with lack of GH suppression by oral glucose
5. Treatment is octreotide (somatostatin analog that suppresses GH release), GH
receptor antagonists, or surgery.
ACTH cell adenomas secrete ACTH leading to Cushing syndrome
F. TSH cell, LH-producing, and FSH-producing adenomas occur, but are rare
What condition could this be
Pituitary adenoma
How does prolactinoma present
Galactorrhea
Amenorrhea (females)
Decreased libido and headache (males); most common type of pituitary adenoma
How is prolactinoma treated
Dopamine agonists (e.g., bromocriptine or cabergoline) to suppress prolactin production (shrinks tumor)
Surgery for larger lesions
How does acromegaly manifest in adults
Enlarged bones of hands, feet, and jaw
Growth of visceral organs leading to dysfunction (e.g., cardiac failure)
Enlarged tongue
How is pituitary adenoma diagnosed
Diagnosed by elevated GH and insulin growth factor-1 (IGF-1) levels along with lack of GH suppression by oral glucose
What are some causes of hypopituitarism
Pituitary adenomas (adults) or craniopharyngioma (children) - due to mass effect or pituitary apoplexy (bleeding into an adenoma)
Sheehan syndrome - pregnancy-related infarction of the pituitary gland
i. Gland doubles in size during pregnancy, but blood supply does not increase significantly; blood loss during parturition precipitates infarction.
ii. Presents as poor lactation, loss of pubic hair, and fatigue
Empty sella syndrome-congenital defect of the sella
i. Herniation of the arachnoid and CSF into the sella compresses and destroys the pituitary gland.
ii. Pituitary gland is “absent” (empty sella) on imaging
……… and …….. are made in the hypothalamus and then
transported via axons to the posterior pituitary for release.
ADH, oxytocin
What’s the function of ADH
ADH acts on the distal tubules and collecting ducts of the kidney to promote free water retention
What is the function of oxytocin
Oxytocin mediates uterine contraction during labor and release of breast milk (let-down) in lactating mothers
Cystic dilation of thyroglossal duct remnant
1. Thyroid develops at the base of tongue and then travels along the thyroglossal duct to the anterior neck.
2. Thyroglossal duct normally involutes; a persistent duct, however, may undergo cystic dilation.
Presents as an anterior neck mass
What condition could this be
Thyroglossal duct cyst
Persistence of thyroid tissue at the base of tongue
Presents as a base of tongue mass
What condition could this be
Lingual thyroid
What are some clinical features of hyperthyroidism
Weight loss despite increased appetite
Heat intolerance and sweating
Tachycardia with increased cardiac output
Arrhythmia (e.g., atrial fibrillation), especially in the elderly
Tremor, anxiety, insomnia, and heightened emotions
Staring gaze with lid lag
Diarrhea with malabsorption
Oligomenorrhea
Bone resorption with hypercalcemia (risk for osteoporosis)
Decreased muscle mass with weakness
Hypocholesterolemia
Hyperglycemia (due to gluconeogenesis and glycogenolysis)
What is hyperthyroidism
Increased level of circulating thyroid hormone
1. Increases basal metabolic rate (due to increased synthesis of Na+-K+ ATPase)
2. Increases sympathetic nervous system activity (due to increased expression of β1-adrenergic receptors)
What are some clinical features of Grave’s disease
Hyperthyroidism
Diffuse goiter - Constant TSH stimulation leads to thyroid hyperplasia and hypertrophy
What is the most common cause of hyperthyroidism
Graves’ disease
Autoantibody (IgG) that stimulates TSH receptor (type II hypersensitivity)
Leads to increased synthesis and release of thyroid hormone
1. Most common cause of hyperthyroidism
2. Classically occurs in women of childbearing age (20-40 years)
Clinical features include Hyperthyroidism and diffuse goiter - constant TSH stimulation leads to thyroid hyperplasia and
hypertrophy
3. Exophthalmos and pretibial myxedema
i. Fibroblasts behind the orbit and overlying the shin express the TSH receptor
ii. TSH activation results in glycosaminoglycan (chondroitin sulfate and hyaluronic acid) buildup, inflammation, fibrosis, and edema leading to exophthalmos and pretibial myxedema
What condition could this be
Graves’ disease
What are the laboratory findings in Graves’ disease
- ↑ total and free T4; ↓ TSH (free T3 downregulates TRH receptors in the anterior pituitary to decrease TSH release)
- Hypocholesterolemia
- Increased serum glucose
What the treatment for Graves’ disease
β- blockers
Thioamide
Radioiodine ablation
What is a potential fatal complication for Graves’ disease
Thyroid storm
1. Due to elevated catecholamines and massive hormone excess, usually in response to stress (e.g., surgery or childbirth)
2. Presents as arrhythmia, hyperthermia, and vomiting with hypovolemic shock
3. Treatment is propylthiouracil (PTU), β- blockers, and steroids.
i. PTU inhibits peroxidase-mediated oxidation, organification, and coupling steps of thyroid hormone synthesis, as well as peripheral conversion o f T4 to T3
What could cause a thyroid storm in Graves’ disease
Due to elevated catecholamines and massive hormone excess, usually in response
to stress (e.g., surgery or childbirth)
Presents as arrhythmia, hyperthermia, and vomiting with hypovolemic shock
Treatment is propylthiouracil (PTU), β- blockers, and steroids.
i. PTU inhibits peroxidase-mediated oxidation, organification, and coupling steps of thyroid hormone synthesis, as well as peripheral conversion o f T4 to T3
How do you treat a thyroid storm in Graves’ disease
Propylthiouracil (PTU)
β- blockers
Steroids
What are some types of hypothyroidism
Cretinism
Myxedema
Hypothyroidism in neonates and infants
Characterized by mental retardation, short stature with skeletal abnormalities, coarse facial features, enlarged tongue, and umbilical hernia
What condition could this be
Cretinism
1. Thyroid hormone is required for normal brain and skeletal development.
Causes include maternal hypothyroidism during early pregnancy, thyroid agenesis,
dyshormonogenetic goiter, and iodine deficiency.
1. Dyshormonogenetic goiter is due to a congenital defect in thyroid hormone production; most commonly involves thyroid peroxidase
What are some clinical features of myxedema
Clinical features are based on decreased basal metabolic rate and decreased sympathetic nervous system activity
1. Myxedema - accumulation of glycosaminoglycans in the skin and soft tissue
Results in a deepening of voice and large tongue
Weight gain despite normal appetite
Slowing of mental activity
Muscle weakness
Cold intolerance with decreased sweating
Bradycardia with decreased cardiac output, leading to shortness of breath and fatigue
Oligomenorrhea
Constipation
Hypercholesterolemia
What are the most common causes of myxedema
Iodine deficiency and Hashimoto thyroiditis
Other causes include drugs (e.g., lithium)
Surgical removal or radioablation of the thyroid
What are the various types of thyroiditis
Hashimoto thyroiditis
Subacute granulomatous (De Quervain) thyroiditis
Riedel fibrosing thyroiditis
What are some clinical features of Hashimoto thyroiditis
Initially may present as hyperthyroidism (due to follicle damage)
Progresses to hypothyroidism; ↓T4 and↑TSH
Antithyroglobulin and antithyroid peroxidase antibodies are often present (sign of thyroid damage)
Autoimmune destruction of the thyroid gland; associated with HLA-DR5
1. Most common cause of hypothyroidism in regions where iodine levels are adequate
Chronic inflammation with germinal centers and Hurthle cells (eosinophilic
metaplasia of cells that line follicles) is seen on histology
Increased risk for B-cell (marginal zone) lymphoma; presents as an enlarging thyroid gland late in disease course
What condition could this be
Hashimoto thyroiditis
Granulomatous thyroiditis that follows a viral infection
Presents as a tender thyroid with transient hyperthyroidism
Self-limited; rarely (15% of cases) may progress to hypothyroidism
What condition could this be
Subacute granulomatous thyroiditis
Chronic inflammation with extensive fibrosis of the thyroid gland
Presents as hypothyroidism with a ‘hard as wood,’ nontender thyroid gland
Fibrosis may extend to involve local structures (e.g., airway).
1. Clinically mimics anaplastic carcinoma, but patients are younger (40s), and malignant cells are absent
What condition could this be
Riedel fibrosing thyroiditis
Usually presents as a distinct, solitary nodule
1. Thyroid nodules are more likely to be benign than malignant.
131 I radioactive uptake studies are useful to further characterize nodules.
1. Increased uptake (‘hot’ nodule) is seen in Graves disease or nodular goiter.
2. Decreased uptake (‘cold’ nodule) is seen in adenoma and carcinoma; often warrants biopsy
Biopsy is performed by fine needle aspiration (FNA)
What condition could this be
Thyroid neoplasia