Endocrine Flashcards
Regarding pituitary adenoma, which is false? (September 2013, March 2016)
a. Associated with MEN 2
b. Large macroadenomas tend to invade the cavernous sinus
c. Less likely to constrict the ICA than meningioma
d. Pituitary macroadenomas cause bitemporal hemianopia
e. Pituitary adenomas can cause galactorrhoea
Pituitary macroadenomas:
o Most common suprasellar mass in adults
o Defined as pituitary adenomas >10mm
o Twice as common as pituitary microadenomas
Clinical presentation:
Local mass effect on structures e.g. the optic chiasm
Hormonal imbalance
Symptoms of hypopituitarism from compression
Rarely: pituitary apoplexy
Optic chiasm compression
- May be contacted, elevated or compression of the central part of the chiasm
- Central chiasm covers the fibres for the nasal retina
- In prefixed or postfixed chiasms (anterior or posterior to the pituitary fossa), there may be variable visual symptoms
Cavernous sinus invasion:
- Invasive growth & extension into the cavernous sinus seen w some adenomas
- More common in prolactin secreting tumours
• Circulating levels of prolactin increase when the adenoma gains access to the sinus
- Adenomas involving the sinus are difficult to resect
- Compression of cranial nerves: 1-14% - Most commonly occulomotor nerve
- Can encase the cavernous ICA
• <90 degrees of encasement suggests the cavernous sinus is not involved
• >270 degrees of encasement makes invasion almost certain
ANSWER: Pituitary adenomas are associated w MEN 1, not MEN 2a/b
What is the rarest presentation of a pituitary microadenoma? (March 2014)
a. Non-functioning
b. TSH secreting
c. ACTH secreting
d. FSH and LH secreting
e. Prolactin secreting
Incidence of functional status of a pituitary adenoma: o Non functioning ~ 35% o Functioning ~ 65% - Prolactin secreting – 30% - Growth hormone secreting – 15% - ACTH – 6% - TSH – 1% - FSH and LH - 10%
ANSWER: Thyrotroph microadenomas are the least common
What is the most common hormone secreted by pituitary microadenomas? (March 2017)
a. Prolactin
ANSWER: Prolactin is the most common hormone secreted by functioing pituitary microadenomas
What is most likely to be overproduced in an empty sella? (August 2016)
a. Prolactin
b. Growth hormone
c. ACTH
d. Thyrotropin
Empty sella
o Common incidental finding – sella largely empty of tissue and at least a little expanded. 20% of the population
o Associated w benign intracranial HTN
Pathology:
Primary -
• Herniation of the arachnoid space into the pituitary fossa through a deficient diaphragm
• More likely to occur in cases of intracranial HTN, however can be seen w/out
• More common in overweight females, or women w multiple pregnancies
• May cause visual symptoms or result in hyperprolactinaemia due to the interruption of inhibitory hypothalamic inputs
Secondary -
• Mass (e.g. pituitary macroadenoma) enlarges the sella & is then surgically removed or infarcts
• Causes a loss of pituitary function
ANSWER: Prolactin is most likely to be overproduced in an empty sella
Regarding craniopharyngioma, which is false? (September 2013)
a. Arises from the pituitary fossa
b. In a child, the lesion is lobulated and well defined
c. There are two peaks of incidence, in childhood and in mid-adulthood
d. It is usually calcified in childhood
e. Solid in adults
Craniopharyngioma
o WHO Grade I neoplasms which typically arise in the sellar/suprasellar region
- Can occur anywhere along the infundibulum, from the floor of the 3rd ventricle to the pituitary gland
- 75% have involvement of the sella & infrasellar spaces, however the lesions are predominantly suprasella in location (20% purely suprasella; <5% purely intrasella). Rare ectopic locations: intraventricular, nasopharynx, posterior fossa & extension down the cervical spine
o Derived from Rathke cleft (Rathke pouch remnants). Previously thought to derive from squamous cells of the craniopharyngeal duct
Adamantinomatous type (90%):
- Paediatric type, ages 10-14 - Equal M=F - Visual symptoms less common at presentation (20%)
Pathology:
• Reticular epithelial cells which resemble the enamel pulp of developing teeth
• Single or multiple cysts filled w thick, proteinaceous fluid, blood products +/- cholesterol (machinery oil consistency) - Ameloblastomas of the suprasellar region
• Characterised by ‘wet keratin nodules’
• Calcification in 90%
Imaging features:
• Lobulated contour w multiple cystic lesions
• Solid components do not predominate
• 90% calcified
• May be large, extend into the 3rd ventricle and/or encase vessels - Often adherent to adjacent structures
Papillary (20%)
- Seen almost exclusively in adults - Visual changes in 80% at presentation (more common)
Pathology:
• Formed of masses of metaplastic squamous cells - “Wet keratin’ is absent
• Cysts can form, but are not the predominant feature - More solid appearing tumour
• Calcification rare
Imaging features:
• Solid lesions – may contain a few cysts
• More spherical in contour
• Displace adjacent structures rather than encasing them
ANSWER: While paediatric craniopharyngiomas have a lobulated contour, they are usually poorly defined & may be adherent to adjacent structures and encase vessels
Which is true regarding craniopharyngioma? (March 2017)
a. Adamantinomatous is usually in adults
b. Papillary is usually in children
c. Craniopharyngioma usually has calcification and does not enhance
ANSWER: All options are false.
Precocious puberty is associated with all except: (March 2014)
a. Craniopharyngioma
b. Ovarian cyst
c. Adrenocortical carcinoma
Causes of precocious puberty:
o Central precocious puberty:
- Idiopathic
- Hypothalamic hamartoma
- Tumour: astrocytoma, cranipharyngioma, pituitary adenoma
- Congenital disorder: hydrocephalus, myelomeningocoele, arachnoid cyst
- Acquired: radiation, chemotherapy, post head trauma or post infection
o Peripheral precocious puberty:
- Ovarian tumour:
• Oestrogen secreting: granulosa cell, functional cyst
• Androgen secreting: sertoli-leydig cell, arrhenoblastoma (contrasexual)
- Adrenal cause:
• Congenital adrenal hyperplasia
• Cushing syndrome (contrasexual)
• Neoplasm: oestrogen or androgen secreting adenoma or carcinoma
- Exogenous sex hormones: contraceptives, skin creams, anabolic steroids
- McCune Albright syndrome
- Longstanding hypothyroidism
o Variants of normal pubertal development
ANSWER: All three options have been implicated in precocious puberty. The ovarian cyst would have to be a functional cyst. Adrenocortical carcinoma is very uncommon in children (peak age of onset 50 years)
Regarding tumours of the sella region, which is false? (September 2013)
a. Meningiomas are more likely to constrict the ICA than pituitary macroadenoma
b. Arachnoid cyst displaces the stalk anteriorly
c. A normal sized sella favours meningioma rather than a macroadenoma
d. Large macroadenomas invade the cavernous sinus
• Meningiomas of the cavernous sinus often constrict the cavernous ICA
o Pituitary macroadenomas can encase the ICA (>30% considered encasement), however do not typically cause narrowing
• Macroadenomas often expand the sella before growing superiorly into the suprasella recess
ANSWER: All options are true
Which will not result in diabetes inspidus? (March 2015)
a. Treatment with desmopressin
b. Head trauma
c. Sarcoid of the pituitary stalk
d. Lymphocytic hypophysitis
e. TB meningitis
Diabetes insipidus
o Deficiency (central/hypothalamic) or resistance (peripheral/nephrogenic) to ADH/vasopressin
- Causes polyuria and polydipsia
Causes of central diabetes insipidus:
- Trauma - Neurosurgery - Malignancy of the suprasellar region or stalk: craniopharyngioma, germinoma, metastases - Autoimmune e.g. sarcoidosis, LCH, IgG4 - Infection e.g. tuberculosis - Pregnancy - Familial - Idiopathic - Lymphocytic hypophysitis of the posterior pituitary (rare). Anterior gland more commonly involved, mimics a pituitary adenoma
Causes of peripheral DI:
- Long term lithium use (15%) - Metabolic (hypokalaemia, hypercalcaemia) - Chronic renal disease - Pregnancy - Congenital renal insensitivity to vasopression
Management:
- Desmopressin can be used to treat central DI
ANSWER: Treatment with desmopressin – this is the current standard management
What is the most likely cause of post-partum pituitary dysfunction? (March 2016)
a. Lymphocytic hypophysitis
Lymphocytic hypophysitis:
o Non-neoplastic inflammatory condition of the pituitary gland
- Related to orbital pseudotumour and Tolosa-Hunt
Epidemiology:
- More common in women - Post-partum or third trimester of pregnancy
Clinical presentation:
- Anterior pituitary (lymphocytic adenohypophysitis)
• Most common
• Mimics a pituitary adenoma
• Endocrine and hormone deficits
• Mass effect on the adjacent structures, including the optic chiasm
- Posterior pituitary (lymphocytic infundibular panhypophysitis)
• Rare
• Diabetes insipidis
Associations:
- Auto-immune conditions: autoimmune thyroiditis, pernicious anaemia - Monoclonal antibody drugs e.g. ipilmumab
Pathology:
- Infiltration of the pituitary stalk w lymphocytes
- Paucity of plasma cells & granulomas - Separate pathology to IgG4 disease & sarcoidosis
ANSWER: Lymphocytic hypophysitis is more common in females, particularly post partum or in the 3rd trimester of pregnancy
Regarding Hashimoto thyroiditis, which is true? (September 2013)
a. Rare cause of hypothyroidism
b. Rare cause of hyperthyroidism
c. Rare cause of goiter
d. Rarely malignant
e. No measurable antibodies
Hashimoto disease
o Autoimmune thyroiditis resulting in parenchymal destruction & progressive thyroid failure
- Most common cause of hypothyroidism in regions w/out endemic iodine deficiency
- Transient hyperthyroidism early in the disease course
Epidemiology:
- Most prevalent ages 45-65 - 10-20:1 female predominance
Pathology:
- Anti-thyroid antibodies
• Occurs secondary to a loss of self tolerance to thyroid antigen
• 40% concordance in monozygotic twins.
- Anti-bodies target thyroglobulin & thyroid peroxidase
- Injury mediated by CD8+ cytotoxic T cells
• Progressive loss of thyroid epithelium
• Mononuclear cell infiltration
• Fibrosis
Macro:
- Diffusely enlarged thyroid w pale parenchyma & an intact capsule
o Assoc w other autoimmune conditions such as DMI, autoimmune adrenalitis (Addison’s disease), SLE & Sjogrens
ANSWER: Hashimoto thyroiditis is rarely malignant
Which is least likely concerning thyroid disorders? (March 2014)
a. Antibodies in Hashimoto thyroiditis are to TSH
b. Subacute thyroiditis has seasonal variation due to the association with viral infection
c. Patients with Grave disease have low TSH levels
d. Simple goitre is associated with cassava consuming population
e. Plummer syndrome is due to a toxic nodule in a multinodular goitre
Hashimoto disease
o Occurs secondary to loss of self tolerance to thyroid antigens (T cell response & protein tryosine phosphatase)
o Circulating autoantibodies to thyroglobulin & thyroid peroxidase - CD8+ activation
o Injury characterised by progressive thyroid epithelium depletion, mononuclear cell infiltration and fibrosis of the thyroid
Assoc populations w endemic simple goitre have higher levels of consumption of soy beans, cassava and cruciferous vegetables
A toxic nodule within a goitre is referred to as Plummer syndrome
ANSWER: Hashimoto disease is not assoc w TSH autoantibodies – antibodies are directed against thyroglobulin & thyroid peroxidase
Which is true regarding Graves disease? (August 2014)
a. Most common in elderly women
b. TSH can distinguish between toxic adenoma and Graves disease
c. Associated with thyroglobulin antibody
Graves disease:
o Autoimmune thyroid disease
o Most common cause of thyrotoxicosis (85%)
Epidemiology:
- Strong female predilection (5:1)
- Middle age
Presentation:
- Thyrotoxicosis - Pre-tibial myxedema (2%) - Thyroid acropachy (1%) - Graves opthalmopathy (20-25%) - Encephalopathy assoc w autoimmune thyroid disease (EAATD) (rare)
Pathology:
- Antibody directed at the TSH receptor, causing overproduction of T3 and T4 - Thyroid receptor antibodies TSI, TGI, TBII - Diffuse, fleshy glandular enlargement - Micro: plump follicular cells hyperplastic follicles, evidence of colloid resorption. Scalloping of the apical membrane and variable follicle collapse/exhaustion
ANSWER: TGI (thyroglobulin antibody) is seen in 30% of patients w Graves disease. Both toxic adenoma & Graves disease have low TSH.
What is the most common type of thyroid cancer? (September 2013)
a. Papillary
b. Medullary
c. Anaplastic
d. Follicular
e. Hurthle cell
- Papillary: 60-80%
- Follicular: 10-20%
- Medullary: 5%
- Anaplastic: 1-2%
- Lymphoma: 2-5%
- Thyroid metastases: 1%
ANSWER: Papillary is the most common type of thyroid cancer
Which subtype of thyroid carcinoma is most likely to have lymphadenopathy? (March 2016)
a. Papillary
b. Anaplastic
c. Medullary
d. Follicular
ANSWER: Papillary is most likely to have nodal metastases
