Pituitary Adenoma
Such a TSH secreting pituitary adenoma is an uncommon cause for hyperthyroidism.
Pituitary Adenoma
- Q: What is seen on the sagittal MRI?
- Mass within the sella turcica of the sphenoid bone
- Pituitary adenoma — benign tumour of the anterior pituitary gland
- Q: Classic neurological/visual symptom?
- Bitemporal hemianopsia (loss of outer visual fields in both eyes)
Read this in Pathology Spot Exam Revision: Lymphoma, Adenoma, Appendicitis, FISH
Pituitary Adenomas
- These are benign tumors of anterior pituitary cells, classified by size (<1 cm = microadenoma ; 1 cm = macroadenoma ) and the hormone they secrete.
Read this in ENDOCRINE PATHOLOGY
What our notes say
- Such a TSH secreting pituitary adenoma is an uncommon cause for hyperthyroidism. (Chemical pathology and Endocrine pathology — Past Paper Questions & Answers)
- In acromegaly, it is typically caused by a GH-secreting pituitary adenoma producing excess GH autonomously. (END YEAR PP1 & PP2 2025 Physiology: MCQs for Medical School Exams)
- The vast majority of acromegaly cases arise from a GH-secreting pituitary adenoma; ectopic GHRH (A) is a rare cause. (Chemical Pathology: Endocrine Cases, Pituitary & Thyroid Q&A)
- Distinguishing histological feature of pituitary adenoma from normal tissue is (General Pathology MCQs: Fixatives, FNA, Endocrine & ARDS)
- This condition is most commonly caused by a functioning pituitary adenoma. (ENDOCRINE PATHOLOGY)
- Compression by a pituitary adenoma can lead to bitemporal hemianopia (due to compression of the optic chiasm), headache, hypopituitarism, and cranial nerve palsies (III, IV, VI) if the cavernous sinus is invaded. (ENDOCRINE PATHOLOGY)
Study material on Pituitary Adenoma
- ENDOCRINE PATHOLOGY
- Chemical pathology and Endocrine pathology
- Pathology Spot Exam Revision: Lymphoma, Adenoma, Appendicitis, FISH
- Chemical Pathology: Endocrine Cases, Pituitary & Thyroid Q&A
- ADRENAL NEOPLASMS — Adenoma vs Carcinoma
- Hypothalamic Hormones: Master Regulators of the Endocrine System
- Endocrine & Renal Pathology
- Year 3: Endocrine and Metabolic Pathology
Practice questions on Pituitary Adenoma
A patient experiences a sudden severe headache, bitemporal hemianopia, and acute hypopituitarism. MRI reveals hemorrhage into a pituitary adenoma. What is the diagnosis?
- Empty sella
- Craniopharyngioma
- Subarachnoid haemorrhage
- Pituitary apoplexy
Answer: D. Pituitary apoplexy is an acute complication of a pituitary adenoma, characterized by hemorrhage or infarction within the tumor. It presents with sudden severe headache, visual disturbances (bitemporal hemianopia), ophthalmoplegia, and acute hypopituitarism, often presenting with adrenal insufficiency. ---
Which of the following hormone levels would be expected in a patient with Cushing's disease (pituitary adenoma)?
- Low ACTH, high cortisol
- High ACTH, high cortisol
- Low ACTH, low cortisol
- High ACTH, low cortisol
Answer: B. Cushing's disease is caused by a pituitary adenoma secreting excess ACTH. This excess ACTH stimulates the adrenal glands to produce excessive cortisol. Therefore, both ACTH and cortisol levels are high. ---
The most common functioning pituitary adenoma is
- GH-secreting
- ACTH-secreting
- Prolactinoma
- TSH-secreting
Answer: C. Prolactinomas are the most common pituitary adenomas. ---
A TSH-secreting pituitary adenoma (thyrotropinoma) causes
- Central hypothyroidism with low TSH
- Hyperthyroidism with elevated TSH (inappropriately normal/high for the T4 level)
- Hyperthyroidism with suppressed TSH
- Normal thyroid function with elevated TSH
Answer: B. TSH-oma = rare (<1% of pituitary adenomas). Autonomous TSH secretion → hyperthyroidism (high T3/T4) but TSH is NOT suppressed (inappropriately normal or elevated). Key distinguishing point from Graves'/toxic nodule where TSH is suppressed. Treat with somatostatin analogues (octreotide) + surgery. ---
Which is a characteristic feature of pituitary adenomas?
- Cellular pleomorphism
- Cellular monomorphism and lack of reticulin network
- Perivascular invasion
- Extensive necrosis
Answer: B. Pituitary adenomas are typically characterized by uniform, monomorphic cells and a loss of the normal reticulin network. ---
In Cushing's disease (pituitary adenoma), cortisol on dexamethasone suppression testing is
- Suppressed by both low and high dose
- Not suppressed by either dose
- Not suppressed by low dose but IS suppressed by high dose
- Suppressed by low dose but not high dose
Answer: C. Pituitary adenoma retains partial feedback sensitivity. Ectopic ACTH and adrenal tumors = unsuppressed by either dose. Key distinguishing test. ---