Endocrine System for NEET PG Pathology: Graves, Hashimoto, Thyroid Cancers, Diabetes, Hyperparathyroidism, Addison, Cushing, Phaeochromocytoma, MEN

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🎯 Exam priority: High. Expect: the commonest thyroid cancer and its spread, medullary carcinoma and calcitonin/RET, Graves antibody, Hashimoto histology and lymphoma risk, subacute thyroiditis giant cells, diabetes cut-offs and islet amyloid, parathyroid adenoma, Addison causes, Cushing disease vs ectopic ACTH, phaeochromocytoma 10% facts, and MEN components.

CBME mapping: PA 31.1–31.10. Diabetic kidney is in article 21; amyloid in article 6; pancreatic NETs in article 17.

Thyroid, islets, parathyroid, adrenal and MEN. Drawn by TrackNation.

Thyroid Function and Thyroiditis

• Simple goitre: non-cancerous thyroid enlargement without hormone excess, deficiency or inflammation. Iodine deficiency causes endemic goitre, goitrous hypothyroidism and congenital hypothyroidism (formerly endemic cretinism).

• Graves disease — the commonest cause of hyperthyroidism: a stimulating autoantibody (TSI) against the TSH receptor (most autoantibodies inhibit). Goitre, exophthalmos, infiltrative dermopathy. Toxic nodular goitre (Plummer) can result from TSH-receptor gene mutations.

• Hashimoto thyroiditis: chronic autoimmune thyroiditis, far commoner in women; painless goitre and hypothyroidism; high thyroid peroxidase antibodies; dense lymphocytes with lymphoid follicles and scarring; small rise in thyroid tumours, rarely lymphoma. The usual cause of primary hypothyroidism (low T4/T3, high TSH) where iodine is sufficient.

• Subacute thyroiditis: likely viral; fever, tender thyroid, high ESR; transient hyperthyroidism then hypothyroidism; giant cells with less lymphocytic infiltrate.

Thyroid Carcinoma

• From follicular cells (papillary, follicular, oncocytic, anaplastic) or parafollicular C cells (medullary).

• Papillary: 80–90%; women 3:1; BRAF V600E; spreads by lymphatics to neck nodes (a third), sometimes lung.

• Follicular: about 2%; older patients and iodine-deficient regions; more aggressive because it spreads through the blood (distant metastases).

• Medullary: about 4%; C cells make calcitonin; 25% familial (RET) — MEN 2A and 2B.

• Anaplastic: about 1% but 20% of thyroid cancer deaths; older patients; rapid, painful enlargement.

Diabetes Mellitus

• Type 1: autoimmune destruction of beta cells (autoantibodies help diagnosis). Type 2: insulin resistance with relative deficiency; islets look normal but often contain amyloid (amylin).

• Diagnosis: HbA1c ≥ 6.5%, fasting glucose ≥ 126 mg/dL, 2-hour OGTT ≥ 200 mg/dL, or random glucose ≥ 200 mg/dL with symptoms.

• Complications: microvascular (retinopathy, nephropathy, neuropathy) and macrovascular (atherosclerosis).

Parathyroid, Adrenal and Pancreas

• Primary hyperparathyroidism: a single adenoma in about 85%; women, ages 30–50. Think of MEN when young or multiglandular.

• Addison disease (primary adrenal insufficiency): about 90% autoimmune in the US and Europe; the rest from granulomas (TB, histoplasmosis), tumour, amyloid, haemorrhage. Hypotension and hyperpigmentation with high ACTH.

• Cushing syndrome: moon face, truncal obesity, bruising. ACTH-dependent: Cushing disease (pituitary tumour) or ectopic ACTH (small cell lung carcinoma, neuroendocrine tumours). ACTH-independent: glucocorticoid therapy, adrenal adenoma or carcinoma.

• Phaeochromocytoma: catecholamine-secreting chromaffin tumour; persistent or paroxysmal hypertension; adrenal ones are bilateral in 10% (20% in children) and malignant in about 10%; diagnosed with plasma or urine metanephrines.

• Primary aldosteronism: adrenal hyperplasia, adenoma or carcinoma → hypertension, weakness, hypokalaemia; high aldosterone with low renin.

• Pancreatic cancer: ductal adenocarcinoma, 80% in the head; weight loss, pain, jaundice; risks smoking, chronic pancreatitis, obesity; CA 19-9 is for monitoring, not screening.

Traps the Examiner Sets

• Papillary → lymph nodes; follicular → blood (bone, lung).

• Graves antibody stimulates; most autoantibodies block.

• Painful thyroid + giant cells = subacute; painless + lymphoid follicles = Hashimoto.

• Cushing disease = pituitary; Cushing syndrome = any cause.

• Medullary thyroid carcinoma → think calcitonin, RET, MEN 2.

Memory Hooks & Shortcuts

Shortcuts to lock in this article's numbers and lists. Each one only re-packages facts proven above.

• 🧠 Papillary Pops into nodes; Follicular Flows in blood — thyroid cancer spread

• 🧠 Medullary = Calcitonin + RET → MEN 2 — medullary carcinoma

• 🧠 Graves Gas pedal (stimulates); Hashimoto Hits the brakes (destroys) — thyroid autoimmunity

• 🧠 Subacute is Sore with giant cells — subacute thyroiditis

• 🧠 MEN 1 = 3 P's: Parathyroid, Pancreas, Pituitary — MEN 1

• 🧠 Phaeo = rule of 10s (bilateral, malignant) — phaeochromocytoma

Rapid-Revision Cards

• Graves

  Stimulating TSH-receptor antibody; goitre, exophthalmos, dermopathy.

• Plummer

  Toxic nodular goitre; TSH-receptor mutations.

• Hashimoto

  TPO antibodies; lymphoid follicles; rare lymphoma.

• Subacute thyroiditis

  Viral; tender; giant cells; high ESR.

• Iodine deficiency

  Endemic goitre; congenital hypothyroidism.

• Papillary

  80–90%; BRAF V600E; lymphatic spread.

• Follicular

  ~2%; iodine deficiency; blood spread.

• Medullary

  ~4%; C cells; calcitonin; RET.

• Anaplastic

  ~1%; elderly; painful; 20% of deaths.

• Type 1 DM

  Autoimmune beta-cell loss.

• Type 2 DM

  Insulin resistance; islet amyloid.

• DM cut-offs

  HbA1c ≥ 6.5%; FPG ≥ 126; OGTT ≥ 200.

• Primary HPT

  Adenoma ~85%; women 30–50.

• MEN 1

  Parathyroid ≥ 95%, pancreas NET, pituitary; menin.

• MEN 2A

  MTC, phaeo, HPT; RET.

• MEN 2B

  MTC, phaeo, ganglioneuromas; RET.

• Addison

  ~90% autoimmune (West); TB; pigmentation.

• Cushing disease

  Pituitary ACTH tumour.

• Ectopic ACTH

  Small cell lung cancer, NETs.

• Phaeo

  Chromaffin; 10% bilateral; ~10% malignant; metanephrines.

• Primary aldosteronism

  Hypertension, hypokalaemia; low renin.

• Pancreatic cancer

  Ductal; 80% head; CA 19-9 monitoring.

Sources

Facts in this article were checked against these documents.

• MSD Manual Professional: Hyperthyroidism; Hypothyroidism; Hashimoto Thyroiditis; Subacute Thyroiditis; Simple Nontoxic Goiter; Thyroid Cancers — Merck & Co. (MSD Manuals), reviewed 2025–26 (link)

• MSD Manual Professional: Overview of Diabetes Mellitus; Type 1 Diabetes — Merck & Co. (MSD Manuals), reviewed 2025–26 (link)

• MSD Manual Professional: Hypercalcemia; Addison Disease; Cushing Syndrome; Pheochromocytoma; Primary Aldosteronism — Merck & Co. (MSD Manuals), reviewed 2025–26 (link)

• MSD Manual Professional: Pancreatic Cancer; Multiple Endocrine Neoplasia Syndromes — Merck & Co. (MSD Manuals), reviewed 2025 (link)

• Competency Based Undergraduate Curriculum, Pathology (PA 31) — National Medical Commission, 2024

Test Yourself: Practice Questions

Thirty questions in NEET PG style, most of them clinical vignettes.

Practice Questions (NEET PG pattern)

Original questions written in the style of the exam: +4 for a correct answer, −1 for a wrong one. Every answer was checked against the sources listed above. NEET PG papers are not published by NBEMS, so these are not past-paper questions.

Q1. A woman has hyperthyroidism, a diffuse goitre and protruding eyes. The pathogenesis is

• (a) viral destruction of follicles

• (b) a TSH-secreting pituitary tumour

• (c) an inhibitory antibody against TPO

• (d) a stimulating autoantibody against the TSH receptor

Q2. Which skin finding belongs to Graves disease?

• (a) acanthosis nigricans only

• (b) erythema nodosum

• (c) infiltrative dermopathy

• (d) vitiligo always

Q3. A toxic multinodular goitre (Plummer disease) can arise from

• (a) iodine excess only

• (b) giant cell infiltration

• (c) TSH-receptor gene mutations causing continuous activation

• (d) TPO antibodies

Q4. A middle-aged woman has a painless firm goitre and hypothyroidism; thyroid peroxidase antibodies are very high. Histology would show

• (a) papillae with clear nuclei

• (b) giant cells around damaged follicles

• (c) amyloid stroma

• (d) dense lymphocytic infiltrate with lymphoid follicles and scarring

Q5. A rare but recognised tumour that arises in long-standing Hashimoto thyroiditis is

• (a) thyroid lymphoma

• (b) medullary carcinoma

• (c) parathyroid adenoma

• (d) phaeochromocytoma

Q6. After a viral illness, a woman has fever, a painful tender thyroid, high ESR and transient hyperthyroidism. Histology shows

• (a) lymphoid follicles

• (b) giant cell infiltration with follicular disruption

• (c) papillary fronds

• (d) amyloid

Q7. In iodine-sufficient regions, the commonest cause of primary hypothyroidism is

• (a) Hashimoto (autoimmune) thyroiditis

• (b) thyroid cancer

• (c) pituitary failure

• (d) subacute thyroiditis

Q8. In severely iodine-deficient regions, a major consequence in newborns is

• (a) Graves disease

• (b) medullary carcinoma

• (c) MEN 2

• (d) congenital hypothyroidism (formerly endemic cretinism)

Q9. The commonest thyroid cancer is

• (a) follicular carcinoma

• (b) anaplastic carcinoma

• (c) papillary carcinoma (80–90%)

• (d) medullary carcinoma

Q10. The commonest genetic driver of papillary thyroid carcinoma is

• (a) TP53 only

• (b) RAS only

• (c) RET in all cases

• (d) BRAF V600E

Q11. The thyroid cancer that characteristically spreads through lymphatics to regional neck nodes is

• (a) follicular carcinoma

• (b) papillary carcinoma

• (c) anaplastic carcinoma

• (d) lymphoma only

Q12. An older patient from an iodine-deficient area has a thyroid cancer with distant blood-borne metastases. The likely type is

• (a) medullary carcinoma

• (b) Hashimoto lymphoma

• (c) follicular carcinoma

• (d) papillary carcinoma

Q13. A thyroid cancer from parafollicular cells that secretes calcitonin is

• (a) papillary carcinoma

• (b) oncocytic carcinoma

• (c) follicular carcinoma

• (d) medullary carcinoma

Q14. Familial medullary thyroid carcinoma is caused by mutation of

• (a) VHL

• (b) MEN1 (menin)

• (c) the RET proto-oncogene

• (d) BRAF

Q15. A patient has medullary thyroid carcinoma, phaeochromocytoma and primary hyperparathyroidism. The syndrome is

• (a) MEN 2A

• (b) von Hippel-Lindau

• (c) MEN 2B

• (d) MEN 1

Q16. An elderly patient has a rapidly enlarging, painful thyroid mass; histology shows an undifferentiated tumour. This is

• (a) papillary carcinoma

• (b) anaplastic carcinoma

• (c) subacute thyroiditis

• (d) follicular adenoma

Q17. Type 1 diabetes is primarily due to

• (a) glucagon excess

• (b) insulin resistance

• (c) islet amyloid

• (d) autoimmune destruction of pancreatic beta cells

Q18. Pancreatic islets in type 2 diabetes characteristically contain

• (a) granulomas

• (b) amyloid (amylin) deposits

• (c) haemosiderin

• (d) insulitis with lymphocytes always

Q19. Which value diagnoses diabetes mellitus?

• (a) fasting glucose 110 mg/dL

• (b) HbA1c 5.9%

• (c) 2-hour OGTT 160 mg/dL

• (d) HbA1c 6.7%

Q20. The microvascular complications of diabetes are

• (a) retinopathy, nephropathy and neuropathy

• (b) cataract only

• (c) pancreatitis

• (d) stroke, MI and gangrene

Q21. A woman aged 45 has hypercalcaemia with high PTH. Surgery is most likely to find

• (a) normal glands

• (b) parathyroid carcinoma

• (c) four-gland hyperplasia always

• (d) a single parathyroid adenoma

Q22. In MEN 1, the commonest endocrine abnormality is

• (a) medullary thyroid carcinoma

• (b) hyperparathyroidism (≥ 95%)

• (c) Graves disease

• (d) phaeochromocytoma

Q23. In the US and Europe, the commonest cause of primary adrenal insufficiency is

• (a) tuberculosis

• (b) haemorrhage

• (c) metastases

• (d) autoimmune adrenalitis (~90%)

Q24. A patient with primary adrenal insufficiency has darkening of the skin. The other typical finding is

• (a) hypertension

• (b) hypokalaemia

• (c) hypotension

• (d) weight gain

Q25. Cushing syndrome caused by an ACTH-secreting pituitary tumour is called

• (a) ectopic ACTH syndrome

• (b) Nelson syndrome

• (c) Conn syndrome

• (d) Cushing disease

Q26. A patient with a lung mass develops features of cortisol excess. The likely mechanism is

• (a) ectopic ACTH from small cell carcinoma

• (b) pituitary adenoma

• (c) adrenal adenoma

• (d) exogenous steroids

Q27. A patient has paroxysmal hypertension; plasma free metanephrines are high. The tumour arises from

• (a) parafollicular cells

• (b) chromaffin cells

• (c) zona fasciculata

• (d) zona glomerulosa

Q28. Adrenal phaeochromocytomas are bilateral in about

• (a) 10% (20% in children)

• (b) 50%

• (c) 90%

• (d) never

Q29. A hypertensive patient has episodic weakness and hypokalaemia; aldosterone is high and renin low. The disorder is

• (a) phaeochromocytoma

• (b) Addison disease

• (c) primary aldosteronism

• (d) Cushing disease

Q30. A smoker has weight loss, abdominal pain and jaundice; imaging shows a mass in the pancreatic head. The likely tumour and the marker used to monitor it are

• (a) gastrinoma — gastrin

• (b) acinar cell carcinoma — AFP

• (c) ductal adenocarcinoma — CA 19-9

• (d) insulinoma — insulin

Active Recall

From memory: explain Graves disease and toxic nodular goitre; contrast Hashimoto and subacute thyroiditis; give share, cell, gene and spread of each thyroid carcinoma; state diabetes types, islet changes and diagnostic cut-offs; name the usual lesion of primary hyperparathyroidism; list causes of Addison and Cushing syndromes; give phaeochromocytoma and primary aldosteronism features; and list MEN components.