Practice 14 structured short- and long-answer medical questions on ADRENAL NEOPLASMS — Adenoma vs Carcinoma. Review model answers for exam revision.
Answer: Model answer pending
Answer: Model answer pending
Answer: Model answer pending
Answer: Model answer pending
Answer: **Morphology:** - **Diffuse glomerulosclerosis** — uniform mesangial matrix expansion — most common finding - **Nodular glomerulosclerosis (Kimmelstiel-Wilson nodules)** — ovoid/spherical nodules of acellular matrix in periphery of glomerulus — **pathognomonic of diabetic nephropathy** - GBM thickening - Hyaline arteriolosclerosis — affects both afferent AND efferent arterioles (efferent involvement is unique to DM) - Exudative lesions — hyaline caps, capsular drops **Clinical progression:** - Stage 1: Hyperfiltration — ↑ GFR, no proteinuria - Stage 2: Silent — GBM thickening, microstructural changes - Stage 3: Microalbuminuria (30–300 mg/day) — earliest clinical sign - Stage 4: Macroalbuminuria (>300 mg/day) + ↓ GFR + hypertension - Stage 5: ESRD — dialysis or transplant **Key points:** - Microalbuminuria = earliest detectable sign of diabetic nephropathy - ACEi/ARBs — slow progression by reducing intraglomerular pressure (dilate efferent arteriole) - Both afferent and efferent arteriolar hyalinosis — unique to DM, distinguishes from hypertensive nephropathy (afferent only) ## Practice Questions
Answer: Model answer pending
Answer: Model answer pending
Answer: Model answer pending
Answer: Model answer pending
Answer: Model answer pending
Answer: Model answer pending
Answer: Model answer pending
Answer: Model answer pending
Answer: This content differentiates between adrenal adenomas and carcinomas based on their size, gross appearance, histological features, capsular integrity, metastatic potential, and genetic markers. It highlights key diagnostic criteria for malignancy and discusses the prognostic implications of each condition. A separate section covers Multiple Endocrine Neoplasia (MEN) syndromes, detailing the genetic basis, characteristic endocrine gland involvement, and other associated features of MEN1, MEN2A, and MEN2B. Mnemonics are provided for remembering the glandular involvement in MEN syndromes, along with crucial points for screening and management. The document also briefly touches upon parathyroid cell types, distinguishing between chief cells and oxyphil cells based on their size, cytoplasm, function, and granule content. Finally, it delves into Renal Tubular Acidosis (RTA), defining the condition and comparing the different types (Type 1, 2, and 4) based on their defects, urine pH, serum electrolytes, causes, complications, and treatments. ## Key Points - **Adrenal Carcinoma Diagnosis**: Confirmed by vascular invasion, capsular invasion, or metastasis; cytology alone is insufficient. - **MEN1 Mnemonic**: 3 Ps - Parathyroid, Pancreas, Pituitary. - **MEN2A Mnemonic**: 2 Ps - Parathyroid, Phaeochromocytoma, Medullary thyroid carcinoma. - **MEN2B Features**: Phaeochromocytoma, Medullary thyroid carcinoma, Marfanoid habitus, mucosal neuromas; *no parathyroid involvement*. - **RET Mutation Management**: Screening family members and prophylactic thyroidectomy in carriers. - **Chief Cells**: Predominant functional cells in the parathyroid gland, responsible for PTH synthesis and secretion. - **Oxyphil Cells**: Larger parathyroid cells with abundant mitochondria, unknown function, increase with age. - **RTA Type 4 Hyperkalaemia**: The only type of RTA characterized by hyperkalaemia; others present with hypokalaemia. - **Diabetic Nephropathy Pathogenesis**: Involves hyperglycaemia-induced AGE formation, hyperfiltration, mesangial expansion, and GBM thickening. - **Kimmelstiel-Wilson Nodules**: Pathognomonic histological finding in nodular glomerulosclerosis of diabetic nephropathy. - **Diabetic Nephropathy Arteriolar Hyalinosis**: Affects both afferent and efferent arterioles, distinguishing it from hypertensive nephropathy. - **Microalbuminuria**: The earliest clinical sign of diabetic nephropathy. - **ACEi/ARBs in Diabetic Nephropathy**: Slow progression by reducing intraglomerular pressure. ## Detailed Notes ### ADRENAL NEOPLASMS — Adenoma vs Carcinoma | Feature | Adenoma | Carcinoma | |---|---|---| | Size | Small, <50g | Large, often >100g | | Gross | Yellow, well-circumscribed, smooth | Grey-white, irregular, necrotic | | Histology | Uniform clear cells, thin capsule, no invasion | Pleomorphic cells, mitoses, necrosis, vascular invasion | | Capsule | Intact | Breached — invasion is diagnostic | | Metastasis | No | Yes — only reliable criterion of malignancy alongside invasion | | CDC73/parafibromin | Intact | Mutated in ~70% | | ACTH | Suppressed (autonomous cortisol) | Suppressed | | Prognosis | Excellent after adrenalectomy | Poor — local recurrence in 1/3, distant metastasis in 1/3 | **Key point:** Cytology alone cannot diagnose carcinoma. Only **vascular invasion, capsular invasion, or metastasis** confirms malignancy. ### MEN SYNDROMES (Multiple Endocrine Neoplasia) | Feature | MEN1 | MEN2A | MEN2B | |---|---|---|---| | Gene | MEN1 (chromosome 11q13, tumour suppressor) | RET proto-oncogene | RET proto-oncogene | | Parathyroid | Hyperplasia/adenoma | Hyperplasia | No | | Pancreas | Islet cell tumours (gastrinoma, insulinoma) | No | No | | Pituitary | Adenoma (prolactinoma most common) | No | No | | Adrenal | No | Phaeochromocytoma | Phaeochromocytoma | | Thyroid | No | Medullary thyroid carcinoma | Medullary thyroid carcinoma | | Other | — | — | Marfanoid habitus, mucosal neuromas | **Mnemonic:** - **MEN1 = 3 Ps** — Parathyroid + Pancreas + Pituitary - **MEN2A = 2 Ps** — Parathyroid + Phaeochromocytoma + medullary thyroid - **MEN2B = Phaeochromocytoma + medullary thyroid + marfanoid/neuromas (no parathyroid)** **Key points:** - MEN1 mutation found in 30–35% of sporadic parathyroid adenomas - RET mutation in MEN2 → screen family members → prophylactic thyroidectomy in carriers - Always screen phaeochromocytoma patients for MEN2 ### PARATHYROID CELL TYPES | Cell Type | Size | Cytoplasm | Function | Granules | |---|---|---|---|---| | **Chief cells** | 12–20 μm, predominant | Light to dark pink, polygonal | PTH synthesis and secretion | PTH secretory granules present | | **Oxyphil cells** | Larger than chief cells | Deeply eosinophilic, packed with mitochondria | Unknown (transitional/inactive) | Sparse/absent secretory granules | **Key points:** - Chief cells predominate — they are the functional cells - Oxyphil cells increase with age — appear after puberty - Stromal fat increases up to age 25 → plateaus at ~30% of gland - Adenomas mostly composed of chief cells — oxyphil adenomas rare - Water-clear cell hyperplasia — glycogen-rich clear cells, seen in some hyperplasia ### RENAL TUBULAR ACIDOSIS (RTA) **Definition:** Defect in renal acid-base handling → normal anion gap metabolic acidosis despite normal or near-normal GFR. | Feature | Type 1 (Distal) | Type 2 (Proximal) | Type 4 | |---|---|---|---| | Defect | Impaired H⁺ excretion in collecting duct | Impaired HCO₃⁻ reabsorption in proximal tubule | Hypoaldosteronism → impaired H⁺ and K⁺ excretion | | Urine pH | Always >5.5 (cannot acidify) | <5.5 (can acidify when plasma HCO₃⁻ low) | >5.5 | | Serum K⁺ | ↓ Hypokalaemia | ↓ Hypokalaemia | ↑ **Hyperkalaemia** | | Serum HCO₃⁻ | Very low | Moderately low | Mildly low | | Causes | Sjögren's, SLE, amphotericin B, medullary sponge kidney | Fanconi syndrome, multiple myeloma, Wilson's disease | Diabetic nephropathy, ACEi/ARBs, Addison's disease | | Complications | Nephrocalcinosis, nephrolithiasis, osteomalacia | Rickets/osteomalacia | Arrhythmias from hyperkalaemia | | Treatment | Oral bicarbonate (small doses) | Large oral bicarbonate + treat cause | Fludrocortisone, dietary K⁺ restriction | **Key distinguishing point:** Type 4 is the only RTA with **hyperkalaemia** — all others have hypokalaemia. Type 4 is the most common RTA in clinical practice (diabetic nephropathy). ### DIABETIC NEPHROPATHY — Pathogenesis & Morphology **Pathogenesis (stepwise):**