There is an extense review about adrenal incidentaloma (AI) for the dec-2020 number, although the paper was from April. It's more than 40 pdf pages, so it'll be reviewed in a few posts. here the first. Original article here.
Key points:
- It affects 2% of populations, 7% in >70 and rare <40.
- 2% are malignant and 10% have hypersecretion.
- Autonomous cortisol secretion and pheochromocytoma must always be excluded. Aldosterone secretion only when hypertension or hypokalemia.
- Unenhanced TC is the inicial test of choice.
- Once malignancy is excluded the patient can be discharged.
- Careful evaluation of clinical impact before recommending surgery should be exercised in case of cortisol hypersecretion.
EPIDEMIOLOGY
- Prevalence varies, 1-7%, raising with age, peaking 50-70.
- It is rare in <30, in these cases it must always be investigated to exclude malignancy or hypersecretion.
- No clear gender predominance.
- Mean size 30 mm, those <10 mm must not be further investigated unless clinical suspition.
- Size >40 mm increases cancer risk.
- No clear lateralization.
ANATOMY
- Adrenal cortex comes from mesoderm (urogenital ridge) and medulla from ectoderm (neural crest).
- SF1 (NR5A1) is a key factor for cortex development. By 3 years of age 3 layers are developed (glomerulosa, fasciculata, reticular)
- Adrenals weigh 4 grams, 5x2x1 cm and are extensively irrigated.
PHYSIOLOGY
- Glomerulosa zone secretes 100-200 mcg/d of aldosterone thanks to CYP11B2 enzyme.
- Fasciculata zone secretes 10-20 mg/d of cortisol due to CYP11B1.
- Regulation and hormonal actions are beyond this review's scope.
- Catecholamines derive from tyroxine (TH) → L-DOPA (AADC) → DA (DBH)→ NA (FNMT) → A. FNMT is only in adrenal medulla, NA is also syntetized in sympathetic ganglia and paraganglia.
- CA metabolism is varied, NA is deaminated bt MAO to 34 DHPG and by COMT to o-metilated metabolite NMN, A through COMT to MN and DA to methoxythyramine. In pheochromocytoma, 90% of CA are metabolized in the tumor by COMT to o-metilated metabolites MN and NMN. Therefore, these molecules are more reliable tumor markers than A or NA.
HYSTOLOGY.
- Tumors from adrenal medulla are positive to S100 and chromogranin.
- Cortical origin tumors express cytokeratin, alpha inhibin, calretinin and SF1.
- Adrenocortical cancers are positiv for melan A but, unlike melanomas, negative for S100.
- Weiss score >3 is helpful to differentiate adrenal adenoma and carcinoma, and Ki67 is also indicative of aggressive behaviour.
- PASS (pheochromocytoma of de adrenal gland scaling score) and GAPP (grading of the adrenal pheochromocytoma and paraganglioma) are scores to label pheochromocytomas al benign or malignant.
