Cushing’s syndrome

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"Cushing syndrome"[MeSH Terms] AND diagnosis

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python3 -c " import pdfplumber path = '/home/daytona/workspace/attachments/213e9c31-4ee1-4ac8-93ed-ebf3a21a0277/Part 24 -The Endocrine System - Nelson 2024 (1).pdf' with pdfplumber.open(path) as pdf: print(f'Total pages: {len(pdf.pages)}') # Search for Cushing's syndrome pages for i, page in enumerate(pdf.pages): text = page.extract_text() or '' if 'Cushing' in text: print(f'Page {i+1}: Cushing found') "

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Cushing syndrome clinical features moon face buffalo hump

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python3 << 'EOF' import pdfplumber, re path = '/home/daytona/workspace/attachments/213e9c31-4ee1-4ac8-93ed-ebf3a21a0277/Part 24 -The Endocrine System - Nelson 2024 (1).pdf' with pdfplumber.open(path) as pdf: print(f'Total pages: {len(pdf.pages)}') for i, page in enumerate(pdf.pages[:10]): text = page.extract_text() or '' if text.strip(): print(f'\n=== PAGE {i+1} ===') print(text[:300]) EOF

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python3 << 'EOF' import pdfplumber path = '/home/daytona/workspace/attachments/213e9c31-4ee1-4ac8-93ed-ebf3a21a0277/Part 24 -The Endocrine System - Nelson 2024 (1).pdf' with pdfplumber.open(path) as pdf: print(f'Total pages: {len(pdf.pages)}') for i, page in enumerate(pdf.pages): text = page.extract_text() or '' if 'Cushing' in text: print(f'Page {i+1}: snippet -> {text[:100]}') EOF

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python3 << 'EOF' import subprocess, sys path = '/home/daytona/workspace/attachments/213e9c31-4ee1-4ac8-93ed-ebf3a21a0277/Part 24 -The Endocrine System - Nelson 2024 (1).pdf' result = subprocess.run(['pdftotext', '-layout', path, '-'], capture_output=True, text=True, timeout=60) text = result.stdout # find Cushing pages idx = text.find('Cushing') if idx >= 0: print(f'Found at index {idx}') print(text[max(0,idx-200):idx+2000]) else: print('Not found') print(text[:500]) EOF

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python3 << 'EOF' import subprocess path = '/home/daytona/workspace/attachments/213e9c31-4ee1-4ac8-93ed-ebf3a21a0277/Part 24 -The Endocrine System - Nelson 2024 (1).pdf' result = subprocess.run(['pdftotext', '-layout', path, '-'], capture_output=True, text=True, timeout=60) text = result.stdout # Find the dedicated Cushing section import re positions = [m.start() for m in re.finditer(r'Cushing', text)] print(f'Found {len(positions)} occurrences of Cushing') for pos in positions[:10]: snippet = text[max(0,pos-50):pos+100].replace('\n', ' ') print(f' pos {pos}: ...{snippet}...') EOF

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python3 << 'EOF' import subprocess, re path = '/home/daytona/workspace/attachments/213e9c31-4ee1-4ac8-93ed-ebf3a21a0277/Part 24 -The Endocrine System - Nelson 2024 (1).pdf' result = subprocess.run(['pdftotext', '-layout', path, '-'], capture_output=True, text=True, timeout=60) text = result.stdout # Find the adrenal/Cushing section with more detail # Look for "Cushing Syndrome" as a chapter heading matches = [(m.start(), m.group()) for m in re.finditer(r'Cushing Syndrome|Cushing syndrome|CUSHING SYNDROME|Hypercortisolism', text)] for pos, match in matches: snippet = text[max(0,pos-100):pos+200].replace('\n',' ') print(f'pos {pos} ({match}): {snippet[:250]}') print() EOF

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Now I have all the material needed. Here is the comprehensive overview:

Cushing Syndrome

Based on Nelson Textbook of Pediatrics 2024 (Chapter 619) and Campbell-Walsh Urology

Definition

Cushing syndrome is the clinical state resulting from abnormally high blood levels of cortisol or other glucocorticoids, whether from exogenous administration or endogenous oversecretion. — Nelson 2024, Ch. 619

Etiology & Classification

Causes are divided into three main groups:

1. Exogenous (Iatrogenic) — Most Common Overall

The most frequent cause in the Western world. Synthetic glucocorticoids given orally, topically, or by inhalation can produce the syndrome, even at low doses. A careful history should inquire about herbal remedies, nasal sprays, and surreptitious use.

2. ACTH-Dependent (80–85% of endogenous cases)

Cause	Key Facts
Cushing disease (pituitary corticotroph adenoma)	~70% of endogenous CS; almost always a microadenoma <5 mm; ♀ > ♂ overall, but prepubertal males > females
Ectopic ACTH secretion	~10% of endogenous CS; in children: associated with islet cell carcinoma of the pancreas, neuroblastoma, ganglioneuroblastoma, hemangiopericytoma, Wilms tumor, thymic carcinoid; causes the highest cortisol and most severe hypokalemia
Ectopic CRH secretion	Extremely rare

3. ACTH-Independent (~15–20% of endogenous cases)

Cause	Key Facts
Adrenal adenoma	Most common adrenal cause in children >7 yr
Adrenocortical carcinoma	~8% of CS; poor prognosis; virilization often co-exists
PPNAD (Primary Pigmented Nodular Adrenocortical Disease)	<1%; normal-sized glands with black/brown nodules; associated with Carney complex (PRKAR1A gene, chr 17q22–24); classic paradoxical rise on high-dose dexamethasone suppression test
BMAH (Bilateral Macronodular Adrenal Hyperplasia)	<1%; ARMC5 tumor-suppressor gene abnormal in ~40%
McCune-Albright syndrome	GNAS (Gsα) somatic activating variant

Pediatric note: In children under 5 years, adrenal causes (carcinoma, McCune-Albright) predominate over pituitary causes.

Pathophysiology

The hypothalamic-pituitary-adrenal (HPA) axis normally maintains cortisol within a circadian rhythm: peak at 8 AM, nadir at ~11 PM. CRH → ACTH → cortisol → negative feedback at hypothalamus and pituitary. In Cushing syndrome, this feedback loop is disrupted and the normal circadian rhythm is lost.

The adrenal cortex's zona fasciculata produces up to 20 mg cortisol/day under ACTH drive. Cortisol exerts effects on virtually every organ system (see figure below).

Clinical Manifestations

The most sensitive indicator of excess glucocorticoid secretion in children is growth failure, which generally precedes other signs. (Children with simple obesity are usually tall, whereas those with Cushing syndrome are short or have a decelerating growth rate.)

Classic features of Cushing syndrome — moon facies, dorsocervical fat pad (buffalo hump), and wide violaceous striae on trunk and thighs in a 26-year-old female with left adrenal adenoma

Table: Presenting Signs and Symptoms (Nelson 2024, Table 619.2)

System	Features
Dermatologic	Moon facies (rounded, flushed), facial plethora, acne, easy bruising, supratemporal and supraclavicular fat pads, hirsutism, fine downy hair, violaceous striae (unusual in children <7 yr), fungal infections, acanthosis nigricans
Growth	Growth deceleration + weight gain; central obesity; "buffalo hump" (nonspecific)
Cardiovascular	Hypertension, coagulopathy
Metabolic	Hyperglycemia → frank diabetes, dyslipidemia, insulin resistance
Gonadal	Amenorrhea, virilization (clitoromegaly, pubic hair, deepened voice), gynecomastia; pubertal arrest or delay
Musculoskeletal	Osteoporosis, pathologic fractures, proximal muscle weakness
Neuropsychiatric	Depression, anxiety, mood swings, irritability, fatigue, headache
Other	Nephrolithiasis, increased susceptibility to infection

In infants, generalized obesity is common and findings are more dramatic. In older children, truncal/facial obesity with relative limb sparing is typical.

Laboratory Findings & Diagnosis

Screening Tests (require ≥2 abnormal results to confirm)

Test	Details
Late-night salivary cortisol	Circadian rhythm is lost in CS; midnight cortisol >4.4 μg/dL strongly suggests the diagnosis. Can be collected at home.
24-hour urinary free cortisol (UFC)	Expressed per gram creatinine (corrects for body size and collection completeness). Elevated in CS.
Overnight dexamethasone suppression test (DST)	25–30 μg/kg (max 2 mg) at 11 PM → 8 AM cortisol <5 μg/dL is normal. Failure to suppress = abnormal. Measure dexamethasone level to confirm adequate dosing.

Distinguishing the Cause

Once CS is confirmed:

Measure plasma ACTH (two samples)
- ACTH <10 pg/mL → ACTH-independent → CT/MRI of adrenals
- ACTH >20 pg/mL → ACTH-dependent → pituitary MRI + further testing
- ACTH 10–20 pg/mL (indeterminate) → CRH stimulation test
High-dose dexamethasone suppression test (HDDSST): 30 μg/kg/24 hr × 2 days then 120 μg/kg/24 hr × 2 days. Suppression of cortisol with the larger dose (not smaller) = pituitary Cushing disease. ACTH-independent disease shows no suppression.
CRH stimulation: Patients with ACTH-dependent CS show an exaggerated ACTH and cortisol response; adrenal tumor patients show no response.
Bilateral Inferior Petrosal Sinus Sampling (BIPSS) after CRH stimulation: the gold standard to distinguish Cushing disease from ectopic ACTH. High petrosal:peripheral ACTH ratio confirms pituitary origin.
Imaging:
- CT detects virtually all adrenal tumors >1.5 cm
- Pituitary MRI (with gadolinium) for adenomas — but 50% of Cushing disease patients have no visible abnormality on MRI; and 10% of the general population have incidental pituitary findings

Algorithm summary (Fig. 619.2, Nelson 2024):

Confirmed CS → ACTH measurement
├── <10 pg/mL (ACTH-independent) → CT/MRI adrenals
│   └── Unilateral mass → adenoma/carcinoma
│   └── Bilateral → macronodular or micronodular hyperplasia
│
└── >20 pg/mL (ACTH-dependent) → Pituitary MRI + HDDSST + CRH test
    ├── Adenoma >6 mm + concordant tests → Surgery (Cushing disease confirmed)
    ├── Adenoma <6 mm or discordant tests → BIPSS
    └── Negative pituitary imaging → CT/MRI neck/chest/abdomen/pelvis + octreoscan/PET → ectopic ACTH tumor

Differential Diagnosis

Simple obesity: children are tall, cortisol suppresses normally with dexamethasone, nighttime salivary cortisol is normal
Pseudo-Cushing states (may show false-positive cortisol tests): major depression, alcoholism, morbid obesity, poorly controlled diabetes
Glucocorticoid resistance (Chrousos syndrome): elevated cortisol + ACTH without typical CS phenotype; presents with hypertension, hypokalemia, precocious pseudopuberty
Exogenous steroid use (always exclude first with careful history)

Treatment

Cushing Disease (Pituitary)

Transsphenoidal pituitary microsurgery is the treatment of choice in children
- Overall success rate: 60–98% (initial remission); long-term success 50–98%
- Low postoperative cortisol predicts long-term remission
- Relapse: reoperation or pituitary radiotherapy
Pasireotide (somatostatin analog): approved for adults with persistent/recurrent disease post-surgery or surgical contraindication — inhibits ACTH secretion
Cyproheptadine (serotonin antagonist): rarely used in children; remissions not sustained

Adrenal Causes

Surgical resection (laparoscopic adrenalectomy where possible)
For bilateral adrenalectomy: requires lifelong adrenal replacement therapy; risk of Nelson syndrome (~25% of adults post-bilateral adrenalectomy) — Nelson syndrome = markedly elevated ACTH with skin hyperpigmentation from unresected pituitary adenoma

Adrenal Steroidogenesis Inhibitors (preoperative or adjunct)

Drug	Mechanism
Mitotane	Cytotoxic to adrenocortical cells; FDA-approved
Osilodrostat	Cortisol synthesis inhibitor; FDA-approved
Metyrapone	11β-hydroxylase inhibitor
Ketoconazole / Levoketoconazole	Inhibits multiple steroidogenic enzymes; levoketoconazole in advanced development
Aminoglutethimide	Blocks cholesterol side-chain cleavage
Etomidate (IV)	For acute severe hypercortisolism
Mifepristone	Glucocorticoid receptor antagonist; used in limited cases

Postoperative Management

Replace cortisol 10 mg/m²/24 hr in three divided doses after immediate postoperative period — until HPA axis recovers (may take up to 30 months)
Monitor for sepsis, pancreatitis, thrombosis, poor wound healing
Expect catch-up growth and pubertal progress, but bone density remains abnormal and adult height is often compromised
Check for GH deficiency post-treatment and treat if present

Genetics Summary (Fig. 619.1, Nelson 2024)

Cause	Key Genes
Cushing disease	USP8, MEN1, CDKIs, CDKN1B/p27, AIP, DICER1
PPNAD / Carney complex	PRKAR1A (chr 17q22–24), PDE11A, PDE8B, PRKACA
BMAH	ARMC5, MEN1, GNAS1, PDE11A, PDE8B
Adrenal adenoma	PRKACA (somatic activating variant), CTNNB1
McCune-Albright	GNAS (somatic Gsα activating variant)
Ectopic ACTH	RET, MEN1

Recent Evidence (PubMed 2024–2025)

A 2024 systematic review and meta-analysis (PMID 38888685) addressed the challenge of differentiating true Cushing syndrome from non-neoplastic hypercortisolism (pseudo-Cushing), highlighting the diagnostic conundrum in clinical practice.
A 2025 meta-analysis on ectopic Cushing syndrome (PMID 40455890) characterized survival probabilities — ectopic CS carries a significantly worse prognosis than pituitary or adrenal forms.
A 2024 meta-analysis (PMID 38840128) documented a spectrum of thyroid dysfunction in CS, including suppressed TSH and altered thyroid hormone metabolism.

Sources: Nelson Textbook of Pediatrics 2024, Ch. 619 (attached PDF) | Campbell-Walsh-Wein Urology, Ch. 106

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