I have a dorsocervical fat pad and other Cushingoid features but normal cortisol levels; what other conditions could explain these findings?

Dorsocervical Fat Pad with Normal Cortisol: Alternative Diagnoses

When you have a dorsocervical fat pad ("buffalo hump") and other Cushingoid features but normal cortisol testing, you should first consider exogenous glucocorticoid exposure (the most common cause of Cushing syndrome), then pursue repeat testing for cyclic Cushing syndrome, and finally evaluate for pseudo-Cushing states and metabolic syndrome. 1, 2

Immediate Considerations

Exogenous Glucocorticoid Exposure

• The most frequent cause of Cushing syndrome is iatrogenic from exogenous corticosteroids, not endogenous disease. 1
• Review all medications including:
  • Oral, inhaled, topical, or injected corticosteroids 2
  • Joint injections, skin creams, or nasal sprays containing steroids 1
  • Herbal supplements or over-the-counter products that may contain undisclosed steroids 2

Cyclic or Intermittent Cushing Syndrome

• Some patients produce excess cortisol in a cyclic or intermittent pattern, with normal hypothalamic-pituitary-adrenal axis function between cycles. 3
• Single-point cortisol testing may miss the diagnosis entirely if sampled during a quiescent phase 3
• Three of 39 patients with proven Cushing syndrome had normal late-night salivary cortisol on initial testing, with one having documented intermittent hypercortisolism. 4
• Repeat screening tests multiple times over weeks to months, particularly when symptoms worsen 3
• Consider serial late-night salivary cortisol measurements at home to capture fluctuations 4, 5

Diagnostic Algorithm for Persistent Suspicion

Repeat Biochemical Testing

• Use one or more first-line tests: 24-hour urinary free cortisol, late-night salivary cortisol (measured at 11 PM), or 1-mg overnight dexamethasone suppression test. 1, 2
• The combination of elevated late-night salivary cortisol and/or elevated urinary free cortisol identified 100% of patients with proven Cushing syndrome 4
• Normal suppression on dexamethasone test is cortisol <1.8 μg/dL the morning after taking 1 mg at bedtime 1
• Perform testing during periods when symptoms are most prominent, not during asymptomatic intervals. 3

Key Discriminating Features to Assess

Look specifically for features that distinguish true Cushing syndrome from simple metabolic syndrome:

• Wide purple striae (≥1 cm) on abdomen, thighs, or arms - this is highly specific for pathologic hypercortisolism 6, 7
• Proximal muscle weakness - difficulty rising from a chair without using arms or lifting objects overhead 6, 7
• Rapid weight gain over months rather than years with central distribution 6
• Easy bruising and thin, fragile skin 7, 2
• Facial plethora (reddish-purple facial appearance) 7

Alternative Diagnoses to Consider

Metabolic Syndrome

• Hypertension and glucose abnormalities exceed 80% prevalence in both Cushing syndrome and metabolic syndrome, creating diagnostic overlap 6
• Central obesity, dorsocervical fat pad, and supraclavicular fat can occur in severe metabolic syndrome without hypercortisolism 6, 7
• However, the absence of wide purple striae, proximal weakness, and easy bruising argues against Cushing syndrome. 6

Pseudo-Cushing States

• Conditions that can mimic Cushing syndrome include:
  • Severe depression or anxiety disorders 6
  • Chronic alcoholism 2
  • Poorly controlled diabetes 2
  • Severe obesity 2
• These conditions may cause mild cortisol elevation but typically lack the severe multisystem features of true Cushing syndrome 2, 8

Polycystic Ovary Syndrome (PCOS)

• Can present with hirsutism, menstrual irregularities, central obesity, and acne 7
• Does not cause dorsocervical fat pad, proximal weakness, or wide striae 7

Critical Pitfalls to Avoid

• Do not dismiss the diagnosis after a single normal cortisol test if clinical suspicion remains high - cyclic Cushing syndrome requires repeated testing 3
• The average diagnostic delay in Cushing syndrome is 3 years from initial symptoms to diagnosis, resulting in increased cardiovascular mortality. 6
• Dexamethasone suppression testing may produce paradoxical responses in cyclic Cushing syndrome 3
• The prevalence of endogenous Cushing syndrome is low (2-8 per million annually), but delayed diagnosis causes severe multisystem morbidity including cardiovascular disease, infections, and neuropsychiatric disorders. 2, 8

When to Pursue Endocrinology Referral

Refer to endocrinology if:

• Multiple screening tests yield equivocal results 2
• Clinical features strongly suggest Cushing syndrome despite normal initial testing 6
• You suspect cyclic or intermittent hypercortisolism requiring specialized evaluation 3
• Patient has rapid progression of symptoms or severe hypertension (>170/108 mmHg) with Cushingoid features 6