How should I evaluate and work up a patient presenting with a buffalo hump?

Evaluation and Workup for Buffalo Hump

Screen all patients with buffalo hump for Cushing's syndrome using a 1 mg overnight dexamethasone suppression test, obtain imaging to characterize the tissue composition, and assess for metabolic comorbidities including diabetes, hypertension, and hyperlipidemia, as buffalo hump may represent a visible marker of systemic metabolic disease rather than isolated lipomatosis.

Initial Clinical Assessment

Focus your history and physical examination on identifying:

• Signs of hypercortisolism: Recent substantial weight gain, central obesity, facial plethora, proximal muscle weakness, easy bruising, purple striae, and hypertension 1, 2
• HIV status and antiretroviral therapy: While historically associated with protease inhibitors, buffalo hump occurs in HIV-negative patients and is not exclusive to those on antiretroviral therapy 3, 4
• Metabolic disease burden: Document presence of obesity (BMI), hypertension, diabetes, and hyperlipidemia—these conditions are notably more prevalent in patients with buffalo hump than in the general population 4
• Functional impairment: Assess neck extension mobility and any discomfort from the mass 5, 6

Biochemical Workup

Mandatory Screening for Cushing's Syndrome

All patients require evaluation for autonomous cortisol secretion:

• 1 mg overnight dexamethasone suppression test is the preferred initial screening test 1, 2
  • Administer 1 mg dexamethasone at 11 PM; measure serum cortisol at 8 AM
  • Cortisol >5.0 µg/dL suggests subclinical Cushing's syndrome 2
  • If abnormal, confirm with a second test (e.g., 2-day low-dose dexamethasone suppression test or 24-hour urinary free cortisol) 2
  • Check ACTH and DHEA-S levels to support the diagnosis 2

Critical caveat: Eight HIV-positive patients with buffalo hump showed normal cortisol suppression and no hypercortisolism 3, and the condition can occur without Cushing's syndrome. However, given that buffalo hump is a classic physical finding of Cushing's syndrome, screening remains mandatory to avoid missing this diagnosis 7.

Metabolic Screening

Given the strong association with metabolic disease 4:

• Fasting glucose or HbA1c (66.7% prevalence of diabetes in one cohort)
• Lipid panel (75% prevalence of hyperlipidemia)
• Blood pressure measurement (66.7% prevalence of hypertension)

Consider screening even in patients without known metabolic disease, as buffalo hump may be the presenting sign 4.

Additional Hormonal Testing (If Indicated)

• Aldosterone-to-renin ratio: Only if hypertension and/or hypokalemia present 1, 2
• Plasma metanephrines or 24-hour urinary metanephrines: Only if signs/symptoms of catecholamine excess or if imaging suggests pheochromocytoma 1, 2
• Sex hormone testing: Generally not indicated unless clinical signs of virilization present 2

Imaging Evaluation

MRI is the preferred imaging modality to characterize tissue composition and guide treatment planning 5:

• Distinguishes between four types:
  • Type I: Dorsocervical fat pad (77.6% of cases)
  • Type II: Dorsocervical fat accumulation (11.2%)
  • Type III: Nuchodorsal lipoma (10.2%)
  • Type IV: Mixed type (1%)
• Identifies degree of fibrosis, which impacts surgical approach 5, 8, 6
• Helps differentiate from other masses requiring different management

If adrenal incidentaloma discovered during workup: Follow guideline-directed evaluation with non-contrast CT to measure Hounsfield units and characterize the lesion 1, 2.

Common Pitfalls to Avoid

• Don't assume HIV association: Only 1 of 383 surgical patients in a recent series was HIV-positive 5
• Don't skip Cushing's screening: Even mild hypercortisolism can cause buffalo hump, and the combination with other conditions (e.g., hypogonadism) may amplify clinical manifestations 7
• Don't overlook new metabolic diagnoses: 25% of patients in one series were newly diagnosed with metabolic disease during buffalo hump evaluation 4
• Don't order adrenal imaging reflexively: Only pursue if biochemical screening suggests adrenal pathology

Algorithm Summary

1. History/Physical → Document Cushing's features, HIV status, metabolic comorbidities, functional impairment
2. Biochemical → 1 mg dexamethasone suppression test (all patients) + metabolic panel
3. Imaging → MRI of neck to characterize tissue and guide surgical planning
4. Conditional testing → Aldosterone/renin ratio if hypertensive; metanephrines if concerning features
5. If Cushing's confirmed → Proceed with adrenal imaging and endocrine referral per guidelines 1, 2