In which lipodystrophy is a buffalo hump seen?

Buffalo Hump in Lipodystrophy Syndromes

Buffalo hump, characterized by fat accumulation in the dorsocervical region, is most prominently seen in HIV-associated lipodystrophy and Cushing syndrome. In the context of lipodystrophy specifically, buffalo hump is a characteristic feature of HIV-associated lipodystrophy, which is an acquired form of lipodystrophy that occurs as a complication of antiretroviral treatment. 1

HIV-Associated Lipodystrophy

HIV-associated lipodystrophy presents with distinctive fat redistribution patterns:

• The condition manifests as fat redistribution with loss of subcutaneous fat, increase in intra-abdominal fat, buffalo hump, or breast hypertrophy 1
• It appears in three prevalent forms:
  • Generalized or localized lipoatrophy (involving extremities, buttocks, and face)
  • Lipohypertrophy with generalized or local fat deposition (involving abdomen, breasts, dorsocervical region [buffalo hump], and supraclavicular area)
  • Mixed pattern with central adiposity and peripheral lipoatrophy 1

Risk Factors and Associations

• Increased duration of HIV infection 1
• High viral load 1
• Low CD4 counts before highly active antiretroviral therapy (HAART) 1
• Antiretroviral treatment, particularly protease inhibitors, though it can occur with other regimens as well 1, 2
• Hyperinsulinemia (higher fasting insulin levels are independently associated with buffalo hump) 3
• Higher body mass index and waist/hip ratio 3

Metabolic Implications

• Buffalo hump in HIV-associated lipodystrophy is not associated with hypercortisolism (unlike in Cushing syndrome) 2
• It is associated with hyperinsulinemia but not necessarily with dyslipidemia 3
• HAART-associated lipodystrophy normalizes resting energy expenditure but has only minor effects on lipolysis 1
• The metabolic changes appear to be permanent, as discontinuation of HAART does not influence the degree of lipodystrophy 1

Other Lipodystrophy Syndromes with Buffalo Hump

Symmetrical Multiple Lipomatosis (Madelung's Disease)

• Occurs preferentially in men who abuse alcohol 4
• Classic subtype affects the upper body and nuchal region with a buffalo hump appearance 4
• Often accompanied by metabolic components including obesity 4

Genetic Lipodystrophy Syndromes

• Familial partial lipodystrophy (particularly Dunnigan variety) may present with fat redistribution, though buffalo hump is not as characteristic as in acquired forms 1
• These disorders involve fat loss from extremities more than trunk 1

Clinical Management

• Medical treatment of lipodystrophy itself is generally not effective 1
• Avoiding antiretroviral drugs with strong metabolic adverse effects may prevent or partially reverse lipodystrophy 1
• Management should focus on:
  • Screening for metabolic complications (insulin resistance, diabetes mellitus) 1, 3
  • Monitoring blood pressure, which is often elevated in patients with buffalo hump 3
  • Assessing for other features of lipodystrophy, as buffalo hump rarely occurs in isolation 3

Diagnostic Approach

When evaluating a patient with buffalo hump, consider:

• HIV status and antiretroviral medication history 1
• Screening for Cushing syndrome (24-hour urinary free cortisol, overnight dexamethasone suppression test) to rule out hypercortisolism 2
• Assessment of insulin levels and glucose tolerance 3
• Evaluation of body composition (dual-energy X-ray absorptiometry) to assess fat distribution patterns 2
• Look for signs of lipodystrophy (loss of subcutaneous fat, triceps skinfold thickness, waist/hip ratio) 1

Buffalo hump in the context of HIV infection should prompt consideration of lipodystrophy syndrome and its metabolic implications, particularly insulin resistance and cardiovascular risk factors.