The pathogenesis of lipedema is not completely understood but is believed to be multifactorial. Microvascular dysfunction and increased angiogenesis resulting from hypoxia secondary to excessive expansion of fatty tissue are also thought to play a role in abnormal tissue development. This microangiopathy in affected tissues is thought to lead to capillary fragility and subsequent leakage of protein and fluid. Abnormal distribution of alpha and beta estrogen receptors has been reported in fatty tissue of affected areas, and estrogen is believed to contribute to disease development. Familial aggregation of lipedema is commonly observed, and heritability of the condition is likely. Possible inheritance patterns include X-linked dominant or autosomal dominant pattern with sex limitation.
Lipedema is staged based on severity:
- Stage 1 – flat skin with enlarged subcutis
- Stage 2 – induration of overlying skin with irregular appearance
- Stage 3 – larger indurations and deforming fat deposits
The course of lipedema is chronic and can be progressive. Many women have stable disease, some have disease that progresses slowly over decades, and others experience a rapid progression. Secondary lymphedema (lipolymphedema) may develop at any time during the disease course and can occur gradually or suddenly.
For more information, see OMIM.
E65 – Localized adiposity
234102003 – Lipedema
- Obesity – Excessive fat accumulation (BMI > 30 kg/m2) due to genetic and behavioral factors. Adipose tissue is distributed predominantly on the trunk and typically responds to diet and exercise.
- Lymphedema – Accumulation of protein-rich fluid in the interstitial space resulting from lymphatic vessel insufficiency. Lymphedema frequently involves the feet and is often asymmetrical.
- Lipodystrophy – A group of rare acquired or inherited disorders characterized by abnormal adipose tissue metabolism. Many lipodystrophy syndromes have a distinct presentation. See, eg, familial partial lipodystrophy.
- Lipohypertrophy – Symmetrical deposition of fat in the buttocks, thighs, and calves with sparing of the feet. This condition is typically not associated with any pain in the affected limbs.
- Bilateral lower extremity edema – Characterized by expansion of the interstitial fluid volume due to heart failure, cirrhosis, nephrotic syndrome, chronic venous disease, medications (eg, calcium channel blockers), bilateral deep vein thrombosis (DVT), pregnancy, or rarely, a pelvic neoplasm.
- Pretibial myxedema – Nonpitting leg edema due to glycosaminoglycans accumulation that is related to thyroid disease.