• Fluid
  
• Overgrowth
• Tumour
• Shrinkage of t'other side

Fluid flow

• Net pressure is OUT OF capillaries over their entire length
• => There is no venous reabsorption of fluid
• => Lymphatics do it all
• NB this is not what used to be taught

Lymphatic failure

• Filtration oedema
• Lymphatics still functional, just overloaded
• e.g. In acute heart failure
• Pits easily as fluid is still flowing fine
• Lymphoedema
• Damage to lymphatics
• e.g. From sustained filtration oedema
• Pits at early stages
• Non-pitting later on
  

Lymphoedema stages

• Stage 0 (latent):
• Vessel damage but transport capacity is still sufficient for the amount of lymph being removed
• Lymphedema not present
• Stage 1 (spontaneously reversible)
• Tissue is still at the "nonpitting" stage
• Usually upon waking in the morning, the limb or affected area is normal or almost normal in size
• Stage 2 (spontaneously irreversible)
• The tissue now has a spongy consistency and is considered "pitting"
• Fibrosis found in stage 2 lymphedema marks the beginning of the hardening of the limbs and increasing size
• Stage 3 (lymphostatic elephantiasis)
• Swelling is irreversible and usually the limb(s) or affected area is very large
• The tissue is hard (fibrotic) and unresponsive

Milroy's disease

• VEGFR-3 mutation => Spontaneous oedema

Distinguishing features of lymphoedema (vs filtration oedema)

• Only slightly helped by elevation
• Diuretics don't help
• >1 attack of cellulitis
• Due to reduced immune cell trafficking
• Exercise helps
• Pitting
• Skin thickening/hyperkeratosis
  

Notes

• Lymphatics
• Small collecting ducts
• Large draining ducts, with valves + smooth muscle
• Don't confuse lipodermatosclerosis with cellulitis
• Requires elevation and compression, not antibiotics
• CCBs block lymphatic smooth muscle pumping and can cause lymphoedema
• Plexiform neurofibroma
• Brown spots + swollen leg