CLT Pathophysiology of Lymphedema 1 — Questions and Answers
Question 1: Which stage of lymphedema according to the International Society of Lymphology (ISL) is characterized by pitting edema that resolves completely with limb elevation?
- Stage 0 (Latency)
- Stage I (Correct answer)
- Stage II
- Stage III
Correct answer: Stage I
ISL Stage I lymphedema presents with pitting edema that subsides with limb elevation, indicating reversible protein-rich swelling without significant fibrosis.
Question 2: What is the primary pathophysiological mechanism that distinguishes lymphedema from other forms of edema?
- Increased capillary hydrostatic pressure
- Accumulation of protein-rich fluid due to impaired lymphatic transport (Correct answer)
- Decreased plasma oncotic pressure from hypoalbuminemia
- Increased capillary permeability from inflammation
Correct answer: Accumulation of protein-rich fluid due to impaired lymphatic transport
Lymphedema specifically results from the accumulation of protein-rich interstitial fluid when lymphatic transport capacity is overwhelmed or structurally impaired.
Question 3: Which of the following is the most common cause of secondary lymphedema worldwide?
- Breast cancer treatment
- Filariasis (parasitic infection) (Correct answer)
- Trauma and surgery
- Chronic venous insufficiency
Correct answer: Filariasis (parasitic infection)
Filariasis caused by Wuchereria bancrofti is the leading cause of secondary lymphedema globally, affecting hundreds of millions of people in tropical regions.
Question 4: In the Starling equilibrium, which forces favor fluid movement OUT of the capillary into the interstitium?
- Plasma oncotic pressure and interstitial hydrostatic pressure
- Capillary hydrostatic pressure and interstitial oncotic pressure (Correct answer)
- Plasma oncotic pressure and capillary hydrostatic pressure
- Interstitial hydrostatic pressure and interstitial oncotic pressure
Correct answer: Capillary hydrostatic pressure and interstitial oncotic pressure
Capillary hydrostatic pressure pushes fluid out of capillaries, while interstitial oncotic pressure draws fluid into the interstitium; both forces favor filtration into the tissue.
Question 5: What is the primary protein responsible for generating oncotic pressure within the plasma, and what happens to interstitial protein concentration in chronic lymphedema?
- Fibrinogen; decreases over time
- Albumin; increases due to impaired lymphatic clearance (Correct answer)
- Globulin; remains stable throughout disease progression
- Fibronectin; decreases as fibrosis develops
Correct answer: Albumin; increases due to impaired lymphatic clearance
Albumin is the primary plasma protein creating oncotic pressure, and in chronic lymphedema it accumulates in the interstitium because lymphatics cannot remove it, worsening the edema cycle.
Question 6: Which pathological change is characteristic of ISL Stage III lymphedema (lymphostatic elephantiasis)?
- Reversible pitting edema with elevation
- Tissue fibrosis, acanthosis, and skin changes with non-pitting edema (Correct answer)
- Subclinical impairment with normal limb volume
- Moderate pitting edema that does not resolve with elevation
Correct answer: Tissue fibrosis, acanthosis, and skin changes with non-pitting edema
Stage III (elephantiasis) is characterized by irreversible fibrosis, skin thickening (acanthosis), papillomatosis, and non-pitting edema due to chronic protein accumulation and fibrotic tissue remodeling.
Question 7: The 'safety valve' function of the lymphatic system refers to its capacity to do which of the following?
- Prevent blood pressure from rising during exercise
- Increase transport capacity up to 10 times normal to handle excess interstitial fluid (Correct answer)
- Regulate sodium balance in the interstitial compartment
- Filter bacteria before they enter the bloodstream
Correct answer: Increase transport capacity up to 10 times normal to handle excess interstitial fluid
The lymphatic safety valve function describes the system's ability to increase transport capacity up to tenfold above baseline, compensating for increased fluid loads before edema becomes clinically apparent.
CLT Pathophysiology of Lymphedema 1
Which stage of lymphedema according to the International Society of Lymphology (ISL) is characterized by pitting edema that resolves completely with limb elevation?