CLT Pathophysiology of Lymphedema 2 — Questions and Answers
Question 1: Primary lymphedema that is present at birth or develops within the first two years of life is classified as:
- Lymphedema praecox
- Lymphedema tarda
- Congenital lymphedema (Milroy disease) (Correct answer)
- Familial lymphedema
Correct answer: Congenital lymphedema (Milroy disease)
Congenital lymphedema, associated with Milroy disease, is present at birth or manifests within the first two years of life due to genetic defects in lymphatic development.
Question 2: Lymphedema praecox, the most common form of primary lymphedema, typically presents at what age range?
- Birth to 2 years
- 2 to 10 years
- Puberty to age 35 (Correct answer)
- After age 35
Correct answer: Puberty to age 35
Lymphedema praecox most commonly appears during puberty through age 35, often triggered by hormonal changes, and predominantly affects females.
Question 3: Which genetic mutation is most commonly associated with Milroy disease (congenital primary lymphedema)?
- FOXC2 gene mutation
- FLT4 gene mutation encoding VEGFR-3 (Correct answer)
- GJC2 gene mutation
- PROX1 gene mutation
Correct answer: FLT4 gene mutation encoding VEGFR-3
Milroy disease is caused by loss-of-function mutations in FLT4, the gene encoding vascular endothelial growth factor receptor-3 (VEGFR-3), which is essential for lymphatic vessel development.
Question 4: How does the lymphatic transport capacity relate to lymphatic load in the development of lymphedema?
- Lymphedema occurs when lymphatic load exceeds transport capacity (Correct answer)
- Lymphedema occurs when transport capacity exceeds lymphatic load
- Lymphatic load and transport capacity are unrelated to edema formation
- Lymphedema only develops when both load and capacity are simultaneously reduced
Correct answer: Lymphedema occurs when lymphatic load exceeds transport capacity
Lymphedema develops when the lymphatic load (volume of fluid and protein entering the interstitium) exceeds the transport capacity of the lymphatic system, leading to fluid accumulation.
Question 5: How does lipedema differ pathophysiologically from lymphedema?
- Lipedema involves abnormal fat deposition symmetrically in extremities and is not caused by lymphatic failure (Correct answer)
- Lipedema is caused by lymphatic obstruction while lymphedema is caused by fat accumulation
- Lipedema and lymphedema have identical pathophysiology but different clinical distributions
- Lipedema primarily affects the upper extremities while lymphedema primarily affects the lower
Correct answer: Lipedema involves abnormal fat deposition symmetrically in extremities and is not caused by lymphatic failure
Lipedema is a disorder of abnormal, painful subcutaneous fat deposition typically distributed symmetrically in the legs and sparing the feet, not caused by primary lymphatic failure, though it may secondarily impair lymphatics.
Question 6: What role do macrophages play in the chronic pathophysiology of lymphedema?
- They reduce fibrosis by clearing excess protein from the interstitium
- They contribute to fibrosis by releasing TGF-β and stimulating fibroblast activity (Correct answer)
- They primarily function to increase lymphatic vessel regeneration
- They have no significant role in lymphedema tissue changes
Correct answer: They contribute to fibrosis by releasing TGF-β and stimulating fibroblast activity
In chronic lymphedema, macrophages release TGF-β and other profibrotic cytokines that activate fibroblasts, leading to progressive collagen deposition and tissue fibrosis.
Question 7: Which malignancy is associated with chronic lymphedema, particularly post-mastectomy lymphedema?
- Kaposi's sarcoma
- Angiosarcoma (Stewart-Treves syndrome) (Correct answer)
- Liposarcoma
- Fibrosarcoma
Correct answer: Angiosarcoma (Stewart-Treves syndrome)
Stewart-Treves syndrome is a rare but aggressive angiosarcoma that arises in chronically lymphedematous tissue, classically in the arm following post-mastectomy lymphedema.
CLT Pathophysiology of Lymphedema 2
Primary lymphedema that is present at birth or develops within the first two years of life is classified as: