Microlymphatics of human skin

Area of Science:

• Dermatology
• Vascular Biology
• Medical Imaging

Background:

• Human skin possesses two interconnected microlymphatic networks: a superficial network in dermal papillae and a deeper one.
• These networks play a crucial role in fluid balance and immune surveillance within the skin.

Purpose of the Study:

• To characterize the structure and function of human skin microlymphatics in health and disease.
• To investigate the role of microlymphatic abnormalities in conditions like primary lymphedema, chronic venous insufficiency, and lipedema.

Main Methods:

• Fluorescence microlymphography was employed to visualize superficial microlymphatic networks using FITC-dextran.
• Microlymphatic pressure was measured using the servo-nulling technique after vessel visualization.
• Permeability studies were conducted using different sizes of FITC-dextran molecules (40,000 and 150,000).

Main Results:

• Primary lymphedema showed enlarged microlymphatic networks compared to healthy controls.
• Congenital lymphedema (Milroy's disease) presented with aplastic or ectatic microlymphatics (>90 microns).
• Chronic venous insufficiency, lipedema, and recurrent erysipelas led to lymphatic microangiopathy with vessel obliteration.
• Healthy microlymphatics were permeable to FITC-dextran 40,000 but not 150,000; chronic venous insufficiency showed increased permeability to 150,000.
• Microlymphatic hypertension was identified as a contributing factor to edema in primary lymphedema.

Conclusions:

• Skin microlymphatic networks exhibit significant structural and functional alterations in various lymphedema subtypes.
• Abnormalities in microlymphatic permeability and pressure are implicated in the pathogenesis of lymphedema and related conditions.
• Fluorescence microlymphography and pressure measurements offer valuable insights into microlymphatic dysfunction.