Where do lymph and tissue fluid accumulate in lymphedema of the lower limbs caused by obliteration of lymphatic collectors?

Obliteration of lymphatic collecting trunks of limbs by infective processes, trauma, oncologic surgery and irradiation bring about retention of lymph and tissue fluid in tissues. Knowledge as to where excess lymph is produced and accumulates as tissue fluid is indispensable for rational physical therapy. So far, this knowledge has been based on lymphoscintigraphic, ultrasonographic and MR images. None of these modalities provides distinct images of dilated lymphatics and fluid expanded tissue spaces in dermis, subcutis and muscles. Only anatomical dissection and histological processing of biopsy material can demonstrate the remnants of the lymphatic network and the sites of accumulation of mobile tissue fluid. We visualized and calculated the volume of the "tissue fluid and lymph" space in skin and subcutaneous tissue of foot, calf, and thigh in various stages of lymphedema, using special coloring techniques in specimens obtained during lymphatic microsurgical procedures or tissue debulking. When the collecting trunks were obliterated, lymph was present only in the subepidermal lymphatics, while mobile tissue fluid accumulated in the spontaneously formed spaces in the subcutaneous tissue, around small veins, and in the muscular fascia. Deformation of subcutaneous tissue by free fluid led to formation of interconnecting channels. In obstructive lymphedema caused by obliteration of collectors, lymph is present mainly in subepidermal lymphatics, and the bulk of stagnant tissue fluid accumulates in subcutis between fibrous septa and fat globules as well as above and underneath muscular fascia. These observations provide useful clues for designing pneumatic devices and rational manual lymphatic massage to move stagnant tissue fluid toward the non-swollen regions.