Dermal Lymphatics

Microneedles, 0.2 mm o.d., were connected to a microsyringe and mounted on a micromanipulator. Under microscopic control, 0.01 ml of a 25% solution of FITC-labeled dextran-40 or dextran-150 were injected into the subepidermis at the big toe near the nailfold or in the medial ankle region. Fluorescence intravital microscopy revealed a network of lymphatic microvessels. The comparison with recent anatomic studies reveals that the reticular network visualized by FITC-dextran corresponds to the network in the stratum papillare. In 20 healthy subjects lymphatic capillaries were detected in a restricted area on the lateral aspect of the big toe. In 10 patients with primary lymphedema, the dye expanded to almost the entire dorsal skin surface of the big toe. In two cases, enlarged and tortuous microvessels of pathologic shape were observed. Fluorescence microlymphography is a simple and nearly atraumatic approach for depicting the intravital anatomy of human skin lymphatic capillaries.

Postmastectomy oedema (PMO) of the arm is a common aftermath of axillary lymphatic damage during treatment for breast cancer. The aim of the present study was to quantify the forearm dermal lymphatic capillaries in order to determine whether they exhibit adaptive responses to PMO. Both forearms were examined by fluorescence microlymphography in 16 patients with oedema following treatment for breast cancer (mean swelling 25 ± 4%) and 19 patients treated for breast cancer but without oedema. Delineated lymphatic networks were analysed stereologically. The main findings were: (1) lymphatic density at any specified distance from the injection site was greater in the swollen arm than the control arm (p < 0.01, t test); (2) taking into account the increased skin area, the total length of lymphatic capillaries in a 1-cm annulus of skin was 676 ± 56 cm (swollen), compared with 385 ± 30 cm (control) (p < 0.001, t test); (3) fluorescent marker was transported over a greater distance before draining deep in the swollen arm (2.74 ± 0.33 cm) than in the control arm (1.59 ± 0.24 cm) (p = 0.02); (4) there was no evidence of lymphatic dilatation in the swollen arm, and (5) in breast cancer patients without swelling, the arm on the side of radiotherapy/surgery (otherwise referred to as the unswollen arm) showed none of the above changes, indicating that the changes are linked to the oedema rather than being universal responses to breast cancer or its treatment. It is concluded that microlymphatic changes occur in the swollen arm, namely a local superficial rerouting of lymph drainage and either lymphangiogenesis and/or increased recruitment of dormant lymphatic vessels. Since blood capillary angiogenesis occurs in the swollen arms, and lymphangiogenesis occurs in experimental lymphoedema, there is a precedent for proposing lymphangiogenesis in PMO. An increased number of functional vessels would help to maintain the ratio of local tissue drainage capacity to filtration capacity.