Abstract
Lymphatic thrombosis is a rare occurrence, and although its frequency is likely underestimated,
its burden remains substantially lower than that of venous or arterial thrombosis.
Current evidence suggests that despite measurable levels of fibrinogen, von Willebrand
factor and other coagulation factors in the lymph, fibrin generation is substantially
inhibited under physiological conditions, essentially making the lymph a hypocoagulable
biological fluid. Although factor VIIa-tissue factor-catalyzed activation of factor
X is possible in the lymph, fibrin generation is largely counteracted by the unavailability
of cell surface anionic phospholipids such as those physiologically present on blood
platelets, combined with only low levels of coagulation factors, and the strong inhibitory
activity of heparin, antithrombin, and tissue factor pathway inhibitor. Enhanced fibrinolytic
activity further contributes to reduce the development and growth of lymph clots.
Nevertheless, lymphatic thrombosis is occasionally detected, especially in the thoracic
duct, axillary, or inguinal lymphatics. Pathogenetic mechanisms are supported by the
release of thromboplastin substances from the injured lymphatic endothelium accompanied
by chronic obstruction of lymph flow in the presence of a hypercoagulable milieu,
thereby mirroring the Virchow triad that otherwise characterizes venous thrombosis.
In theory, any source of lymphatic vessel occlusion, such as internal obliteration,
external compression, or increased lymphatic pressure, might predispose to localized
lymphatic thrombosis. The leading pathologies that can trigger thrombosis in the lymphatic
vessels include cancer (due to external compression, neoplastic obliteration of the
lymphatic lumen by metastatic cells, or lymphatic dysfunction after lymph node dissection),
infections (especially lymphatic filariasis or sustained by Chlamydia trachomatis, Mycobacterium tuberculosis, Treponema pallidum, or Streptococcus pyogenes), congestive heart failure, chronic edema and inflammation of the distal lower limb,
complications of central venous catheterization, coronary artery bypass grafting,
thoracic outlet syndrome, and amyloidosis.
Keywords
lymphatic thrombosis - vessel - lymph - coagulation
