Typical coagulation anomalies

Depending on the type and size of the vascular anomaly, there are typical kinds of coagulation anomalies associated with vascular anomalies:

  • Constant local activation of coagulation by stagnant blood within a slow-flow malformation (localized intravascular coagulation, LIC). This mainly affects large-volume venous malformations and, very rarely, acutely hemorrhaged large lymphatic malformations.
  • Platelet activation and consumption with concomitant coagulation activation in certain vascular tumors with marked deep thrombocytopenia (Kasabach-Merritt phenomenon, KMP). This mainly concerns the two semi-malignant vascular tumors kaposiform hemangioendothelioma (KHE) and the histologically very similar tufted angioma (TA).
  • A very rare special case is multifocal lymphangioendotheliomatosis with thrombocytopenia (MLT), also called cutaneovisceral angiomatosis with thrombocytopenia (CAT), involving disseminated, mostly very small, partly exophytic reddish vascular tumors (with lymphatic vessel endothelium) on the skin and always simultaneously in the gastrointestinal tract, which may also lead to severe thrombocytopenia.

Large venous malformations (VM) in an intramuscular location consist of blood-filled endothelium-lined cavities with dysplastic endothelium and dysfunctional vessel wall in the lesion. The blood contained within shows virtually no flow or complete stasis of the blood. This leads to permanent, ongoing formation of small microthrombi in the form of small blood clots and, at the same time, as a physiologic counterbalance, to secondary activated fibrinolysis. This is expressed clinically as ongoing localized intravascular coagulation (LIC) within the venous malformation. Localized coagulation activation in the vascular anomaly, with thrombin formation and intravascular fibrin deposition, results in counterbalancing secondary hyperfibrinolysis and consumption of coagulation factors, especially the coagulation components fibrinogen, factor XIII, and antiplasmin.

These localized coagulation processes within the venous malformation also give rise to larger local thrombi, leading to frequent painful thrombophlebitis within the venous malformation. Chronic thrombophlebitis results in the formation of phleboliths that are typical of venous malformations. These may arise through normal remodeling processes over time from thrombi that slowly organize during degradation via collagen deposition. These then form a consecutive spherical or popcorn-like calcification (= phlebolith) via an increasing, shell-like attachment of calcium.

The following overview table summarizes the important coagulation phenomena:

 Kasabach-Merritt phenomenon (KMP)LIC/DIC
PatientInfant with hard, reddish-bluish vascular tumorAdolescent/young adult with large-volume VM on extremity or trunk
Associated vascular anomalyKaposiform hemangioendothelioma (KHE) / tufted angioma (TA)Venous malformation (VM)
FrequencyUp to 45% in the first year of life with KHE/TA40%-58% of all patients with very large VM
Laboratory constellationThrombocytes ↓ ↓ ↓ ↓
D-dimers ↑ ↑
Fibrinogen (↓)
D-dimers ↑ ↑ ↑
Fibrinogen ↓ ↓
Thrombocytes (↓)
CausePlatelet activation at dysplastic tumor endothelium with trapping, secondary clot activationActivation of plasmatic coagulation by stasis in large, stagnant blood-filled cavities of venous malformation, impaired endothelial function
Risk of worseningAdministration of platelet concentrates – immediate consumption, inflammationFurther clot activation due to open surgery, sclerotherapy, trauma, immobilization, etc., – switch to DIC
ProphylaxisHeparin, ASA, possibly ticlopidineHeparin (already at least 3 days before major planned interventions)
TherapyTransarterial embolization of the tumor, compression therapy, heparin, ASA, ticlopidine, sirolimus, surgery if necessaryHeparin, if necessary
Coagulation factor substitution
Compression therapy, sclerotherapy and surgery if necessary