Disseminated Intravascular Coagulation
Disseminated intravascular coagulation (DIC) is a serious, life-threatening condition of the blood clotting system that can be caused by myriad insults to the body. It has a grave prognosis unless caught and treated early in the course of disease. Skin manifestations occur early and continue to progress unless the patient recovers. The skin lesions may lead to gangrene and secondary infection, further worsening the prognosis. DIC is seen as an end-stage process, caused by the consumption of blood clotting factors, that results in uncontrolled clotting and bleeding occurring simultaneously.
Clinical Findings: DIC occurs in males and females with equal incidence and has no racial or ethnic predilection. DIC has a wide range of cutaneous findings. Patients are often gravely ill and hospitalized in a critical care setting. A small subset of patients with early DIC present with cutaneous findings. The remainder of patients are first diagnosed with DIC and eventually develop cutaneous manifestations. The initial cutaneous clinical appearance is that of small petechiae that enlarge and coalesce into large macules and plaques of erythema. There may be a livedo reticularis pattern to the extremities. This fishnet-like appearance can be seen in other dermatological conditions. The petechiae quickly convert to purpuric plaques. Ulceration, necrosis, and blister formation are commonly seen in the areas of involvement. As the disease progresses, gangrene may develop in the affected areas as the blood flow to the skin is significantly decreased due to clotting of various components of the vascular system. Gangrene may lead to secondary infection. The finding of gangrene indicates a grave prognosis, and most of these patients do not survive. If DIC is treated aggressively and early, the survival rate is still only 40% to 50% at best.
DIC is considered to be a consumptive coagulopathy.
The initial event that starts the reaction can be multifactorial. The most common causes of DIC are underlying malignancy (especially leukemia), severe traumatic events, sepsis, and obstetric complications. Each of these associated conditions has its own specific clinical setting. As DIC progresses, uncontrollable clotting and bleeding coexist, and patients often succumb to infection, thrombosis, or exsanguination. Thrombocytopenia is a common laboratory finding, as is an elevation of the bleeding time, prothrombin time (PT), and partial thromboplastin time (PTT). Fibrinogen is consumed, leading to an increase in fibrin degradation metabolites.
Pathogenesis: DIC may be subdivided into predominantly hemorrhagic and predominantly thrombotic types, although overlapping features of both occur in all cases. An inciting event such as trauma or infection initiates the clotting cascade in which the clotting factors are used up (or lost, in cases of severe bleeding) faster than they can be replaced. This sets off a cascade of events within the clotting system that results in consumption of all the factors used in clotting, leading to thrombosis and hemorrhage.
Histology: Examination of skin biopsies shows necrosis of the overlying epidermis and parts of the dermis. Thrombosis of the small veins and arterioles is seen, as is widespread hemorrhage. In cases of sepsis-induced DIC, evidence of the causative organism may be found in the biopsy specimen.
Treatment: Treatment requires prompt recognition of the condition and immediate supportive care. Treatment of the underlying infection is a must, and in trauma-induced cases, bleeding must be stopped and coagulation factors replaced as they are lost. The main component of therapy is treatment of the underlying cause that has precipitated the DIC event. The treatment of DIC is complicated and should be undertaken in a critical care setting. Many agents are used to help decrease thrombosis and replace lost clotting factors. A fine balance must be maintained between clotting and thrombosis. Patients with severe DIC have a poor prognosis.