Jane is an eighteen-year-old college freshman dressed in shorts who is playing a game of touch football on a grass field when she stumbles. She lands on a broken beer bottle and suffers a laceration on the dorsal surface of her thigh. Her friends suggest that she visit student health, but she has an examination in the afternoon. She washes the wound, places several large gauze pads on it. and wraps it to stop bleeding. She changes the pads every day, but five days after receiving the injury she notes some pus on the surface of the eschar and an exophytic growing mass of tissue (FIGURE 5-11). Alarmed, she visits the health service. The physician explains she has developed a minor infection in the wound. The mass is composed of granulation tissue, an excessive amount of what is a normal part of the healing process. However, because of the infection and large mass of granulation tissue, the physician debrides the wound. He explains that because she did not immediately seek medical attention and have the wound sutured she is likely to be left with a large scar.
Discussion
During wound healing, granulation tissue is the matrix in which new blood vessels form and in which fibroblasts proliferate to produce collagen, a process termed fibrosis (scar formation). Figure 5-11 (inset) shows an area rich in the formation of small capillaries oriented upward toward the wound surface. In addition, many mononuclear inflammatory cells and the elongated nuclei of fibroblasts are present. In cases where wound healing is delayed (as it was by infection in Case 5-1), cytokine production by inflammatory cells may promote the growth of excessive granulation tissue that can gape above the wound (sometimes termed proud flesh). With time, the granulation tissue will be replaced by a large scar. This form of healing of a large unsutured wound is termed secondary union. Sutured wounds oppose the injured surfaces, leaving little space for granulation tissue to form. Such healing by primary union leaves a small scar (FIGURE 5-12). Plastic and reconstructive surgeons go to great effort to carefully suture wounds to minimize scarring and to produce esthetically satisfactory results.
Figure 5-11
Figure 5-12
Etiology and Pathogenesis
The etiology is traumatic injury (laceration) resulting in superficial bacterial infection. The pathogenesis demonstrates healing of a wound by secondary union combined with excess production of granulation tissue.
Questions
1. Suppose Jane had immediately sough medical attention. What steps might the physician have taken in treating the wound?
2. Granulation tissue consists of mononuclear inflammatory cells, fibroblasts, and new capillaries. What role does each play in wound healing?
3. Careful examination of Figure 5-11 might disclose some neutrophils in the wound bed. Why do you think this is likely?