A 58-year-old man comes to the emergency department due to wound dehiscence. The patient had a left subclavian catheter port placed 3 months ago to begin bevacizumab infusions for recurrent glioblastoma. The incision wound closed completely but has now partially reopened. Vital signs are normal. Examination of the left side of the chest reveals that 50% of the incision has opened; subcutaneous tissue and part of the port are visible, but there is no drainage from the wound or erythema of the surrounding skin. A complication of bevacizumab is suspected. Which of the following is the most likely primary mechanism of this patient's wound dehiscence?

Question

A 58-year-old man comes to the emergency department due to wound dehiscence.  The patient had a left subclavian catheter port placed 3 months ago to begin bevacizumab infusions for recurrent glioblastoma.  The incision wound closed completely but has now partially reopened.  Vital signs are normal.  Examination of the left side of the chest reveals that 50% of the incision has opened; subcutaneous tissue and part of the port are visible, but there is no drainage from the wound or erythema of the surrounding skin.  A complication of bevacizumab is suspected.  Which of the following is the most likely primary mechanism of this patient's wound dehiscence?

Quizplus · Accepted Answer

Wound dehiscence is partial or complete separation of previously approximated wound edges. It occurs due to disruption of the wound-healing process and may be a complication of medications such as bevacizumab. Bevacizumab is a monoclonal antibody that binds vascular endothelial growth factor (VEGF), preventing it from binding to its cell surface receptor. This inhibits angiogenesis-the process by which new blood vessels sprout from surrounding, uninjured vessels and grow into the wound-because angiogenesis is largely stimulated by VEGF. Because bevacizumab suppresses the growth of new blood vessels, it limits the blood supply to the tumor and is often referred to as cancer-starving therapy. However, because it also suppresses angiogenesis in healing wounds, it can cause wound dehiscence. The lack of angiogenesis leads to inadequate blood supply to support collagen production during the proliferation phase (3 days to 5 weeks) and collagen remodeling and cross-linking during the maturation phase (3 weeks to 2 yr). When these are inhibited, the tensile strength of the wound remains low, and dehiscence can occur even weeks to months after initial wound closure. (Choice B) Radiation therapy, commonly used in cancer treatment, causes DNA damage, resulting in apoptosis of susceptible (eg, highly proliferative) cells. However, it also damages surrounding noncancerous tissues, including local blood vessels, which can subsequently develop progressive eccentric myointimal proliferation and luminal obstruction. This can eventually result in tissue ischemia (eg, chronic skin ulcers). (Choice C) Vinca alkaloids such as vincristine and vinblastine inhibit cytoskeleton microtubule development. This results in the arrest of cell division and replication at the metaphase stage, leading to failure of division and cell death. (Choice D) Anti-inflammatory agents such as glucocorticoids can impair inflammatory cell migration to the wound site. Suppression of inflammation, the wound-healing phase that precedes proliferation, can delay the progression of wound healing. (Choice E) Vitamin C deficiency can result in inadequate hydroxylation of proline and lysine residues during collagen synthesis. Because hydroxyproline and hydroxylysine are essential for collagen cross-linking, vitamin C deficiency compromises collagen cross-linking and reduces the maximal tensile strength of the wound. Educational objective: Bevacizumab is a monoclonal antibody that inhibits the binding of vascular endothelial growth factor (VEGF) to its receptor. This inhibits angiogenesis and limits blood supply to tumors (ie, cancer-starving therapy). However, it also impairs wound healing and can lead to wound dehiscence.

A 58-Year-Old Man Comes to the Emergency Department Due to Wound