Q. A 53-year-old paraplegic man is brought to the physician’s office for a bleeding ulcer on his left hip for the past 1 month. He says that the ulcer has been there for the past 15 years and it was small. But recently he has noticed an increase in the size of the ulcer and also the dressing pad is frequently getting soaked with blood. His medical history shows that he has been suffering from paraplegia secondary to traumatic transverse myelitis for the past 20 years. His temperature is 98.4°F (36.9°C), pulse is 87/min, blood pressure is 130/70 mmHg, and respirations are 15/min. Physical examination shows a left ischial pressure ulcer of size 1x1 cm involving full-thickness skin loss and extending into the deep subcutaneous tissue. The ulcer has thick granulation tissue with raised margins and it bleeds on touch. Sample from ulcer has been collected for histopathological examination. This patient is at the highest risk for which of the following conditions?