A 58-year-old man comes to the office for evaluation of a foot wound. The patient noticed a small ulcer on the bottom of his right foot a week ago but recalls no significant foot injury. He has been applying antiseptics, but the wound has failed to heal. The patient has a 15-year history of type 2 diabetes mellitus and is nonadherent to medical therapy. He has smoked a pack of cigarettes daily for 20 years. Temperature is 37.1 C (98.8 F), blood pressure is 140/80 mm Hg, and pulse is 72/min. Right lower extremity examination shows a 1-cm (0.39-in) plantar ulcer under the first metatarsal head. There are no other lesions, and the tibial and dorsalis pedis pulses are normal. Which of the following is the major inciting factor responsible for this patient's foot ulcer?

Question

A 58-year-old man comes to the office for evaluation of a foot wound.  The patient noticed a small ulcer on the bottom of his right foot a week ago but recalls no significant foot injury.  He has been applying antiseptics, but the wound has failed to heal.  The patient has a 15-year history of type 2 diabetes mellitus and is nonadherent to medical therapy.  He has smoked a pack of cigarettes daily for 20 years.  Temperature is 37.1 C (98.8 F), blood pressure is 140/80 mm Hg, and pulse is 72/min.  Right lower extremity examination shows a 1-cm (0.39-in) plantar ulcer under the first metatarsal head.  There are no other lesions, and the tibial and dorsalis pedis pulses are normal.  Which of the following is the major inciting factor responsible for this patient's foot ulcer?

Quizplus · Accepted Answer

11ec160b_3912_fe5c_9249_b1c6bc1f453d_MD0001_00 This patient has a plantar ulcer under the first metatarsal head. In a patient with chronic, poorly controlled diabetes mellitus, this is likely a neuropathic ulcer due to underlying peripheral sensory neuropathy. Chronic hyperglycemia promotes nerve injury and impairs nerve repair in distal sensory fibers, causing decreased sensation of pain, pressure, and proprioception. Loss of these protective senses can cause individuals to not recognize an injury due to minor trauma, friction, or pressure. Areas that are particularly susceptible are points of localized pressure created by a shoe or weight-bearing bones of the foot (eg, plantar surface of the first metatarsal head). A wound in this area often goes unnoticed (due to lack of pain sensation and being hidden by socks or shoes) and can develop into a nonhealing foot ulcer. Loss of proprioception and an increase in ligamentous laxity can also cause chronic pressure-induced joint/skin damage in the feet of patients with diabetic neuropathy, which can lead to calluses or foot deformities (eg, Charcot foot, hammer toe). (Choice A) Although diabetic patients (especially those who smoke) often have comorbid arterial insufficiency, arterial ulcers are typically painful, sharply demarcated, and located at the tips of the toes. This patient has full distal pulses, which makes clinically significant atherosclerotic disease unlikely to be the primary cause of the ulcer. (Choice B) Bacterial infection may delay ulcer healing, especially if there is underlying osteomyelitis, but it is not the inciting cause of neuropathic ulcers. In addition, although diabetic ulcers are often colonized by bacteria, this patient has no fever, erythema, or purulent drainage to suggest serious infection. (Choice C) Irritant contact dermatitis presents with pruritic or painful erythema in areas of exposed skin (eg, hands). It can occasionally cause small vesicles or fissures, but ulcers are not typical. (Choice E) Systemic vasculitic disorders (eg, polyarteritis nodosa) are an uncommon cause of skin ulcers. Vasculitic ulcers are usually painful and associated with other skin (eg, purpura, nodules) and systemic (eg, fever, fatigue) symptoms. (Choice F) Ulcers caused by venous insufficiency are most common over the tibias or proximal to the medial malleolus. They present as irregular ulcerations in the setting of stasis dermatitis and/or varicose veins. Educational objective: Neuropathic foot ulcers can occur in diabetic patients when loss of pain sensation and proprioception delays recognition of injury due to trauma, friction, or sustained pressure (on plantar surface of foot bones). The risk is greatest in patients with longstanding diabetes who have poor glycemic control. __________ References: The diabetic foot. (http://www.ncbi.nlm.nih.gov/pubmed/28121117)

A 58-Year-Old Man Comes to the Office for Evaluation of a Foot