A 58-year-old man comes to the urgent care center with a 2-week history of an ulcer on his right foot. He recalls no injury and found a "dime sized" ulcer on the bottom of the foot after noticing soakage on his sock. The patient has been cleaning the wound with antiseptics and applying topical antibiotics, but it has failed to heal. He has had no pain, surrounding redness, fever, or chills. The patient was diagnosed with hypertension several years ago but had no follow-up with a physician. He takes ibuprofen for occasional back pain. The patient has a 30-pack-year smoking history and drinks 1 or 2 beers daily. He works in a warehouse, where he is "constantly on the move" and considers himself to be in good health. Temperature is 36.7 C (98.1 F), blood pressure is 156/98 mm Hg, and pulse is 88/min. BMI is 32 kg/m². On examination, the feet are warm and dry. A 2-cm nontender ulcer is present on the sole of the foot just below the head of the first metatarsal bone. There is scant discharge and necrotic tissue at the ulcer bed, but the bone probe is negative. Which of the following will most likely diagnose the underlying cause of this patient's foot ulcer?

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11ec25c8_d861_fcba_bc81_852c5cb4c725_MD0003_00 Neuropathic ulcers are caused by repeated pressure, friction, or trauma due to lack of sensation in the local tissues. They typically occur at weight-bearing sites (eg, head of the first metatarsal) on the sole of the foot. The location of this patient's ulcer and the lack of associated pain are consistent with a neuropathic ulcer. sole of the foot Diabetes mellitus is the most common cause of neuropathic ulcers. Whereas neuropathy involving small nerve fibers typically causes pain and paresthesia, involvement of large fibers produces sensory loss that can allow minor injuries to go unrecognized until the development of an ulcer. Associated autonomic dysregulation can lead to decreased sweating and skin fissuring and further increase the risk for ulceration. In addition to the ulcer, this patient has other risk factors for diabetes (eg, obesity, hypertension). Peripheral neuropathy can be present at the time of type 2 diabetes mellitus diagnosis in some patients and can often be asymptomatic. He should therefore be screened for diabetes with a hemoglobin A1c or fasting glucose measurement. (Choice A) The ankle-brachial index can diagnose peripheral artery disease. Features suggesting an arterial ulcer include location at the tips of the digits (least perfused areas); cool, pale skin with dermal atrophy; and diminished pulses. Unlike this patient's ulcer, arterial ulcers are typically painful. arterial ulcer (Choice B) Culture from an ulcer bed typically finds polymicrobial colonization but does not indicate true infection in the absence of more specific symptoms (eg, fever, erythema, purulent drainage) and would not establish the underlying cause of the ulcer. (Choice C) Duplex ultrasonography can identify venous insufficiency or obstruction. Venous ulcers typically occur on the medial aspect of the leg above the malleolus and are usually associated with edema and stasis dermatitis. Venous ulcers (Choice E) MRI of the spine is used in evaluation of lumbosacral radiculopathy, which typically presents with pain in the low back that radiates to the foot. This patient has no radicular pain, and radiculopathy is not a common cause of neuropathic ulcers. (Choice F) Vasculitic ulcers (eg, cryoglobulinemia, granulomatosis with polyangiitis) are typically painful and are usually associated with additional skin features, such as nonblanching petechiae or purpura. Educational objective: Neuropathic ulcers are caused by repeated pressure, friction, or trauma due to lack of sensation in the local tissues. They typically occur at weight-bearing sites on the sole of the foot. Diabetes mellitus is the most common cause of neuropathic ulcers.

A 58-Year-Old Man Comes to the Urgent Care Center with a 2-Week