A 45-year-old Caucasian man, M.N., visits his family physician for a follow-up examination of the ulcer on his right foot. Today the patient reports that his foot feels more swollen. He has no pain, fever, or chills. Nine months ago M.N. began to exhibit a calloused, erythematous area on his right foot that subsequently became edematous and ulcerated. He was treated with cefuroxime (Ceftin) for 10 days and encouraged to stay off his feet. In a subsequent visit it was decided to refer him to a podiatrist and also to help him procure shoe inlays. The appearance of his foot infection improved for a while, then worsened. The patient was on his feet most hours of each day at his job as a baker, and this slowed his healing. His physician then treated him with cephalexin (Keflex), and he began to wear a cam walker. He failed to improve and, in fact, worsened. He was referred to an orthopedist. Plain films of his foot showed soft tissue ulceration without definite evidence of osteomyelitis. He was referred to the wound care clinic and began using Duoderm. He received yet another course of antibiotics. Wound cultures were not obtained.
Other medical history
- Diabetes mellitus type II
- Diabetic retinopathy
- Hypertension
- Erectile dysfunction
- Obesity
- Pes planus
Family history
- Diabetes and hypertension in father and paternal grandmother. Father had 2 myocardial infarctions and died at age 62. Mother is healthy. Sister has borderline diabetes.
Social history
- Nonsmoker
- 4 to 5 beers per week
- Divorced
- Works as a baker
Review of systems
- Negative except for increased swelling of right foot
Physical exam
- Alert male in no distress
- Blood pressure 135/68 mm Hg, temperature 37.5 °C, respiratory rate 14, heart rate 80, weight 236 pounds
- Heart, lung, and abdominal exam unremarkable
- Right 3rd toe has erythema at the metatarsophalangeal joint, with a draining ulcer on the plantar surface. Foot is edematous with erythema spreading proximally toward lower extremity. Erythema is <2 cm from ulcer rim. Pedal pulses are 1+, and capillary refill is <2 seconds. Monofilament testing reveals insensitivity at more than 4 sites.
Q: What is the differential diagnosis of the patient’s symptoms?
A:_______________________________________________________________
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Important elements of the history and exam
Assess vascular integrity. Arterial insufficiency is suggested by a history of cardiac or cerebrovascular disease, leg claudication, impotence, or pain in the distal foot when the patient is supine. Exam may reveal diminished or absent pulses, pallor on elevation, redness of the foot on lowering the leg, delayed capillary refill in toes, and thickened nails or absence of toe hair. With diabetes or renal impairment, the pulse exam may be unreliable due to arterial calcification.
Helpful studies may include segmental limb pressures, pulse-volume wave form, transcutaneous oxygen pressure, and ankle brachial index (which can be normal with significant calcinosis). Obtain a vascular surgery consultation immediately if you suspect arterial insufficiency, as revascularization may be necessary.1
Evaluate for musculoskeletal problems. Examine gait, look for foot deformities, and test joint range of motion. If a mechanical basis of the ulceration is found, eliminate or reduce foot pressure with shoes, inserts, orthoses, etc. Reconstructive foot surgery may be an option for some patients.
Gauge neurologic status. Most foot ulcers develop because of loss of protective sensation; therefore, screen all patients with diabetes annually for loss of protective sensation, using a 10-g nylon monofilament. Press the monofilament against the plantar skin until it buckles, hold it there for 1 second, and remove it.2 The neurologic exam can also include testing for motor strength, deeptendon reflexes, and vibratory (128-Hz tuning fork), proprioceptive, and protective sensation.
Measure the wound, watch for infection. When examining an ulcer, assess location, size, and depth. When caring for wounds, document at each visit the length and width of the wound.3 Note any signs of infection (warmth, redness, pain, tenderness, induration, pus) or gangrene. Observe for fever, chills, and leukocytosis, but do not rely on systemic symptoms as indicators of infection. Assess the severity of infection, and explore the wound for foreign or necrotic material with a sterile metal instrument.
Examine toenails for fungal infection, as this may be a significant contributor to the initiation and continuation of a foot ulcer. Callus formation, especially with hemorrhage, may be evidence of an impending ulcer.3
M.N.’s physician was increasingly concerned about the lack of healing of his ulcer. The differential diagnosis for this patient’s swollen foot includes cellulitis, osteomyelitis, gout, foreign body, arthritis, trauma, deep venous thrombosis, pseudogout, and venous insufficiency. Many of these were excluded by the physical exam. A bone scan was ordered.