Differentials
Venous leg ulcer
SIGNS / SYMPTOMS
Generally occurs in the gaiter area of the leg (i.e., below the knee, above the malleoli), and rarely occurs on the dorsum of the foot.
May have surrounding lipodermatosclerosis (i.e., skin thickening and discoloration due to inflammation, scarring, and haemosiderin deposition).
INVESTIGATIONS
Ultrasound or venous plethysmography: can confirm venous incompetence, which makes this diagnosis more likely; however, venous leg ulcers can occasionally occur in the setting of a competent superficial venous system.
Gout
SIGNS / SYMPTOMS
May be associated with pain, swelling, and erythema in the forefoot, but is not generally adjacent to a foot ulcer. May occur in the setting of previous history of gout or secondary to open gout.
INVESTIGATIONS
Plain x-ray of foot: shows radiographic signs of gout (i.e., joint space narrowing, periarticular erosions, tophaceous arthritis).
Acute Charcot's neuro-osteoarthropathy
SIGNS / SYMPTOMS
May cause pain, erythema, and swelling.
May not be associated with a foot ulcer.
INVESTIGATIONS
Plain x-ray: may show cortical destruction, bony fragmentation, fractures, dislocation, and structural abnormalities of the foot. A normal x-ray does not rule out Charcot's neuro-osteoarthropathy.
MRI of foot: shows structural abnormalities of bone fracture and dislocation and, in active Charcot, bone marrow oedema.
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