Patient details
- Name
- Mr S.Q.
- Age / sex
- 58-year-old man
- Occupation
- Shopkeeper
- Marital status
- Married
- Admitted
- Emergency department, 10:20
- Clerked
- Surgical ward, 11:30
- Source
- Patient and his wife, reliable
- Referred by
- Diabetes clinic
Presenting complaint
“A wound on the sole of my right foot that has not healed for six weeks.”
History of presenting complaint
Mr S.Q. has had type 2 diabetes for 15 years. Six weeks before admission, after a day spent standing in new shoes, he found a stain on his right sock and then a blister on the sole of the right foot beneath the base of the great toe. He had felt nothing. The blister burst and left an open wound, which has slowly enlarged in spite of dressings he applied at home, and it has remained painless throughout. Five days ago a yellow, foul-smelling discharge began, and redness and swelling have since spread onto the top of the foot. For two days he has felt feverish, with one attack of shivering yesterday, and his home glucose readings have risen above 300 mg/dL on his usual treatment. For three years he has had numbness and a burning, tingling feeling in both feet, worse at night, and he says walking feels like stepping on cotton. He can walk 500 metres to the mosque without pain in his calves, and has no pain in the feet at night. He had an ulcer on the left great toe two years ago, which healed with dressings over three months, and has had no amputation. He walks barefoot at home, does not check his feet and has never seen a foot care specialist. He does not remember stepping on anything sharp. His last HbA1c, four months ago, was 10.2%, and he declined insulin when it was advised. He had laser treatment to both eyes last year and has been told there is protein in his urine. He has had no swelling of the legs, varicose veins or clots in the leg veins.
Past medical history
Type 2 diabetes for 15 years. Hypertension for ten years. Raised cholesterol. No known heart disease or stroke.
Past surgical history
No previous operations.
Drugs and allergies
Metformin 1 g twice daily. Glimepiride 4 mg once daily. Enalapril 10 mg once daily. Atorvastatin 20 mg at night.
No known drug allergies. Tetanus vaccination status not known.
Family history
Both parents had diabetes. His father had a below-knee amputation.
Social history
Smokes 20 cigarettes a day for 30 years (30 pack-years). No alcohol. Stands for most of the working day. Wears open sandals.
Last ate at 08:00 today.
General examination
A heavy man who looks unwell and flushed. Alert and orientated. Not pale. Tongue dry.
Urine dipstick: glucose 3+, protein 2+, ketones negative.
Examination of the feet
Both legs exposed to the knees, shoes and socks removed, feet compared, and the shoes inspected.
Inspection
Right foot: an ulcer on the sole beneath the head of the first metatarsal, round, 3 by 2.5 cm. The edge is punched-out and surrounded by thick callus. The base is covered with yellow slough with some red granulation tissue. It is about 1 cm deep and discharges thick, foul-smelling pus. Redness extends 4 cm from the ulcer onto the top of the forefoot, which is swollen. No black tissue, no blisters, no red streaks up the leg. Between the toes the skin is intact.
Both feet: toes clawed, skin dry and cracked, callus beneath the left first metatarsal head, healed scar on the left great toe. The arches are preserved. No varicose veins and no brown staining at the ankles.
Palpation
The right forefoot is warm and swollen. There is no pain on pressing around the ulcer. No crackling under the skin. A sterile probe passed into the ulcer touches bone. Tender enlarged lymph nodes in the right groin.
Pulses
Femoral and popliteal pulses present on both sides. Right dorsalis pedis present, posterior tibial weak. Left both present. Capillary refill two seconds in both great toes.
Sensation
A 10-gram monofilament is not felt at 6 of 10 sites on the right foot and 5 of 10 on the left. Vibration from a tuning fork is not felt at the great toes or ankles and is felt at the knees. Ankle reflexes absent on both sides.
Footwear
Open sandals with a worn insole. No foreign body.
Other systems
Chest: clear.
Heart: first and second heart sounds normal, no murmurs.
Abdomen: soft, no masses.
Eyes: reduced vision in both eyes, by his own account.
Summary
Provisional diagnosis
Infected neuropathic ulcer of the right foot with probable infection of the underlying bone and systemic infection, in poorly controlled type 2 diabetes. Blood supply clinically adequate.
Initial plan
- Admit. No weight on the right foot.
- Bloods: full blood count, C-reactive protein, urea and creatinine, glucose, HbA1c, blood cultures.
- X-ray of the foot. Assessment of blood supply with ankle or toe pressures.
- Intravenous antibiotics according to protocol, after cultures.
- Insulin to control the glucose. Intravenous fluids.
- Urgent senior review for surgical drainage and removal of dead tissue, with deep tissue sent for culture.
- Tetanus cover. Referral to the diabetic foot team.
Differential diagnosis of an ulcer on the leg or foot
Group ulcers by cause: nerve, artery, vein and others. Site, pain and edge separate them. Then, for a hot swollen diabetic foot, list what else it can be.
| Diagnosis | Points to it in the history | Points to it on examination | In this patient |
|---|---|---|---|
| By cause | |||
| Neuropathic ulcer | Diabetes for years, numb feet, painless | On a pressure point of the sole, punched-out with callus, warm foot, pulses present, sensation lost | Most likely |
| Arterial ulcer | Calf pain on walking, foot pain at night eased by hanging the leg down, smoker | Toe tips, heel or between the toes; very painful, pale base, cold foot, absent pulses | No pain, pulses present |
| Mixed nerve and artery ulcer | Diabetic with both sets of symptoms | Features of both; the commonest reason for failure to heal | Pressures will be measured |
| Venous ulcer | Varicose veins, previous vein clot, aching swollen legs | Above the inner ankle, shallow with a sloping edge, brown stained hardened skin | Wrong site, no vein disease |
| Pressure ulcer | Bedbound or paralysed patient | Heel or sacrum, over bone | Walks normally |
| Other causes | |||
| Cancer in a long-standing ulcer | Ulcer or scar present for years that changes | Raised, rolled-out edge, hard nodes | Six weeks only; biopsy if it fails to heal |
| Melanoma of the sole | A dark or pink patch that bleeds | Irregular pigmented or pale lesion, not on a pressure point | Typical site and callus for a pressure ulcer |
| Cutaneous leishmaniasis | Lives in or visited an affected area, sandfly bite, sore for months | Painless ulcer with a raised edge on exposed skin, often the leg or face | Sole of the foot, with diabetes |
| Vasculitis or rheumatoid disease | Joint disease, several painful ulcers | Multiple small punched-out ulcers on the lower leg | Single, painless |
| Pyoderma gangrenosum | Inflammatory bowel disease, rapidly enlarging painful ulcer | Purple overhanging edge | Painless |
| The hot swollen diabetic foot | |||
| Charcot foot | Numb foot, minor injury, swelling over weeks, little pain | Hot, red, swollen mid-foot, later a collapsed arch; no ulcer, no fever | Arch preserved, ulcer present |
| Cellulitis without ulcer | Break in the skin, often between the toes | Red, hot, tender skin with fever | There is a deep ulcer |
| Gout | Sudden severe pain in the great toe joint | Red, exquisitely tender joint | Painless |
| Deep vein thrombosis | Swelling of the whole calf, immobility | Swollen warm calf | Swelling limited to the forefoot |
Clinical signs related to this case
The signs you should look for in any patient with a foot or leg ulcer. For each one, know how to elicit it and what a positive result means.
| Sign | How to elicit it, or what you see | What it means |
|---|---|---|
| Describing the ulcer | ||
| Sloping edge | The edge slopes gently to the base, with a bluish rim of new skin | A healing ulcer; typical of venous ulcers |
| Punched-out edge | The edge drops straight down | Neuropathic or arterial ulcer |
| Undermined edge | The skin overhangs the base | Pressure ulcer, tuberculosis, pyoderma gangrenosum |
| Rolled or raised everted edge | The edge is heaped up; pearly and rolled in, or turned outwards | Skin cancer |
| Base | Red granulation: healing. Yellow slough: dead tissue. Black: dead skin. Tendon or bone visible: deep. | Tells the depth and the stage of healing |
| Signs of nerve damage | ||
| Monofilament not felt | A 10-gram filament pressed until it bends, at set points on the sole, eyes closed | Protective sensation is lost: the foot is at risk |
| Vibration not felt | Tuning fork on the tip of the great toe, then the ankle | Early sign of nerve damage |
| Absent ankle reflex | Tap the tendon with the patient kneeling or the foot held up | Nerve damage |
| Clawed toes, high arch, callus | Look at both feet from above and below | Small muscles of the foot are wasted and pressure falls on the metatarsal heads |
| Collapsed arch with a rounded sole | Compare both feet standing | Charcot foot: the joints have been destroyed |
| Signs of poor blood supply | ||
| Absent foot pulses | Dorsalis pedis and posterior tibial on both sides | Arterial disease. Present pulses do not exclude it in a diabetic. |
| Cold foot, hairless shiny skin, slow capillary refill | Compare both feet | Long-standing poor supply |
| Buerger's test | Foot turns white on raising and dusky red on hanging down | Severe arterial disease |
| Dry black toe | Hard, dry, shrunken, with a clear line | Dry gangrene from loss of blood supply |
| Signs of infection | ||
| Spreading redness, warmth and swelling | Mark the edge with a pen and time it | Cellulitis; the mark shows whether it is advancing |
| Probe touches bone | Sterile blunt probe passed gently to the base | Bone infection is likely |
| Crackling under the skin | Felt on gentle pressure | Gas in the tissues: a surgical emergency |
| Wet, black, foul-smelling tissue | Swollen, moist, with no clear line | Wet gangrene with infection: urgent surgery |
| Red streaks and tender groin nodes | Look up the leg and feel the groin | Infection spreading through the lymph channels |
| Signs of venous disease | ||
| Brown staining and hard skin above the ankle | With varicose veins and swelling | Long-standing high pressure in the veins |
Teaching case. The patient is fictional and written to illustrate format and reasoning. Local protocols decide investigation and treatment.