Differential Diagnosis Of Foot Ulcer

The above picture is taken from a 38 year old diabetic man admitted in surgical ward for management of his foot ulcer. 

How would you approach to a case of Foot Ulcer?

A foot ulcer is an open sore on the foot. it can be shallow involving only the surface of the skin or deep extending through the full thickness of the skin. It may even involve the tendons, bones and other deep structures.

Causes: Ulcers on feet are common and may be either vascular or neuropathic in origin. 

Vascular Causes: 

1. Large Vessel Disease: 

• Arteriosclerosis
• Embolism

2. Small Vessel Disease:

• Diabetes
• Buerger's disease
• Raynaud's disease
• Embolism
• Vasculitis, e.g SLE, rheumatoid arthritis, scleroderma

Neuropathic Causes:

1. Peripheral Nerve Lesions:

• Diabetes
• Peripheral nerve injuries
• Leprosy
• Alcoholism

2. Spinal Cord Lesions:

• Spina bifida
• Tabes dorsalis
• Syringomyelia

Neoplastic Causes:

• Squamaous cell carcinoma
• Malignant melanoma

Traumatic Cause:

• Ill fitting foot wear

Infective Cause: 

• Madura Foot (rare)

History: 

1. Vascular: Ischemic ulcers are common in elderly. they are painful and donot bleedmuch. They show no sign of healing. There is often a history of intermittent claudication and rest pain. CHeck for history of diabetes. In the younger patientdiabetes, Buerger's disease or Raynaud's disease may be responsible. Check for a history of cardiac diseade, which may suggest embolism leading to ischemic ulceration. Proximal artery disease e.g aneuyrsm may also cause emboli.

2. Neuropathic: These are painless ulcers occurring over pressure points. Patients may give a history of neuropathy. They may describe a feeling as though they are walking on cotton wool. Check for history of diabetes and peripheral nerve lesions. Spinal cord lesions may also be present. In diabetes ulceration may be associated with both ischemia and neuropathy.

3. Traumatic: Foot ulcers may be caused by minor trauma e.g ill fitting shoes, however there is usually a history of an underlying condition e.g poor circulation, steroid therapy, neuropathy.

4. Infective: Pure infective ulcers on foot are rare. Fungal infections may occur with Nocardia species in tropical countries causing Madura foot. Check for history of foreign travel

Examination:

1. Ischemic ulcers are found on the tips of the toes and over pressure areas. The edge is usually punched out and healing does not occur. The base may contain slough or dead tissue. Occasionally tendons are seen in the base of the ulcer. Pulse may be absent. Check for atrial fibrillation which may be associated with embolism as a cause of ischemic ulceration. 

2. Neuropathic ulcers are deep, penetrating ulcers. They occur over pressure areas but the surrounding tissues are healthy and have good circulation. The ulcers themselves is painless. Examine the surrounding tissues for blunting of sensation e.g absence of pinprick sensation. Pulses are usually present. It is important to do a full neurological examination to look for peripheral nerve injuries or evidence of spinal cord lesions. 

3. Neoplastic ulcers like squamus cell carcinoma have an everted edge, often with necrotic material in the base of the ulcer. The edge of the ulcer is hard. Check for inguinal lymphadenopathy.

Ulcers associated with malignant melanomatend to vary in color from brown to black, although they may be amelanotic. Bleeding and infection may cause the surface of the tumor appear wet, soft and boggy. Check for inguinal lymohadenopathy and hepatomegaly. 

4. Traumatic ulcers tend to occur either at pressure points , due to an ill fitting foot wear , or at a site of injury. They usually have sloping edges and granulation tissue developing in the base. Always check the circulation, as most traumatic foot ulcers readily heal unless there is an abnormality in circulation. 

5. Infective ulcers by themselves are rare. Secondary infection may occur on any type of ulcer. With Maduara foot there may be ulceration and bone destruction with little systemic illness. 

 Investigations: 

• Complete Blood Count ( decreased Hb may indicate malignancy, Increased White cell count indicates infection)
• Blood sugar for diabetes
• Swab from the ulcer for microscopy and C/S
• Doppler studies in cases of ischemic ulcer
• Nerve conduction studies for neuropathic ulcers
• Biopsy to rule out malignancy.