Mecanismos de Operación

Although leg ulcers can have various etiologies (see Table 1), most (72%) are due to venous insufficiency, 6% are due to pure arterial disease, and 22% are secondary to mixed venous=arterial etiology (1,3). Neuropathic ulcers are a common cause of lower extremity ulcers, principally occurring on the feet. Diabetes is the major contributor of neuropathic foot ulcers (4).

Table 1 Causes of Leg Ulcers

I. Vascular diseases V. Trauma

A. Venous A. Pressure

B. Arterial B. Cold injury (frostbite, pernio) 1. Atherosclerosis C. Radiation dermatitis

2. Arteriovenous malformation D. Burns (thermal, chemical) 3. Cholesterol embolism E. Factitia

C. Vasculitis VI. Neoplastis 1. Small vessel A. Epitheliomas

a. Hypersensitivity vasculitis 1. Squamous cell carcinoma b. Rheumatoid arthritis 2. Basal cell carcinoma

c. Lupus erythematosus B. Sarcoma (e.g., Kaposi’s sarcoma) d. Scleroderma C. Lymphoproliferative

e. Sjogren’s syndrome 1. Lymphoma

f. Behcet’s disease 2. Cutaneous T-cell lymphoma g. Atrophie blanche D. Metastatic tumors

2. Medium and large vessel VII. Infection a. Polyarteritis nodosa A. Bacterial b. Nodular vasculitis 1. Furuncle c. Wegener’s granulomatosis 2. Ecthyma

D. Lymphatics 3. Ecthyma gangrenosum E. Lymphedema 4. Septic emboli

II. Neuropathic 5. Gram-negative infections A. Diabetes 6. Anaerobic infections

B. Tabes dorsalis 7. Mycobacterial (typical and atypical) C. Syringomyelia 8. Spirochetal

III. Metabolic B. Fungal

A. Diabetes 1. Majocchi’s granuloma B. Gout 2. Deep fungal infections C. Prolidase deficiency

D. Gaucher’s disease

C. Protozoal IV. Hematologic diseases

D. Leishmania A. Red blood cell disorders

E. Infestations and bites 1. Sickle cell anemia

VIII. Panniculitis 2. Hereditary spherocytosis

A. Weber–Christian disease 3. Thalassemia

B. Pancreatic fat necrosis 4. Polycythemia rubra vera

C. Necrobiosis lipoidica B. White blood cell disorders

IX. Pyoderma gangrenosum C. Dysproteinemias

3.1. Venous Ulcers

There are an estimated 600,000–2.5 million venous leg ulcers in the United States (2). Most (85%) of the affected patients are over 65 years old (5). There is a slight female predominance (1.6:1) (6). Patients with chronic venous insufficiency (CVI) are older, obese, male, with a history of phlebitis, and a history of severe leg injury. This sug- gests that prior deep vein thrombosis, either clinical or subclinical, may be a predis- posing factor for CVI (3). Factors predicting poor healing include large wound area, long ulcer duration, fibrin covering over 50% of the wound surface, a low ankle- brachial pressure index (<0.8), and a history of venous stripping or ligation and a history of hip or knee replacement surgery (7).

Common complaints of venous disease include limb heaviness and aching that is accompanied by swelling and exacerbated by standing. Lower extremity swelling is usually worse at the end of the day, and often is alleviated with leg elevation (1). Patients may complain of odor, copious drainage, and pruritic surrounding skin. The majority of patients with venous ulcers complain of pain, which can significantly diminish their quality of life. The size of the ulcer does not correlate with the amount of pain, small ulcers in a background of atrophie blanche can often be extremely painful. Allergy to a wide variety of topical medications may also be present in the history (8).

3.2. Arterial Ulcers

The age-adjusted prevalence of peripheral arterial disease is approximately 12% (9). Major risk factors for peripheral arterial disease include cigarette smoking, diabetes mellitus, hyperlipidemia, and age over 40 years (9). Patients are usually middle-aged to elderly and men are often affected more frequently than women. Other risk factors for the development of an arterial ulcer include sedentary lifestyle, hypertension,

Table 2 Comparison of Clinical Findings in Common Leg Ulcers

Venous Arterial

Neuropathic= diabetic Location Malleolar regions Pressure sites

Distal points (toes) Bony prominences

Pressure sites (foot)

Morphology Irregular borders Necrotic base ‘‘Punched out,’’ deep

‘‘Punched out’’ Undermined edge Surrounding skin Hemosiderin

pigmentation Lipodermatosclerosis

Shiny atrophic skin with hair loss

Thick callus Other physical examination findings Varicosities Leg=ankle edema  Eczema  Lymphedema Weak=absent peripheral pulses

Prolonged capillary refill time

Pallor on leg elevation

Neuropathy with insensitivity Charcot joints Hammertoes

Source: Adapted from Kanj LF, Phillips TJ. Management of leg ulcers. Fitzpatrick’s J Clin Dermatol 1994; 52–60.

hyperhomocysteinemia, atherosclerosis, thrombosis, trauma, vasospastic diseases, and a family history of arterial ulcers or premature ischemic heart disease (9). Arterial ulcers are usually severely painful. A history of intermittent claudication in one or both legs, defined as severe pain, numbness, or paresthesia with walking or other activity and relieved with rest may be present. These symptoms usually affect the calves, but can occur anywhere on the leg (including the thighs or buttocks). In more advanced arterial disease, patients may suffer from rest pain, especially in the distal foot and toes. The pain is usually aggravated by elevation and relieved by dependency (9). 3.3. Neuropathic Ulcers

The most common etiology of neuropathic foot ulcers in the United States is diabetes. Of the 16 million affected diabetic patients in the United States, it is estimated that 20% will develop an ulcerated foot during their lifetime (10). Of patients affected by a diabetic neuropathic foot ulcer, 14–24% will require an amputation (11). Diabetes is the primary cause (85%) of nontraumatic lower extremity amputations in the United States (12).

A history that includes symptoms of neuropathy in the feet (burning, numbness, tingling, needlelike pain and=or paresthesias) should make one consider the diagnosis of diabetes. However, neuropathic ulcers are often asymptomatic (1). More rare, non- diabetic causes of neuropathy include spinal cord lesions, alcohol, and leprosy.

If the patient is diabetic, one should inquire about the quality of control of his or her diabetic disease. HbA1Clevels are a good indicator of glycemic control over

the previous 90 days. Well-controlled diabetics have HbA1Clevels between 7% and

8%. Progressive neuropathic and nephropathic changes are associated with HbA1C

levels > 9%. (13). Wound healing and infection control are impaired when HbA1C

levels approach over 12%, since leukocytic functions such as chemotaxis, adherence, phagocytosis, and intracellular bactericidal activity are altered (14). Risk factors for diabetic foot ulcers include a long history ( > 10 years) of uncontrolled or poorly controlled diabetes, which may be associated with impaired vision or blindness, neu- ropathy, nephropathy, peripheral vascular disease, history of previous foot ulcers, structural foot abnormalities, poorly fitting footware, poor foot hygiene, a history of amputation, noncompliance, and male gender (4,12,15).

4. VARIOUS ATYPICAL CAUSES OF LEG ULCERS