Chapter 222: Dry Gangrene

PATIENT STORY

A 36-year-old woman with type 1 diabetes presented with a 4-week history of a dry, black great toe and third toe on the right foot (Figure 222-1). She said that she noticed severe maceration between the first and second interspace approximately 6 weeks ago. Subsequently, the toes changed color and became very painful. Two days ago, she noticed a foul odor from both toes. The patient reported smoking since she was 13 years old. On physical examination, there were no palpable pulses in the right foot. The patient was admitted for IV antibiotics and revascularization was performed. Subsequently, the toes were partially amputated and the wounds healed without any complications. Her physicians attempted to help her to quit smoking and she enrolled in a smoking cessation program.

INTRODUCTION

Dry gangrene develops following arterial obstruction and appears as dark brown/black dry tissue. Peripheral arterial disease is common in patients with diabetes, smoking history, and dyslipidemia. Dry gangrene is most commonly seen on the toes. The nonviable tissue becomes black in color from the iron sulfide released by the hemoglobin in the lysed red blood cells.

SYNONYMS

Mummification necrosis.

EPIDEMIOLOGY

• Peripheral arterial disease (PAD) is a common finding in patients with diabetes and is an important factor leading to lower-extremity amputation in patients with diabetes.¹

• Thirty percent of diabetic patients with an absent pedal pulse will have some degree of coronary artery disease.¹

ETIOLOGY AND PATHOPHYSIOLOGY

• PAD manifests in the lower extremity in two ways: macro- and microvascular diseases.

• The pattern of occlusion in the macrovascular tree is distal and multisegmental in the diabetic population.² In the nondiabetic population, the pattern of occlusion occurs proximal to the knee joint.

• In the diabetic population, multiple occlusions occur below the trifurcation of the popliteal artery into the anterior tibial artery, posterior tibial artery, and peroneal artery.

• Risk factors, such as hypercholesterolemia, hyperlipidemia, and hypertension, are often associated with patients with PAD.^3,4

RISK FACTORS

• Diabetes.

• Dyslipidemia.

• Smoking.

• Neuropathy.

DIAGNOSIS

CLINICAL FEATURES

• Dry, black eschar, which most commonly begins distally at the extremities (Figures 222-1 and 222-2).

• There is a clear demarcation between healthy tissue and necrotic tissue (see Figures 222-1 and 222-2).

• Foul odor.

• Pain may be present.

• Trauma is the most common etiology.

• Nonpalpable pulses are common. ...