A 52-year-old woman is brought to the emergency department due to a day of fever, lethargy, and skin lesions. She is currently undergoing combination chemotherapy for diffuse large B-cell lymphoma, and her last treatment was 10 days ago. Yesterday, the patient developed a red rash on her right thigh. Within a few hours, a pustule formed in the center of the lesion, rapidly evolved into a dark bulla, and then ruptured and formed an ulcer. A second, similar skin lesion arose shortly thereafter. The patient has also had fever and chills and progressive weakness and lethargy. Temperature is 38.9 C (102 F) , blood pressure is 110/60 mm Hg, and pulse is 106/min. She has an implanted central venous catheter with a subcutaneous port; the overlying skin is not erythematous or tender. Cardiopulmonary auscultation reveals clear lung fields and no cardiac murmurs. The abdomen is soft and nontender. Skin examination shows a nontender, necrotic ulcer with an erythematous rim and yellow-green, purulent exudate on the right thigh. There is another lesion with a hemorrhagic dark-bluish bulla and surrounding erythematous, indurated skin. Leukocyte count is 800/mm³ with 10% neutrophils.
Which of the following is the most likely cause of this patient's skin lesions?

Question

Quizplus · Accepted Answer

Explanation: This patient with a central venous catheter and chemotherapy-induced neutropenia developed rapidly progressive, ulcerative skin lesions, suggesting ecthyma gangrenosum. Ecthyma gangrenosum can be due to a number of different pathogens but is most commonly associated with Pseudomonas aeruginosa bacteremia in patients with immunocompromise (eg, neutropenia, immunosuppressant medications). Bacteria invade the perivascular structures (media, adventitia) of veins or arteries and induce secondary ischemic necrosis of the overlying tissue. This manifests with painless, red macules that rapidly progress to pustules/bullae and then quickly evolve into gangrenous ulcers with raised violaceous margins. The anogenital area, axilla, and extremities are most commonly affected, and single or multiple lesions may occur. Fever and signs of systemic illness are typically present. (Choice A) Clostridial myonecrosis, also called gas gangrene, is associated with fever, severe muscle pain, and purple-colored bullae. This patient does not have pain, making this condition unlikely. (Choice C) Patients with neutropenia and central venous access are at greater risk for invasive Candida infections. Skin lesions may occur but typically manifest as clusters of painless pustules on an erythematous base, sometimes with necrotic centers. This patient had a rapidly progressive bullous lesion that evolved into an ulcer, suggesting ecthyma gangrenosum. (Choice D) Mycosis fungoides is a cutaneous T-cell lymphoma that typically causes slowly (not rapidly) progressive skin lesions that appear as patches, plaques, tumors, or erythroderma. (Choice E) Pyoderma gangrenosum is a neutrophilic dermatosis that is usually associated with inflammatory bowel disease or an arthritides. Lesions typically begin as inflammatory nodules, pustules, or vesicles and quickly evolve to ulcers; however, they are usually quite painful. Educational objective: Ecthyma gangrenosum is most commonly seen in immunocompromised patients with Pseudomonas aeruginosa bacteremia. Manifestations typically include the rapid evolution of >1 skin lesion from an erythematous macule to a pustule or bullae and then into a nonpainful gangrenous ulcer. Fever and systemic signs of illness are common.

A 52-Year-Old Woman Is Brought to the Emergency Department Due