An Unusual Skin Lesion in a Woman With Pseudomonas aeruginosa Bacteremia

A 77-year-old woman was admitted to the hospital from a nursing home with sepsis and hypotension. Her concurrent morbidities included chronic ventilator-dependent respiratory failure, diabetes mellitus, and hypoalbuminemia. Her hemodynamic status improved with fluid challenge and broad-spectrum antibiotics.

At admission, a chest radiograph showed ill-defined infiltrates in the left lung, while blood cultures were positive for Pseudomonas aeruginosa. Fifteen days after admission, a lesion appeared on the right forearm (Figure 1). The lesion first appeared as a dark red blister, which rapidly developed within 24 hours into an ulcer, with an inflamed margin and surrounding erythema. The base of the ulcer was necrotic with a dark eschar.

Biopsy and culture of the skin lesion was performed. Histopathology results showed ulceration and necrosis of the epidermis and dermis (Figure 2), necrotizing vasculitis (Figures 3 and 4), and gram-negative bacilli. Culture results of the skin tissue were negative, most likely as a result of the 2 weeks of antibiotic treatment prior to collection.

What is this woman’s necrotic, ulcerated lesion?

Min Qiao, MD, is a resident in the Department of Medicine at Kingsbrook Jewish Medical Center in Brooklyn, New York.

Shuhua Song, MD, is a resident in the Department of Medicine at Kingsbrook Jewish Medical Center.

Davinder Chandhoke, MD, is a staff pathologist in the Department of Pathology at Kingsbrook Jewish Medical Center.

Vincent Peyko, PharmD, BCPS, is a pharmacist and coordinator of infectious disease pharmacotherapy in the Department of Pharmacy at Kingsbrook Jewish Medical Center.

Orlando Carpio, MD, is an attending physician in the Department of Medicine at Kingsbrook Jewish Medical Center.

Rajat Mukherji, MD, is chief of pulmonology in the Department of Medicine at Kingsbrook Jewish Medical Center.

Answer: Ecthyma Gangrenosum

A 77-year-old woman was admitted to the hospital from a nursing home with sepsis and hypotension. Her concurrent morbidities included chronic ventilator-dependent respiratory failure, diabetes mellitus, and hypoalbuminemia. Her hemodynamic status improved with fluid challenge and broad-spectrum antibiotics.

At admission, a chest radiograph showed ill-defined infiltrates in the left lung, while blood cultures were positive for Pseudomonas aeruginosa. Fifteen days after admission, a skin lesion appeared on the woman’s right forearm (Figure 1).

The lesion first appeared as a dark red blister, which rapidly developed within 24 hours into an ulcer, with an inflamed margin and surrounding erythema. The base of the ulcer was necrotic with a dark eschar.

Biopsy and culture of the skin lesion was performed. Histopathology results showed ulceration and necrosis of the epidermis and dermis (Figure 2), necrotizing vasculitis (Figures 3 and 4), and gram-negative bacilli. Culture results of the skin tissue were negative, most likely as a result of the 2 weeks of antibiotic treatment prior to collection.

These findings were consistent with a diagnosis of ecthyma gangrenosum (EG).

Discussion

EG is a skin lesion that usually is associated with systemic infection, although it occasionally can occur as a result of local inoculation of infective organisms. The hallmark of the lesion is small-vessel vasculitis, resulting from the invasion of vessels in the skin by infective organisms. The result is necrosis of the vessel walls from vascular occlusion, with a consequent necrotic ulceration of the skin.

The lesion usually starts as a hemorrhagic pustule or blister, which breaks down into an ulcer. The base of the ulcer frequently is covered with a dark scab, while the margin and surrounding skin demonstrate erythema and edema.

Organisms causing EG range from bacteria (such as Staphylococcus aureus,¹ Escherichia coli,² Citrobacter freundii,³ Klebsiella pneumoniae,⁴ Morganella morganii⁵) to fungi (such as Candida albicans,⁶ Mucor pusillus,⁷ and Fusarium solani⁸), and even viruses.⁹ The most common causative organism is P aeruginosa. In a retrospective review of published reports of EG,¹⁰ 123 of 167 (73.65%) cases over 39 years were caused by P aeruginosa; of these 123 cases, 72 (58.5%) had a positive blood culture for P aeruginosa. On occasion, tissue culture grew the organism.

EG is more likely to occur in immunosuppressed states such as malignancy, neutropenia, AIDS, malnutrition, and diabetes mellitus.

The skin lesion requires adequate treatment of the systemic infection with antibiotics. When the lesion remains refractory to medical management, surgical debridement may be called for.

Although its manifestations may resemble those of EG, pyoderma gangrenosum is not associated with infections and is painful and tender. Other necrotic skin conditions may occur with the use of warfarin, cocaine, or norepinephrine, none of which were found in our patient’s history.

Our patient received a total of 6 weeks of antibiotic treatment based on her blood culture and sensitivity report. Her fever subsided, her white blood cell count normalized, and subsequent blood cultures were negative. The skin lesion shrank but persisted, despite the patient’s overall clinical improvement. By the end of 6 weeks, surgical debridement was done, and the patient was discharged from the hospital. 

The author discusses the case in this podcast:

Min Qiao, MD, is a resident in the Department of Medicine at Kingsbrook Jewish Medical Center in Brooklyn, New York.

Shuhua Song, MD, is a resident in the Department of Medicine at Kingsbrook Jewish Medical Center.

Davinder Chandhoke, MD, is a staff pathologist in the Department of Pathology at Kingsbrook Jewish Medical Center.

Vincent Peyko, PharmD, BCPS, is a pharmacist and coordinator of infectious disease pharmacotherapy in the Department of Pharmacy at Kingsbrook Jewish Medical Center.

Orlando Carpio, MD, is an attending physician in the Department of Medicine at Kingsbrook Jewish Medical Center.

Rajat Mukherji, MD, is chief of pulmonology in the Department of Medicine at Kingsbrook Jewish Medical Center.

References:

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