Malignant pustule

Malignant Pustule Malignant pustule is a cutaneous form of anthrax, a serious infectious disease caused by the bacterium *Bacillus anthracis*. This condition is characterized by a distinctive skin lesion that progresses through several stages, ultimately forming a black necrotic ulcer. It is important to understand the pathophysiology, clinical presentation, diagnosis, and treatment of malignant pustule to effectively manage and prevent this disease.

Pathophysiology

Malignant pustule occurs when *Bacillus anthracis* spores enter the skin through a cut or abrasion. The spores germinate and multiply, releasing toxins that cause local tissue damage and systemic effects. The primary toxin involved is the anthrax toxin, which consists of three proteins: protective antigen, lethal factor, and edema factor. These toxins disrupt cellular processes, leading to cell death and tissue necrosis.

Clinical Presentation

The initial presentation of a malignant pustule is a small, painless papule that resembles an insect bite. Within 1-2 days, the papule enlarges and develops a central vesicle or blister. This vesicle ruptures, forming a painless ulcer with a characteristic black necrotic eschar (scab) surrounded by edema and erythema. The lesion is often accompanied by regional lymphadenopathy and systemic symptoms such as fever and malaise.

Diagnosis

Diagnosis of malignant pustule is primarily clinical, based on the characteristic appearance of the lesion and the patient's history of exposure to anthrax. Laboratory confirmation can be obtained through:

• Culture and Isolation: *Bacillus anthracis* can be cultured from the lesion or blood.
• Polymerase Chain Reaction (PCR): PCR can detect anthrax DNA in clinical specimens.
• Serology: Detection of antibodies against anthrax toxins can support the diagnosis.

Treatment

Early treatment is crucial to prevent systemic spread and complications. The mainstay of treatment is antibiotic therapy. Recommended antibiotics include:

• Ciprofloxacin
• Doxycycline

In severe cases, combination therapy with additional antibiotics such as rifampin or clindamycin may be used. Supportive care and surgical debridement of necrotic tissue may also be necessary.

Prevention

Preventive measures include vaccination for individuals at high risk of exposure, such as military personnel and laboratory workers. Post-exposure prophylaxis with antibiotics is recommended for those exposed to anthrax spores.

Epidemiology

Malignant pustule is rare in developed countries but can occur in areas where anthrax is endemic, particularly in agricultural regions where livestock are not vaccinated against anthrax.

See Also

• Anthrax
• Cutaneous Anthrax
• Bacillus anthracis
• Centers for Disease Control and Prevention (CDC) guidelines on anthrax.
• World Health Organization (WHO) anthrax fact sheets.

External Links

• [CDC Anthrax Information](https://www.cdc.gov/anthrax/index.html)
• [WHO Anthrax Fact Sheet](https://www.who.int/news-room/fact-sheets/detail/anthrax)

NIH genetic and rare disease info

• NIH info on Malignant pustule

Malignant pustule is a rare disease.