‘Malignant pustule’ is
**Core Concept**
A malignant pustule is a characteristic skin lesion associated with cutaneous anthrax, caused by the bacterium *Bacillus anthracis*. This lesion represents a localized infection with subsequent necrosis and sloughing of the skin.
**Why the Correct Answer is Right**
The development of a malignant pustule is due to the bacterium's ability to produce a toxin that causes necrotic lesions. The skin lesion is initially a papule that progresses to a painless, ulcerative lesion with a characteristic black eschar in the center. This is a result of the bacterium's toxin-mediated damage to the skin tissue. The lesion is typically accompanied by regional lymphadenopathy and systemic symptoms such as fever and fatigue.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not describe the characteristic skin lesion associated with cutaneous anthrax.
**Option B:** This option is incorrect because it does not accurately describe the pathophysiology of a malignant pustule.
**Option C:** This option is incorrect because it does not specify the bacterium responsible for the lesion.
**Clinical Pearl / High-Yield Fact**
The term "malignant pustule" was coined because of the potentially deadly nature of the disease, but the lesion itself is not necessarily malignant in the classical sense. It is a serious sign that requires prompt medical attention.
**Correct Answer: D. Cutaneous anthrax, characterized by a painless, ulcerative lesion with a black eschar in the center.**