Bacillary angiomatosis is caused by:
**Core Concept**
Bacillary angiomatosis is a rare, acquired vascular disorder caused by infection with specific bacteria, leading to the formation of abnormal blood vessels and skin lesions. It predominantly affects immunocompromised individuals, such as those with HIV/AIDS.
**Why the Correct Answer is Right**
Bacillary angiomatosis is primarily caused by *Bartonella henselae* and, less commonly, *Bartonella quintana*. These bacteria induce angiogenesis, leading to the formation of vascular tumors and skin lesions. The infection occurs through the bite of an infected cat flea, which transmits the bacteria to humans. The bacteria interact with endothelial cells, promoting the expression of vascular endothelial growth factor (VEGF) and other angiogenic factors, resulting in the formation of abnormal blood vessels.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because *Bartonella bacilliformis* is primarily associated with Oroya fever and verruga peruana, which are distinct clinical entities from bacillary angiomatosis.
* **Option B:** This option is incorrect because *Bartonella elizabethae* is an opportunistic pathogen that can cause endocarditis and bacteremia, but it is not primarily associated with bacillary angiomatosis.
* **Option C:** This option is incorrect because *Bartonella vinsonii* is a zoonotic pathogen that can cause endocarditis and bacteremia, but it is not primarily associated with bacillary angiomatosis.
**Clinical Pearl / High-Yield Fact**
Bacillary angiomatosis should be suspected in immunocompromised patients presenting with skin lesions and a history of cat ownership or exposure to cat fleas.
**Correct Answer:** D. *Bartonella henselae*