Bacillary angiomatosis is a bacterial infection that causes lesions on your skin, liver, spleen, mucosal surfaces, and other organs. These lesions look similar to Kaposi sarcoma, and the two are often mistaken for each other.

It tends to only affect people with weakened immune systems. Keep reading to learn more about bacillary angiomatosis, including its symptoms and the available treatment options.

The main symptoms of bacillary angiomatosis are lesions on your skin. While they can occur anywhere, they’re most common on:

  • the inside of your mouth
  • the soles of your feet
  • the palms of your hand

The lesions tend to be firm, raised, and reddish in color. They’re also usually surrounded by an area of scaly skin. If you pick at them, you might notice that they bleed a lot.

Additional symptoms of bacillary angiomatosis can include:

Two types of bacteria can cause bacillary angiomatosis:

  • Bartonella henselae
  • Bartonella quintana

Both types originate in insects. B. henselae is spread by fleas that live on domestic cats. It’s the same bacteria that causes cat scratch fever. While bacillary angiomatosis is linked to interacting with cats, you can get it without exposure to a cat. B. quintana is spread by lice.

Most cases of bacillary angiomatosis affect people with weakened immune systems. Many things can affect your immune system, including:

However, people who don’t have weakened immune systems can still get bacillary angiomatosis. For example, some people develop it near the site of a severe burn or cat scratch.

To diagnose bacillary angiomatosis, your doctor will start by doing a basic physical exam and looking over your medical history. Make sure you tell your doctor about any underlying conditions you have that they might not know about.

Depending on your symptoms and history, they may do some testing, such as:

  • Biopsy of skin lesions. Your doctor will take a small sample of skin from one of the lesions and analyze it for signs of a bacterial infection.
  • Serology. This involves taking a sample of serum from a simple blood draw and checking it for antibodies to Bartonella bacteria.
  • Bacterial culture. Your doctor can isolate Bartonella bacteria from a blood sample. However, it can take about 5 to 15 days for the bacterial colonies to appear.
  • Molecular testing. If your doctor still isn’t sure what’s causing your symptoms, they can use a DNA-based method called a polymerase chain reaction to detect Bartonella DNA in a tissue sample.

Bacillary angiomatosis requires treatment with antibiotics. Erythromycin and doxycycline are both common antibiotics used to treat this condition.

Keep in mind that you’ll likely need to take these antibiotics for at least three months, though your symptoms should start to improve within three to four weeks.

If your symptoms haven’t improved after about a month, you may need to take antibiotics for a longer period of time.

In addition, your doctor might need to drain any large lesions or blisters that don’t go away on their own or cause discomfort.

If left untreated, bacillary angiomatosis can cause your blood vessels to grow. When this happens, masses can grow on your organs, such as your liver or spleen. At this point, bacillary angiomatosis becomes life-threatening.

You can reduce your risk of complications by contacting your doctor right away if you start to notice skin lesions, especially if you have a weakened immune system.

Bacillary angiomatosis is a serious bacterial infection that can be fatal if not treated.

If you have a weakened immune system, keep an eye out for any unusual symptoms so you can start treatment early.

Most cases respond well to taking antibiotics for a few months, though you should start to notice an improvement in your symptoms within about a month.