Bacillary Angiomatosis vs Kaposi's Sarcoma: What Are The Differences?

In this article, we will review and compare bacillary angiomatosis and Kaposi's sarcoma, two conditions that can manifest with vascularised skin lesions in people with dysfunctional immune systems. We will review their causes, symptoms, and treatment options, highlighting the key differences between these two medical conditions.
Jakub Hantabal

Jakub Hantabal

Postgraduate student of Precision Cancer Medicine at the University of Oxford, and a data scientist.

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What is Bacillary Angiomatosis?

Bacillary angiomatosis (BA) is a bacterial infection that primarily affects people with dysfunctional immune systems (immunocompromised) - such as those with HIV or some types of cancer. The disease is caused by the bacteria Bartonella henselae and Bartonella quintana.

Symptoms of Bacillary Angiomatosis

The primary presentation of BA is the appearance of multiple red (erythematous) vasoproliferative nodules on the skin. They are essentially growths of blood vessels.

These growths primarily occur on the skin, but can be also present in other parts of the body and organs, including soft tissues, bones, lymph nodes, liver and spleen.

Other symptoms can be non-specific, including a persistent fever, abdominal pain, swelling of the lymph nodes and night sweats. Additionally, pleural effusions (presence of fluid around the lungs) can occur, and if the lesions are present on the spleen may result in peliosis, which means presence of blood-filled cysts in the liver.

Diagnosis of Bacillary Angiomatosis

BA is diagnosed via a combination of clinical examination, histology, and blood testing. A biopsy of the nodule is usually taken, especially if the lesion presents on the skin. This is a simple procedure, where the area is numbed with local anaesthetic, and a part of the lesion, or the whole lesion is cut away and sent for histological analysis.

During the histological analysis, the tissue is cut into very thin pieces, stained with specialised dyes that allow for visualisation of certain molecules and features, and examined under the microscope.

The histological findings for the diagnosis of BA include a proliferation (growth) of blood vessels in the lesion, infiltrate of neutrophils (immune cells that fight bacterial infections), and presence of ampophilic (reacts to both acidic and basic stains) plaques - these are formed by aggregated bacilli.

Bacilli are types of rod-shaped bacteria, and these include the causative agents of BA. To confirm the presence of the bacilli a stain called Warthin-Starry stain is used.

If blood is taken, cultures are set up to confirm bacteremia - the presence of bacteria in blood. This involves taking blood and incubating it with or without air (aerobic or anaerobic) and observed under a microscope for presence of growing bacteria [1, 2, 3, 4, 5].

Treatment for Bacillary Angiomatosis

As bacillary angiomatosis is a bacterial infection, antibiotics are the gold standard of treatment. The first-line therapeutic is erythromycin, taken as a tablet four times daily for 2 weeks to a month. Other antibiotics, including doxycycline, azithromycin, and clarithromycin can also be considered.

The choice of the antibiotic depends on the severity of the infection, as well as the patient's health, and potential resistance of the growing bacteria to some types of antibiotic.

What is Kaposi Sarcoma?

Kaposi sarcoma (KS) is a subtype of sarcoma, a type of cancer that arises from the connective tissues of the body.

Kaposi Sarcoma develops by a malignant transformation (cell mutating and turning cancerous) of the cells that form the internal lining of the blood vessels.

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Jakub Hantabal

Jakub Hantabal

Jakub is a postgraduate student of Precision Cancer Medicine at the University of Oxford, and a data scientist. His research focuses on the impact of hypoxia on genetic and proteomic changes in cancer. Jakub also consults and collaborates with multiple institutions in the United Kingdom and Slovakia supporting research groups with advanced data analysis, and he also co-founded an NGO organising educational events in data science.