Bacillary angiomatosis

Last updated: September 16, 2021

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Bacillary angiomatosis is a skin condition in immunocompromised patients (especially patients with AIDS and/or CD4 count < 100) characterized by vascular proliferation that results in lesions on the skin and potentially other organs (e.g., GI tract, respiratory tract). It is caused primarily by Bartonella henselae, which is most commonly transmitted via cat scratches. Skin manifestations include red papules and nodules that bleed easily. Diagnosis is confirmed on biopsy. Antibiotics are used to treat bacillary angiomatosis, and patients with HIV should be started on ART.

  • Biopsy of lesion (first-line test) [1]
  • The following studies may provide supportive evidence but are not widely available/used: [1]
    • Serology (may be negative in up to 25% of patients with HIV)
    • Blood or tissue culture for isolation Bartonella (may be negative even in affected patients)
    • PCR of tissue samples

Serology may be unreliable in advanced HIV infection, as some patients never develop antibodies!

Neutrophilic inflammation is seen in bacillary angiomatosis. Lymphocytic inflammation is seen in Kaposi sarcoma.

The differential diagnoses listed here are not exhaustive.

  • Bartonella henselae [1]
    • Limit cat ownership to cats > 1 year old and in good condition; provide regular flea treatment.
    • Reduce the risk of cat scratches: Avoid petting stray cats and playing roughly with cats.
    • Clean any scratches promptly with soap and clean water.
  • Bartonella quintana [1]
    • Advise patients to avoid sharing clothes or bedding; wash clothes and bedding in hot water (> 50°C/120°F).
    • Provide treatment to patients affected by body lice.
  1. Guidelines for the Prevention and Treatment of Opportunistic Infections in Adults and Adolescents with HIV. Updated: August 18, 2020. Accessed: December 18, 2020.

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