Kaposi sarcoma vs Bacillary angiomatosis
How to tell Kaposi sarcoma and Bacillary angiomatosis apart when a board question makes them look alike.
Kaposi is HHV-8 spindle-cell vascular tumor; bacillary angiomatosis is Bartonella vascular infection with silver-staining organisms.
Side by side
Kaposi sarcoma causes violaceous plaques or nodules from HHV-8 vascular tumor, especially in immunosuppression, with spindle cells and slit-like vascular spaces.
Bacillary angiomatosis causes red-purple vascular papules or nodules from Bartonella infection in immunocompromised patients and can mimic Kaposi but is infectious and antibiotic-responsive.
HHV-8 drives endothelial spindle-cell proliferation and angiogenic tumor formation.
Bartonella henselae or quintana infects endothelial tissue, causing vascular proliferation with neutrophils and organisms on silver stain.
HHV-8 positivity, spindle cells, slit-like spaces, and hemosiderin support Kaposi sarcoma.
Warthin-Starry silver stain, neutrophilic inflammation, cat or louse exposure, and antibiotic response support bacillary angiomatosis.
The trap
Both make purple vascular lesions in immunocompromised patients, so HHV-8 tumor histology versus Bartonella infection separates them.
The repair move
For vascular lesions in AIDS, separate viral tumor from Bartonella infection by histology and stain.
Try a free question
CoreA 34-year-old man with HIV, CD4 count 88 cells/uL, and a history of unprotected sex has 6 weeks of multiple violaceous patches and plaques on his face, trunk, and oral palate. Biopsy of a skin lesion shows spindle cells forming slit-like vascular spaces. Immunohistochemistry is positive for HHV-8 (LANA). Which diagnosis is most likely?
Show answer and explanation
Answer: A. Kaposi sarcoma. Kaposi sarcoma is HHV-8 (KSHV) driven vascular spindle-cell neoplasm, common in advanced HIV; histology shows slit-like vascular spaces with HHV-8 (LANA) positivity; treatment includes antiretroviral therapy for HIV-associated KS, with chemotherapy for extensive disease.
Why the other choices are tempting
- B. Bacillary angiomatosis is caused by Bartonella henselae/quintana in HIV; biopsy shows neutrophilic infiltrate with bacilli on Warthin-Starry silver stain.
- C. Hemangioma is a benign vascular tumor in infancy.
- D. Pyogenic granuloma is a friable bleeding vascular nodule from trauma.
- E. Melanoma has atypical melanocytes.
Flashcards
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What virus causes Kaposi sarcoma?
HHV-8 causes Kaposi sarcoma with violaceous vascular plaques and spindle-cell slit-like spaces.
What stain supports bacillary angiomatosis?
Warthin-Starry silver stain can show Bartonella in bacillary angiomatosis.
Quick answers
What is the fastest way to tell Kaposi sarcoma from Bacillary angiomatosis?
Kaposi is HHV-8 spindle-cell vascular tumor; bacillary angiomatosis is Bartonella vascular infection with silver-staining organisms.
What is the key clue for Kaposi sarcoma?
Kaposi sarcoma causes violaceous plaques or nodules from HHV-8 vascular tumor, especially in immunosuppression, with spindle cells and slit-like vascular spaces.
What is the key clue for Bacillary angiomatosis?
Bacillary angiomatosis causes red-purple vascular papules or nodules from Bartonella infection in immunocompromised patients and can mimic Kaposi but is infectious and antibiotic-responsive.
What is the common trap with Kaposi sarcoma vs Bacillary angiomatosis?
Both make purple vascular lesions in immunocompromised patients, so HHV-8 tumor histology versus Bartonella infection separates them.