Bacillary angiomatosis is a bacterial disease which affects mainly immunosuppressed patients. It may compromise any tissue, especially the skin, presenting papules, nodules or angiomatous tumors. We studied three young men with AIDS, all of them with 1-2 papules, nodules or subcutaneous tumors suggesting telangiectatic granuloma, sarcoma and lipoma. Microscopically, they were misdiagnosed as telangiectatic granuloma, Kaposi's sarcoma and "angioma with secondary inflammation". After reviewing the histopathology, we saw them to be composed by vessels with prominent endothelium and stroma rich in leukocytoclastic polymorphonuclears. Fibrinoid deposits were observed in the neighborhood of vessels as well as minute eosinophilic granular interstitial masses corresponding to Bartonella aggregates, criteria which answer to the diagnosis of bacillary angiomatosis with HE staining. The Warthin-Starry stain was not useful; using resin embedded tissue from paraffin-embedded material, bacterial clusters, both in semithin section stained with toluidine blue and in thin sections observed under the electron microscope, were clearly seen, confirming bacillary angiomatosis diagnosis. Patients were successfully treated with surgery and either erythromycin or doxycycline. We reviewed the entity as well as its differential diagnoses with telangiectatic granuloma, Kaposi's sarcoma, Carrión's disease, and cat-scratch disease. In conclusion, we showed the presence of bacillary angiomatosis in three patients, illustrated its typical histopathological appearance with HE staining and demonstrated the causal bacteria in thick sections and with the electron microscope. It is essential to recognize bacillary angiomatosis, as it can be cured with antibiotics.