An infection with Bartonella henselae transmitted from domestic cats to humans by scratching normally leads to cat-scratch disease. When the human host has severe immunosuppression or HIV infection, the potentially life-threatening disease bacillary angiomatosis can develop. A 79-year-old man presented with livid-erythematous, angioma-like skin lesions. We considered a cutaneous infiltrate from his known chronic lymphocytic leukemia, Merkel cell carcinoma, cutaneous metastases of internal tumors, cutaneous sarcoidosis, mycobacterial infection and even atypical herpes simplex infection. The correct diagnosis was proven histologically and by PCR. Because of increasing numbers of immunosuppressed and HIV-positive patients, as well as an infection rate of 13% for B. henselae in domestic cats in Germany, one must be alert to the presence of bacillary angiomatosis.