(1) an infection of immunocompromised patients by a newly recognized bacterium, Bartonella henselae, characterized by fever, granulomatous cutaneous nodules, and peliosis hepatis in some cases. Skin biopsy shows vascular proliferation and infiltration of vessel walls by neutrophils and clumps of organisms seen with Warthin-Starry silver staining. (2) infectious disease characterized by fever and granulomatous cutaneous lesions. There are two forms. In one, associated with Bartonella henselae, cat bites and scratches are predisposing; lymph nodes and viscera may be involved, and bacillary peliosis of liver and spleen can occur. A separate form, associated with B. quintana, is linked with conditions of poor hygiene (louse infestation, poverty, poor or no housing); subcutaneous and bone lesions are more predominant.