P020 A case of bacillary angiomatosis clinically mimicking Kaposi sarcoma

Abstract

A 53-year-old man with advanced HIV presented with a 2-year history of intermittent fevers, increasing fatigue, weight loss and noncompliance with antiretroviral therapy. He was previously treated for Kaposi sarcoma of the throat. On admission he was pancytopenic, with a CD4 count of 0.01 × 10⁹ cells L−1 and an HIV viral load of 4 million copies mL−1. Extensive investigations for pyrexia of unknown origin did not yield a diagnosis, including computed tomography of the chest, abdomen and pelvis; magnetic resonance imaging of the head; gastroscopy; colonoscopy; cerebrospinal fluid sampling; bone marrow biopsy; cryptococcal antigen; mycobacterial and routine cultures; and a screen for chronic viral infections. Despite broad-spectrum antibiotics, fevers persisted. The only clinical finding was a 2-cm violaceous ulcerated plaque above the left medial malleolus with ipsilateral inguinal lymphadenopathy. Differentials included Kaposi sarcoma and rare infections. A 4-mm punch biopsy demonstrated lobulated dermal vascular proliferation with neutrophilic and chronic inflammation with granulomatous change, including granular histiocytes, raising the possibility of bacillary angiomatosis. Microbiology stains, including silver stain, were negative. On further enquiry, the patient reported keeping three cats. Polymerase chain reaction from blood and the skin lesion were positive for Bartonella. The symptoms resolved following initiation of doxycycline and resumption of antiretroviral therapy. Typically, bacillary angiomatosis often presents with multiple nodules, usually on the upper limbs, and lymphadenopathy is uncommon. It can arise in immunocompromised patients, including those without HIV, or at sites of trauma in immunocompetent individuals, with transmission commonly occurring via cat scratch. This case highlights the need for clinical suspicion of bacillary angiomatosis, even with a solitary lesion mimicking Kaposi sarcoma and negative staining for microorganisms.