CASE PRESENTATION: A 49 year old male with AIDS on antiretroviral therapy (CD4 113 cells/μL) presented with five days of progressively worsening diffuse abdominal pain, night sweats, generalized fatigue and malaise. Physical exam revealed enlarged and tender cervical, supraclavicular, axillary and inguinal lymph nodes. Labs revealed normocytic anemia and thrombocytopenia. Shortly after admission, he developed high-grade fevers (39-40 degree Celsius) and was started on broad-spectrum antibiotics. This was followed by a complete infectious workup. CT scan demonstrated hilar and mediastinal lymphadenopathy along with hepatosplenomegaly and diffuse lymphadenopathy throughout the abdomen and pelvis. An excisional supraclavicular node biopsy was performed on day three of hospitalization. Soon after, positive serologies for Bartonella Quintana (IgG 1:512, IgM negative) returned, and he was started on doxycycline for treatment of bacillary angiomatosis. Nine days into hospitalization, pathology revealed atypical interfollicular plasmacytosis with focal lamda light chain-restricted immunoblasts and HHV-8 positive cells, consistent with multicentric Castleman’s disease. Bartonella Quintana stains (Warthin-Starry and Bartonella immunohistochemistry) from the lymph node sample were negative. Doxycycline was discontinued and the patient was referred to oncology for follow-up with plans to start treatment with gancyclovir, rituximab and chemotherapy.