Poly-Infections in a Patient Living With Human Immunodeficiency Virus (HIV).

Febrile neutropenia (FN) is a medical emergency typically seen in immunocompromised patients with neutrophil counts below 500 cells/µL. It is often associated with chemotherapy, hematologic malignancy, and advanced human immunodeficiency virus (HIV) infection. Severe neutropenia in a low-level viremia and preserved CD4 T-helper cell (CD4) is uncommon and warrants evaluation for alternative etiologies. A 68-year-old man with HIV presented with fever and an absolute neutrophil count (ANC) of zero, without recent chemotherapy or other known myelosuppressive medications. Gram-negative bacteremia was identified, which is often attributed to gut translocation in neutropenic patients. Despite early initiation of tbo-filgrastim, the neutrophil count failed to respond; thus, a bone marrow biopsy was done to evaluate for an underlying marrow disorder. Bone marrow examination combined with genetic and molecular testing revealed a diagnosis of T-cell large granular lymphocytic leukemia (T-LGL), which explained the lack of response to tbo-filgrastim. Because the patient presented with profound neutropenia, gram-negative bacteremia, and a concern of hematologic malignancy, Strongyloides serology was ordered even without known travel or residence in endemic areas, and the result was positive. HTLV-1 serology was also obtained due to its known association with Strongyloides and gram-negative bacteremia, but it returned negative. This case emphasizes the need to broaden the differential diagnosis for severe neutropenia beyond HIV-related marrow suppression. Undiagnosed T-LGL may present with gram-negative bacteremia and failure to respond to granulocyte colony-stimulating factor (G-CSF), and Strongyloides infection should be considered in immunocompromised patients who are being evaluated for occult malignancy, even without identifiable epidemiological risk factors. Early recognition of these conditions can guide timely evaluation and appropriate therapy in complex immunocompromised hosts.