PET/CT in the evaluation of lymphoma in patients with HIV-1 with suppressed viral loads

OBJECTIVE: Positron emission tomography (PET) with F-18 fluorodeoxyglucose detects active lymphoid tissue during HIV-1 infection, with distinct patterns of lymphoid activation correlating to various stages of disease activity. Patients with HIV-1 are at risk for lymphoma, making the differential diagnosis between benign and malignant lymphadenopathy imperative. This study retrospectively evaluated the role of PET/computed tomography (CT) in differentiating active lymphoma from persistent generalized lymphadenopathy in patients with HIV-1. MATERIALS AND METHODS: Seven patients with HIV-1 underwent PET/CT. Six, with known non-Hodgkin lymphoma underwent a total of 16 PET/CT scans; 5/16 scans were performed for initial staging, and 10/16 for evaluating treatment response and follow-up. One patient was referred for evaluation of lymphadenopathy suspected of being lymphoma. PET/CT findings were compared with concurrent clinical, immunologic, and virological data. RESULTS: PET/CT accurately depicted the extent of lymphoma in 12/16 patients' scans (75%), yet in 4/16 (25%) scans increased fluorodeoxyglucose uptake was noted in lymph nodes of normal CT appearance (PET+/CT-). Viral loads ranged from 0 to 84,000 copies/mL, CD4 T-cell count ranged from 130 to 474 cells/μL in the group. The highest values of both laboratory parameters were concurrent with the discrepant PET+/CT- scans, seen in 4 scans, in 2 patients. The PET+/CT- findings in both these patients were observed in neck, axillae, mediastinum, spleen, and inguinal regions, and sample biopsies of the PET (+) nodes consequently proved benign findings in both patients. All PET+/CT+ findings correctly indicated lymphoma status, as proven by clinical follow-up. CONCLUSION: PET/CT accurately detected lymphoma in patients with HIV-1 and had been used confidently as a management tool in this patient group. In the context of discrepant PET/CT findings, increased viral loads and CD4 levels may imply benign HIV-related lymphadenopathy.