FDG-PET for Staging and Follow-up of HIV-Infected Patients with Non Hodgkin Lymphoma and Hodgkin Lymphoma: A Single Center Experience.

Risk of developing non Hodgkin lymphomas (NHL) is known to be increased among patients (pts) infected by HIV-1 and sporadic non-HIV related cases of Hodgking lymphomas (HL) are also described. HIV-positive pts also feature a virus-related systemic lymphoadenopathy which makes nodal involvement by lymphoma difficult to evaluate using conventional imaging. The role of positron-emission tomography using ¹⁸F-fluorodeoxyglucose (FDG-PET) in the staging and evaluation of response to treatment of pts with NHL and HL is well established in immunocompetent pts, while only limited information is available on lymphomas arising in the setting of HIV infection. We report on a retrospective analysis of FDG-PET results in a group of HIV pts with lymphoma, both NHL and HL, followed-up at our hospital.

Twelve HIV-positive male pts with a diagnosis of lymphoma (7 high grade and 1 follicular NHL, 4 HL) underwent a total of 22 PET scans. PET results were compared with those obtained by computed tomography (CT). Nine PET were performed at staging, 7 at restaging following chemotherapy, and 6 at follow-up. At diagnosis of lymphoma: median CD4 count was 200 cells/mcL (range 98-451); HIV genome was undetectable in 5/9 pts, in the remaining 4 pts for whom the data was available viral loads ranged from 103 to 1,452,720 copies/mL; 10/12 pts were already receiving HAART, while the remaining 2 pts started treatment upon diagnosis of lymphoma.

In the majority of cases (17/22 = 77%) results of PET, CT scan and clinical status were concordant, being diagnostic of either lymphoma presence (11/17) or absence (6/17). No false positive results were recorded at follow-up. In 5/22 cases (23%) PET and CT scan were discordant. In 4 cases PET yielded a false negative result; in 2 cases at diagnosis (2 pts with HL) and in 2 cases at follow-up (both in the pt with follicular lymphoma). In the remaining case, a PET-negative CT-positive adenopathy was demonstrated which proved to be reactive in nature at biopsy.

Our results suggest that FDG-PET is useful in the evaluation of lymphoma in the setting of HIV infection, similarly to what has been observed among immunocompetent pts. Although the number of patients is limited, in our experience PET proved to be able to discriminate between reactive and lymphomatous involvement of lymphoid tissue as demonstrated by absence of false positive results in pts evaluated at follow-up. These results need to be confirmed by larger clinical trials.

No relevant conflicts of interest to declare.