Eight year old African girl with generalized adenopathy.
Multiple FDG-avid lymph nodes involving neck, axillae, mediastinum, retroperitoneum, iliac axis, inguinal regions, popliteal fossa and epitrochlear regions. Distribution is symmetrical. The majority of lymph nodes are smaller than 15 mm. Larger inguinal lymph nodes are found (20 mm). SUV max varies between 4 and 8. Spleen is mildly active but of normal size.
There was 32 million people living with HIV infection in 2011. HIV infects primarily CD4 T cells. When those cells decline, cell-mediated immunity is weakened and risk of opportunistic infections as well as malignancy increases.
Many studies have demonstrated that HIV viremia is associated with accelerated turnover lymphocytes. This turnover is thought to be the result of proliferation of both HIV-infected cells and uninfected cells. When activated, lymphocytes increase their glucose consumption 20-fold over a short period of time, using aerobic glycolysis.Peripheral generalized lymphadenopathies precede tissue involution and loss of superficial lymph nodes in later disease.
The use of FDG PET in HIV patients has been reported in several occasions.
Scharko et al. observed distinct lymphoid tissue activation in the head and neck during acute disease, a generalized pattern of peripheral lymph nodes activation at mid stage, and involvement of abdominal lymph nodes during late disease, suggesting that lymphoid tissues are engaged in a predictable sequence.
Brust et al. reported that healthy HIV-infected patients with suppressed viral loads and HIV negative individuals have no or little FDG nodal accumulation or any other hypermetabolic areas, whereas viremic individuals with early or advanced HIV had increased FDG in the peripheral nodes. Those findings suggest that FDG has the potential to identify areas of HIV replication.
Since HIV is associated with many infections and malignancies, FDG PET/CT interpretation needs a careful evaluation. Knowing the viral load is paramount. To avoid false positive findings, viral load should be suppressed during a malignancy assessment on FDG PET/CT.
Mhlanga et al. showed in another study that symmetry of nodal uptake appeared to be a valuable tool for differentiating lymphoma from reactive adenopathies in HIV-infected patients and has more discriminating power in aviremic patients.
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