Thymic tissue is not evident on high-resolution computed tomography and [18F]Fluoro-deoxyglucose positron emission tomography scans of aviraemic HIV patients with poor recovery of CD4+ T cells

Some previously immunodeficient HIV patients responding to antiretroviral therapy display poor recovery of CD4(+) T cells. Evaluation of the contribution of thymic function requires sensitive detection and quantitation of metabolically active thymic tissue. We describe patients with low but detectable thymopoiesis assessed as circulating CD4(+) naive T cells expressing CD31. High-resolution computed tomography and PET scans found no residual thymic tissue even though metabolic activity was demonstrable by PET in lymph nodes.