FDG Uptake by Brown Adipose Tissue in Paediatric and Adolescent Hodgkin Lymphoma, Visualised on PET/CT Performed at Diagnosis

We aimed to shed some light on the relation between brown adipose tissue (BAT) visualisation on FDG PET/CT at diagnosis in children with Hodgkin lymphoma (HL) and the main determinants reported in adult HL, outside temperature, gender, age, but also with the metabolic activity of HL lesions and of some organs that did not look to be invaded by HL. Pre therapeutic FDG PET/CT was performed in 135 children or adolescents suffering from HL and was centrally blind read, in search for BAT visualisation, determination of SUVmax of the liver, the bone marrow at the iliac crest and the spinal cord at Th12, providing those sites did not show focal uptake evocative of HL. The maximum SUVmax, total metabolic tumour volume, and total lesion glycolysis of HL were also determined. The visualisation of BAT as foci of FDG uptake in those patients with paediatric HL was not significantly associated with gender, age, the outside temperature on the day of PET/CT, the intensity of FDG in non-invaded organs and maximum SUVmax of HL tumours. There was a trend for an association with lower tumour volume and lower total lesion glycolysis of HL that did not reach the statistical significance level. Our study confirms, in 135 paediatric HL patients at diagnosis, i.e. a homogeneous clinical status, previous evidence derived from heterogeneous conditions, that the epidemiology of BAT activation is quite different between paediatric patients and adults. In relation to HL, BAT activation was not linked with the metabolic activation of the liver, the bone marrow, and the spinal cord, which may be observed as a consequence of HL presence in the patient. Nevertheless, our results suggest that BAT visualisation could be associated with a lower HL tumour mass.