At the present time Hodgkin lymphoma (HL) can be cured in more than 80 % of all patients [1]. Over 90 % of patients with early-stage HL are cured with contemporary combinedmodality therapy, but there are still 25 -30 % of patients with advanced-stage disease who are not cured with the ABVD regimen alone [1,2]. The International Prognostic Score (IPS) fails to recognize these patients with a high risk of treatment failure since the range of outcomes it delineates has narrowed with treatment improvement [1]. Although clinical prognostic scores continue to be routinely used, the need to identify patients with poorer risk has focused research on the tumoral microenvironment to find valuable prognostic information. Indeed, the tumour tissue in HL is composed of a few scattered neoplastic cells called Hodgkin and ReedSternberg (HRS) cells, which account for less than 1 % of all the cells found in biopsy specimens, that are surrounded by an overwhelming population of nonneoplastic mononuclear bystander cells. These cells (CCR4-expressing cell subsets, including eosinophils, histiocytes, macrophages, plasma cells, and Th2 and Treg lymphocytes) are recruited by chemokines produced by the HRS cells and induce the expression of antiapoptotic proteins in HRS cells and their immortalization via a paracrine loop [3,4]. There is an intimate relationship between the HRS cells and reactive cells of the microenvironment that enables the tumour to thrive and evade immune surveillance. Some recent studies have suggested a prognostic role for the nonneoplastic surrounding cells.In classic HL (CHL) tumour-associated macrophages (TAMs) have been shown to be associated with inferior outcomes [5]. Steidl et al. showed that a macrophage gene expression signature is associated with primary treatment failure in CHL and subsequently showed, using an independent validation cohort, that an increase in CD68-positive macrophages in the microenvironment is associated with inferior outcomes [5]. In the E2496 Intergroup trial, a multicentre phase 3 randomized controlled trial comparing ABVD and Stanford V chemotherapy in 287 patients with locally extensive and advanced stage CHL, increased CD68 or CD163 expression was significantly associated with inferior 5-year failure-free survival (FFS; 64 % vs. 78 % and 63 % vs. 82 %) and 5-year overall survival (OS; 81 % vs. 94 % and 81 % vs. 96 %). Multivariate analysis with clinical and biological factors linked to FFS (lymphocyte count, stage 4 disease) and OS (age ≥45 years) showed that increased CD68 or CD163 expression are significant independent predictors of inferior FFS and OS [6]. However, prognostic indices using these results in routine have not yet been built.HL is a lymphoma showing FDG avidity with 100 % of patients positive at baseline, and FDG PET is currently the most accurate staging modality [7]. It has been shown that different mechanisms of glucose uptake, e.g. via GLUT1 in HRS cells and via GLUT3 in the microenvironment, contribute to PET positivity of the tumour [8]. In a recent study...