Hypodense thymic lesions in Hodgkin Lymphoma

Abstract Hypodense volumes (HDV) in mediastinal thymic lesions can be visualized in a computed tomography scan in Hodgkin lymphoma. We analyzed staging CT scans of 1178 patients with mediastinal involvement from the EuroNet-PHL-C1 trial and explored correlations of HDV with patient characteristics, mediastinal tumor volume and progression-free survival. HDV occurred in 350 of 1178 patients (29.7%), typically in larger mediastinal volumes. There were different patterns in appearance with single lesions found in 243 patients (69.4%), multiple lesions in 107 patients (30.6%). Well delineated lesions were found in 248 cases (70.1%), diffuse lesions were seen in 102 cases (29.1%). Clinically, B symptoms occurred more often in patients with HDV (47.7% compared to 35.0% without HDV (p=0.039)) and patients with HDV tended to be in higher risk groups. Inadequate overall early- 18 F-FDG-PET-response was strongly correlated with the occurrence of hypodense lesions (p<0.001). Patients with total HDV > 40ml (n=80) had a 5-year PFS of 79.6% compared to 89.7% (p=0.01) in patients with HDV < 40ml or no HDV. This difference in PFS is not caused by treatment group alone. HDV is a common phenomenon in HL with mediastinal involvement Further research should be considered for validation as an independent prognostic factor for PFS.