CD4 and aneurysmal bone cyst: In a study from Trédan et al., the cohort of patients with aBC treated in first line showed a median OS of 1.2 months for severe CD4+ lymphopaenic patients, 14.7 months for patients with mild CD4+ lymphopaenia and 24.9 months for non-CD4+ lymphopaenic patients (log rank p-value < 10−4) (46).