Lymphoblastic lymphoma (LBL) is an uncommon neoplasm that accounts for about 5% of all non-Hodgkin's lymphomas. Approximately 90% of LBLs are of immature T-cell lineage, with B-cell lymphoblastic lymphoma (B-LBL) accounting for only about 10%. Owing to infrequency, the clinicopathological features and the imaging findings of B-LBL are not well defined. LBLs frequently affect extranodal sites. The most common site is the skin, followed by the bone, and the head and neck region is rarely involved. We report herein a case of childhood B-LBL occurring in the mental region, with emphasis on the findings of several imaging studies, including contrast-enhanced CT, MRI and fluorodeoxyglucose-positron emission tomography/CT.