Precursor B-cell lymphoblastic lymphoma (PBLL) is a rare subtype of non-Hodgkin lymphoma originating from B-cell precursors. PBLL, as a solitary mass lesion affecting the central nervous system without leukemic disease at presentation, is quite uncommon. Here we report a rare PBLL case with Philadelphia chromosome positivity. The 44-year-old male presented a solitary bulky mass primarily involving the left frontotemporal lobes and extended into the infratemporal fossa. Pretreatment PET/CT imaging showed avid 18F-fluorodeoxyglucose (18F-FDG) uptake of the lesion. By aggressive chemotherapy and imatinib maintenance treatment, the patient achieved and remained in complete remission on another two consecutive PET/CT imaging follow-ups.