Burkitt-like variant of HGBL, NOS. (A) High magnification of hematoxylin and eosin stain shows a starry-sky pattern with a diffuse infiltrate of medium to large cells with finely dispersed chromatin, several small nucleoli, and frequent mitoses. (B) Malignant B cells express the germinal center markers CD10 and BCL6 but are largely negative for BCL2. (C) Ki-67 proliferation index was ∼100%, and neoplastic cells showed high expression of MYC but were CD43⁻; other negative markers included BCL1, TdT, MUM1, and EBER by in situ hybridization. (D) FISH shows no evidence of MYC-R or BCL2-IGH rearrangement (FISH probes: Vysis LSI IGH/MYC/CEP 8 Tri-Color Dual Fusion Probe, Vysis LSI MYC-Dual Color Break-Apart Probe, and Vysis LSI IGH/BCL2 Dual Color Dual Fusion Probe; Abbott Molecular). (E) Cerebrospinal fluid cytology shows medium to large cells with round to irregular nuclear contours, variably prominent nucleoli, and moderate amount of cytoplasm. (F) The patient, a 43-year-old HIV⁻ man, presented with extensive abdominal adenopathy and infiltration of the CNS, gastrointestinal tract, bilateral kidneys, and adrenal glands on computed tomography scan; he attained a complete response (CR) to the R-CODOX-M/IVAC (rituximab plus cyclophosphamide, doxorubicin, vincristine, and high-dose methotrexate alternating with ifosfamide, cytarabine, and etoposide) regimen with intrathecal therapy and remains in remission 1 year later. Original magnification: ×600 (A), ×400 (B-C), and ×1000 (E).