Case History: The patient was HIV+ adult male who presented with aches and pains in the inguinal region. An abdominal CT showed a 10 cm pelvic mass abutting his prostate and colon. A transrectal ultrasound-guided biopsy was done. Sections showed diffuse sheets of high-grade neoplastic cells with large vesicular nuclei, prominent nucleoli, and brisk mitotic activity (see higher magnification in the next image). An initial immunohistochemical panel consisting of CD45, CD20, CD79a, CD30, ALK-1, bcl-1, S-100 protein, HMB-45, cytokeratin AE1/AE3, EMA, and myeloperoxidase was negative. CD3 and CD5 showed scattered lymphocytes in the background. A subsequent panel showed strong positivity for CD38 and CD138 and focal weak positivity for lambda light chains. The final diagnosis was plasmablastic lymphoma.