LEARNING OBJECTIVES: 1) Recognize an atypical presentation of lymphoma 2) Recognize that systemic non-Hodgkin's lymphoma is a common HIV-related malignancy CASE INFORMATION: A 33 year old healthy male with no significant past medical history presented with three weeks of bilateral flank pain. His flank pain was intermittent but had progressively worsened, with radiation to his groin. The pain was associated with movement. He denied fevers/chills, nausea/vomiting, dysuria, or hematuria. Social history was negative for tobacco, alcohol, or illicit drugs. He was homosexual and involved in a long-term monogamous relationship. He had a family history of nephrolithiasis. On initial exam, he was afebrile with a benign abdominal exam, no costovertebral angle tenderness, a normal rectal exam, and guiac negative stool. A urinalysis was significant for +++blood and no leukocyte esterase or protein.