Renal medullary carcinoma (RMC) is an aggressive neoplasm occurring almost exclusively in adolescents and young adults with sickle cell (SC) hemoglobinopathies, usually sickle cell trait (SCT) or hemoglobin SC disease. The most common presentations are hematuria and flank or abdominal pain. It is a highly malignant tumor, and responses to chemotherapy are rare and transient resulting in a dismal prognosis. A high level of suspicion is necessary when evaluating at risk patients presenting with hematuria or flank pain, as currently it appears that only early diagnosis could potentially alter the outcome of this disease. We report a case of RMC in a young male patient with SCT, who presented to the emergency department with low back pain and microscopic hematuria, clinically mimicking acute obstructing urolithiasis. Our case emphasizes the need to consider alternate diagnoses when evaluating computed tomography scans for acute flank pain.