A 7-year-old boy presented with increasing abdominal girth and abdominal pain. Abdominal ultrasound revealed a pleural effusion and ascites. Computed tomography (CT) demonstrated a mass involving the peritoneum, mesentery, and omentum with marked ascites, mesenteric nodules, and renal involvement. Positron emission tomography (PET)/CT scan identified additional tumor within the pleura. PET/CT imaging was helpful in identifying the appropriate pleural mass biopsy site in this patient with Burkitt lymphoma.