402 Persistent Thrombocytosis in a Child Leading to the Detection of Fibrolamellar Hepatocellular Carcinoma

Introduction/Objective In pediatric patients, thrombocytosis is commonly a reactive process associated with iron deficiency, infection, or inflammation. However, persistent elevation of platelet counts despite appropriate treatment warrants further investigation. This case illustrates how ongoing abnormalities in laboratory findings can uncover a rare malignancy, highlighting the crucial role of laboratory evidence in early diagnosis and guiding clinical management. Methods/Case Report A 12-year-old boy presented with a three to four-month history of persistent vomiting, frequent loose stools, and fatigue. Initial laboratory evaluation revealed severe anemia with hemoglobin of 4.3 g/dL, a low mean corpuscular volume (MCV) of 72 fL, and marked thrombocytosis with a platelet count of 878 × 109/L. Iron deficiency anemia was confirmed, while fecal elastase and tissue transglutaminase antibody tests were negative, excluding common malabsorption syndromes. Despite treatment with blood transfusion and iron supplementation resulting in improved hemoglobin and reticulocyte counts, the patient’s platelet count remained elevated. Routine complete blood count follow-up was advised. Shortly thereafter, the patient developed jaundice. Liver function tests demonstrated elevated enzymes, and viral hepatitis serologies for hepatitis A, B, and C were negative. Abdominal ultrasound revealed a mass in the right hepatic lobe. Tumor markers alpha-fetoprotein (AFP) and CA 19-9 were within normal limits, whereas CA-125 was elevated. Computed tomography (CT) imaging confirmed features consistent with fibrolamellar hepatocellular carcinoma. Results N/A Conclusion Persistent thrombocytosis in pediatric patients, especially when unresponsive to treatment, should prompt thorough evaluation to exclude serious underlying conditions. This case underscores the importance of integrating laboratory findings with clinical follow-up to facilitate early diagnosis and appropriate management.