Neuroblastoma associated with pyrexia of unknown origin: An unusual presentation

Neuroblastoma is the most common extracranial solid malignancy in children and may present with diverse clinical features. We report a case of a 4-month-old male infant who presented with pyrexia of unknown origin (PUO) and was found to have a retroperitoneal mass (84×74×88 mm) on imaging. Histopathological and immune-histochemical findings confirmed the diagnosis of neuroblastoma. The tumor was staged as 1/2A as per the International Neuroblastoma Risk Group Staging System (INRGSS), as per guideline close observation and follow up initiated. After that this case classified under intermediate risk disease and start neoadjuvant chemotherapy for 6 to 24 week. This case highlights the importance of considering neuroblastoma in the differential diagnosis of PUO in infants, even under 6 months of age.