Neonatal appendicitis presenting as a painless abdominal mass

Cystic neuroblastoma, characterized by large cystic lesions typically originating from the adrenal gland, is a rare entity often diagnosed in the perinatal period. The majority of cases are localized, and complete surgical resection is curative in these cases. We present the case of a 3-week-old male infant who on imaging was found to have a cystic right suprarenal mass that was concerning for cystic neuroblastoma. At exploration, it was determined that this mass was a right upper quadrant abscess secondary to perforated appendicitis. Two years after his operation, the patient is doing well with no long-term complications.