A large congenital pancreatic cyst mimicking a macrocytic lymphatic malformation.

Congenital pancreatic cysts (CPCs) are rare developmental anomalies that arise in-utero from the pancreas. They are exceedingly rare in the literature, and most are discovered postnatally. Prenatal diagnosis is uncommon with only 21 published reports of prenatally diagnosed CPCs in the literature. CPCs may form unilocular or multilocular macrocysts which can distort normal anatomy. There is considerable overlap of imaging features with other macrocystic lesions of the neonatal abdomen. Ultrasound-guided biopsy and analysis of cyst aspirate for pancreatic enzymes may assist with obtaining an accurate preoperative diagnosis. We report a case of a 37-week gestational age female infant born with a known prenatal 9.5 cm macrocystic intrabdominal mass. An intrabdominal lymphatic malformation was initially diagnosed based on clinical and imaging features. Since conservative therapy with with cyst drainage and serial sclerotherapy was not effective, an ultrasound-guided biopsy was performed to rule out malignancy. Pancreatic tissue was identified on pathology. An exploratory laparotomy and total cystectomy was performed which confirmed the diagnosis of congenital pancreatic cyst originating from the pancreatic tail. This case highlights the diagnostic challenge of congenital pancreatic cysts and the importance of a multimodal and multidisciplinary diagnostic approach.