P0901 - The Baby With a Big Belly: Life-threatening Abdominal Distention in a Newborn

Introduction: Abdominal distention in newborns can be a sign of a life-threatening condition. Timely examination and imaging studies are important to prevent adverse outcomes.

Case Description: A male infant was born at 35+5 weeks estimated gestational age via emergent Cesarean section for non-reassuring fetal heart tones. His mother had no prenatal care until 23 weeks estimated gestational age. Upon delivery he was limp and did not cry; Apgar scores were 3 and 8. On examination he was pale with a moderately distended abdomen, firm to palpation on the right side. He passed a meconium stool and his first void contained frank blood. An x-ray showed bowel gas only on the left side of his abdomen. An MRI showed a right renal mass measuring 6.7 by 7.1 by 8.8 cm. Within 24 hours of birth he developed lactic acidosis, anemia, and shock requiring an emergency laparotomy, which revealed blood in the abdomen and rupture of the renal mass. He underwent a right nephrectomy, and morphologic and immunohistochemistry findings from the mass were consistent with cellular mesoblastic nephroma. Ancillary cyto-molecular studies confirmed NTRK3-ETV6 fusion. Eight days later he developed abdominal distention; x-ray showed air-fluid levels and distended, fixed loops of bowel. He underwent an exploratory laparotomy which found a necrotic duodenum and perforated colon, requiring duodenal resection, gastrojejunostomy, right hemicolectomy with ileostomy, and Hartman’s pouch drain placement. Nuclear medicine bone scan 8 weeks later showed no metastases. At 9 weeks of life he began chemotherapy with vincristine and dactinomycin. He was discharged home at 13 weeks of life with planned delayed re-anastomosis of the bowel after completing chemotherapy.

Discussion: Congenital gastrointestinal malformations and renal tumors including fetal hamartoma, nephroblastoma, and congenital mesoblastic nephroma (CMN) are not uncommon in newborns, but it is rare for a newborn to present with a palpable abdominal mass, hematuria, and hemorrhagic shock. Pathologic evaluation of this patient’s resected kidney was consistent with cellular CMN, a type of infantile fibrosarcoma and the most common renal neoplasm in infants less than 3 months of age. It typically presents as an asymptomatic, unilateral palpable abdominal mass and is often associated with polyhydramnios, prematurity, and neonatal hypertension. Radical nephrectomy is often curable, although chemotherapy is recommended if tumor removal is incomplete or if there is tumor rupture during surgery. Local recurrence and metastases to the brain, lung, and liver are seen in 5%, usually within one year of nephrectomy. Overall survival rate is 90% if nephrectomy is performed early in the clinical course.

Conclusion: There are only 4 cases in the English literature of cellular CMN presenting with hemorrhagic manifestations, and no cases of intestinal necrosis or perforation associated with cellular CMN. Physicians should be aware of this exceedingly rare complication.