Perinatal detection of familial adenomatous polyposis.

Hepatoblastoma is an uncommon fetal neoplasm that may represent an isolated malignancy or a component of a familial cancer or syndromic diagnosis. A large fetal liver mass was detected on routine ultrasound examination of a 23-year-old woman with thyroid nodules and hypertension. Inferior vena cava compression prompted delivery; postnatal biopsy revealed hepatoblastoma. Maternal thyroid biopsy revealed papillary carcinoma. Neonatal and maternal cytomolecular analysis revealed APC gene disruption at 5q22.2. Pedigree analysis exposed multigenerational colon cancer and thyroid cancer, which in conjunction with genetic testing is consistent with familial adenomatous polyposis. This is a novel means of familial adenomatous polyposis diagnosis. Obstetricians and perinatologists should be alert for familial cancer or syndromic diagnoses presenting as fetal neoplasms.