Neonatal Gardner fibroma: a sentinel presentation of severe familial adenomatous polyposis.

Familial adenomatous polyposis (FAP) is a rare cause of colorectal cancer and rarely presents in early childhood. Various extracolonic manifestations, however, may be present before the development of overt polyposis. One of the rarest manifestations is the Gardner fibroma (GAF), which has particular histologic features. Here we report the case of a child who presented in the neonatal period with a paraspinal mass. Although the initial diagnosis was unclear, biopsy of a second lesion at 32 months of age, and a review of the first lesion, resulted in the diagnosis of GAF. After rectal bleeding at 47 months, colonoscopy revealed 75 to 100 colonic polyps. Adenomas were identified in multiple biopsies throughout the colon and from several polyps located in the duodenum. Polyps were visualized in the jejunum by wireless-capsule endoscopy. A total proctocolectomy was performed, and no malignant transformation was observed in the colon on pathologic inspection. A truncating mutation in APC (c.4479_4480delGG p.Glu1494LysfsX19) was identified in the child. Her parents and sister do not carry this mutation in lymphocyte DNA. To our knowledge, this is the first report of neonatal GAF as the presenting feature of a molecularly confirmed case of sporadic FAP and the earliest colonic and small bowel involvement reported of FAP. It illustrates the need to exclude FAP in a child who harbors fibromas suggestive of GAF, even in the absence of supportive evidence of FAP in the patient or relatives.