Prenatal diagnosis of an infantile fibrosarcoma causing gastroesophageal obstruction requiring total gastrectomy

Infantile fibrosarcoma (IFS) is a rare neoplasm with variable presentations. We report a case of a prenatally-diagnosed tumor, ultimately identified to be an IFS, involving the distal esophagus, proximal stomach, diaphragm, and pancreas. The large tumor obstructed the gastroesophageal junction, leading to polyhydramnios and a precipitous delivery. Postnatal biopsy revealed malignant spindle cells consistent with IFS, which expressed an EGFR internal tandem duplication involving exons 18–25 (EGFR-KDD). Neoadjuvant treatment with vincristine/actinomycin lead to a good anatomic response and subsequent gross total resection. To our knowledge, this is the first reported case of IFS involving the upper gastrointestinal tract containing this mutation.