A 5-month-old girl, already malnourished, came to the doctors with a belly that kept getting bigger. Imaging showed a mass with multiple fluid-filled pockets deep in her abdomen. A biopsy turned up pancreatic tissue, so her doctors suspected a pancreatic pseudocyst, a walled-off fluid collection, and also considered a malformation of the lymphatic vessels in the tissue that anchors the intestines.
Neither was right. Over two weeks, fluid built up in her abdomen faster than repeated large-volume drainage could remove it, until the pressure led to respiratory collapse and abdominal compartment syndrome. Surgeons removed the mass, and under the microscope it held benign mature and immature tissue from the nervous system, the eye, the airways and connective tissue. It also contained something the authors say had not been described in this kind of tumor: an inflamed layer of amniotic membrane.
