An interesting pathological specimen at delivery

A 26 year old gravida 2 para 1 woman presented in the third trimester of her pregnancy. She had not had antenatal check ups, but was in good health. She had attended a first trimester scan, and said that the doctor told her she was having twins. She had a family history of twins. Her first pregnancy had resulted in a full term normal vaginal delivery. Routine antenatal checks all were normal. Ultrasonography showed a normally growing fetus, appropriate for dates, and a cystic flattened mass near the placenta. No blood flow to the cystic mass could be seen. At term she delivered a 3200 g male infant by normal vaginal delivery. After the delivery, a pathological specimen was delivered along with the remnants of the placenta. The placenta showed a calcified and nodular area on the fetal surface. Microscopic examination of the placenta showed nests of epithelioid cells and deposits of fibrin. There were no postpartum complications.⇓ Fig 1 Specimen delivered after the normal fetus (top) and calcified nodular surface (arrow) of the placenta (bottom)