Case Study: Fetus PapyraceusKristen Kirsch; Walt Bugielski, PA (ASCP); Pradeep Sethi, MD; Michelle Costas, PA (ASCP); Justin

Falcon, PA (ASCP)Allegheny General Hospital – Pittsburgh, PA

CLINICAL BACKGROUND:

GROSS FINDINGS:

CONCLUSIONS:

References:1. Kalousek, D.K, Fitch, N, Paradice, B.A. Pathology of the Human Embryo and Previable Fetus – An Atlas. New York, NY: Springer-Verlag; 1990.2. Saul, R.A, Stevenson, R.E, Rogers, R.C, Skinner, S.A, Prouty, L.A, Flannery, D.B. Growth References From Conception To Adulthood. Supplement

Number 1. Greenwood, SC: Greenwood Genetic Center; 1988.3. Benirschke, K, Burton, G.J, Baergen, R.N. Pathology of the Human Placenta. Berlin, Germany: Springer-Verlag; 2012.4. Baldwin, V.J. Pathology of Multiple Pregnancy. New ork, NY: Springer-Verlag; 1994.5. Kumar, V, Abbas, A, Aster, J. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Philadelphia, PA: Elsevier Saunders; 2015.

DISCUSSION:Fetus papyraceus (also recently known as vanishing twin phenomenon) is a

condition in which there is a compressed, flattened, involuted twin fetus and the surviving twin develops normally. This usually occurs in the second trimester with the co-twin being delivered in the third trimester. The fetus must die in the twelve to twenty week period but must be delivered after twenty weeks. It becomes compressed to fetal papyraceus by the growing sac of the living twin as the fluid of its own amniotic sac is resorbed. Monochorionic and fused dichorionic twins can present with this condition; the fetus can be found within the placental membranes.

The twin that survives can have anomalies as well. These consist of ileal atresia, congenital skin defects, limb amputations and gastroschisis. The mechanism of these complications is unknown. The umbilical cord around the leg of the monoamniotic twin can result in in amputation of the leg. Transamniotic vascular complications can result in disseminated intravascular coagulopathy following the death of the co-twin4. Studies have shown that the surviving twin can develop normally.

The deceased twin can have various amounts of compression. Normally they are tan-gray with extensive tissue autolysis. Cause of death is difficult to determine in these cases; this may be due to to anomalous cord insertion (i.e. velamentous), severe twin-twin transfusion syndrome (vascular anastomoses) or cord entanglements. The thorax is flattened and the entire surface is gray-yellow, slightly dry. The epidermis shrinks to a single layer which may represent remnants of the basement membrane. No bloating or swelling is grossly identified. The liver appears as a mass of yellow material inferior to the diaphragm. Male fetuses are more affected than female fetuses. The placental features are due to cessation of fetal circulation in that portion of the placenta associated with the deceased twin. Thus, this leads to gradual reduction of maternal circulation to that villous area which leads to ischemic damage and eventual collapse of villi. The compaction is associated with increased fibrin deposition around the villi.

When the fetus dies, the mother may experience amniotic fluid leaks, sudden lower abdominal pain and vaginal bleeding. There may be a period of rapid uterine growth then followed by a slowed or normal growth pattern.

In this case, composite gestational age was determined using tables and graphs provided using both long bone measurements and presence of ossification centers. During the process of embryogenesis, bones develop from cartilage molds which are created from mesenchymal precursor cells. Primary ossification centers located in the diaphysis, which provide radial bone growth, appear during gestational weeks 7 to 12 in the long bones. These are the areas of bone that ossify first; the clavicle and mandible are first to ossify. Secondary ossification centers occur when endochondral ossification progresses away from the center of the bone. The cartilage that becomes trapped between these two centers is known as the growth plate. In this case, ossification centers were found at the terminal fifth phalange of the foot and the fifth middle phalanx of the hand; this corresponds to a approximate gestational age of at least 12 weeks.

Figure 1. Fetus papyraceus with attached umbilical cord.

Figure 2. Opposing aspect of fetus papyraceus with attached umbilical cord.

Figure 4. X-ray of longer exposure to display phalanges of hands and feet.

Figure 3. X-Ray image to display rib, vertebra and long bones of arms and legs.

Figure 5. Infarcted placenta post-formalin-fixation.

In the case reviewed, a 28-year-old female presented with severe pre-eclampsia and diet maintained gestational diabetes. The patient had previous prenatal ultrasound to diagnose diamniotic-dichorionic twin gestation during the first trimester. Subsequent ultrasound determined demise of twin “B” at approximately 13.5 weeks gestational age (clinically). The remainder of the pregnancy was reported unremarkable.

The patient presented to West Penn Hospital for delivery at 37 weeks gestation. The fetus failed to descend and a primary low cervical transverse caesarean section was performed. A viable female infant (twin “A”) weighed 2730 grams (6 lbs.).

The placenta for twin “A” and the products of conception for twin “B” were sent to Allegheny General Hospital surgical pathology.

The specimen was received in pathology as two separate parts.

Part 1 was the placenta for the surviving twin – “A”. It consisted of a 592g , 19.0 x 15.3 x 3.2 cm, ovoid placental disc with attached membranes and umbilical cord. The umbilical cord and membranes were grossly unremarkable. The fetal surface of the disc was glistening, pale blue-gray with peripherally located areas of tan-yellow subchorionic fibrin deposits. The maternal surface was complete, intact and sectioning revealed three, tan-yellow, firm areas of induration measuring up to 1.5 cm in greatest dimension. The remaining parenchyma was red-brown, congested and spongy.

Part 2 was the remaining products of conception – twin “B”. It consisted of a fetus with attached umbilical cord and a placenta with attached membranes. The placental disc was 50g, 10.0 x 8.0 x 0.5 cm and ovoid. The fetal surface was pale, tan-pink with no grossly identifiable vasculature. The maternal surface was pale, tan-pink with no demarcation of the cotyledons. Sectioning revealsed pale, tan-pink parenchyma with gray-white areas, consistent with infarctions.

The fetus measured 9.2 cm crown to rump, 12.7 cm crown to heel and had a foot length of 1.2 cm. The skin was dessicated and sloughing. The attached umbilical cord was severely dessicated, red-pink and three blood vessels were identified. No cleft lip or palate were grossly identified. The fetus was phenotypically female based on external and internal genitalia. Opening revealed severe autolysis and desiccation of the organs; the heart appeared anatomically normal; the kidneys were not cystic; the lungs had ribbed grooves. Ossifications were identified at the terminal fifth phalanx of the foot and fifth middle phalanx of the hands. Composite gestational age was appropriate for 14 weeks on growth patterns.

LONG BONE MEASUREMENTS

Femur 1.6 cm ~14 weeks

Tibia 1.4 cm ~14 weeks

Fibula 1.5 cm ~14 weeks

Humerus 1.8 cm ~14 weeks

Radius 1.6 cm ~15 weeks

Ulna 1.7 cm ~14 weeks

DIAGNOSIS:The first part was a placenta weighing 592 grams which was consistent with athird trimester placenta (between 10th and 50th percentile). It displayed mature chorionic villi and increased syncytial knots. There was reactive amnion and meconium-containing macrophages. Acute chorioamnionitis and focal villitis were present. The placenta displayed subchorionic fibrin deposition, infarct and intervillous fibrin thrombi. Additionally, there was a three-vessel umbilical cord present.

The second part were products of conception consisting of an infarcted placenta weighing 50.0 grams, autolyzed membranes and cords. Acute and chronic deciduitis was present. Additionally, there was a fetus papyraceous with 1.6 cm femur, 1.4 cm tibia, 1.5 cm fibula, 1.8 cm humerus, 1.6 cm radius and 1.7 cm ulna. Ossifications were identified at the terminal phalangeal of the foot and the first metaphalanx of the hands. The composite gestational age is approximated at 14 weeks.

Figure 6. Example of fetus papyraceus dissected from the placenta.3

This case demonstrated a fetus papyraceus. The overall rate of this phenomenon is 1 in every 180 to 190 twin pregnancies. The cause is unknown in most circumstances as confirmed in this case. The placenta was highly infarcted as it seems to not have received enough of the maternal blood supply. The fetus was compressed; the skin was desiccated and sloughing upon receipt of the specimen confirming this diagnosis. The heart was intact and no abnormalities were identified. The condition of the surviving infant is unknown at this time, but she could have a list of potential anomalies as described above.