In Utero Development of Hypertensive Necrotizing Pulmonary Arterial Lesions

In Utero Development of Hypertensive Necrotizing Pulmonary Arterial Lesions: Report of a Case Associated with Premature Closure of the Ductus Arteriosus and Pulmonary Hypoplasia Calvin E. Oyer, MD,* Lloyd R. Feit, MD,† Beverly B. Rogers, MD,‡ and Charles Kuhn, MD§储 Departments of *Pathology and †Pediatrics, Women and Infants’ Hospital and Brown University School of Medicine, Providence, Rhode Island, USA; ‡Department of Pathology, Children’s Medical Center and Southwestern Medical School, University of Texas, Dallas, Texas, USA; §Department of Pathology, Memorial Hospital of Rhode Island, Pawtucket, Rhode Island, USA; 储Department of Pathology, Brown University School of Medicine, Providence, Rhode Island, USA

ⴙⴙ Premature closure of the ductus arteriosus (PCDA) is an uncommon defect in which pulmonary hypertension (PH) has been documented by echocardiography in patients and by direct measurement after experimental PCDA in animals. The pulmonary vascular histology in human cases has received little attention but in the few recorded observations the vessels were either normal or showed increased muscularity. We report the case of a 31 week hydropic female stillborn monozygotic twin in whom postmortem examination disclosed PCDA and hypoplasia of the lungs. Atypical plexiform lesions with necrotizing pulmonary arteritis were present. These lesions represent vascular consequences of severe pulmonary hypertension produced by greatly enhanced blood flow through a restricted vascular bed resulting from the combined effects of these two abnormalities. The findings in this case of PCDA with presumed severe PH indicate that severe pulmonary vascular changes can develop in utero and that the interval of time needed for development of such changes in secondary PH is relatively short. Cardiovasc Pathol 2000;9:39–47 © 2000 by Elsevier Science Inc.

Premature closure of the ductus arteriosus (PCDA) in utero is a relatively rare event which can be isolated or associated with major cardiac anomalies. It can occur without known cause or be secondary to medication and can be fatal or merely cause transient physiological effects. The effects of PCDA on pulmonary vascular structure have been evaluated experimentally but have received scanty attention in clinical cases. Hypertensive lesions of the muscular pulmonary arteries are often graded on the scale of Heath and Edwards (1): where grade I is medial hypertrophy; grade II is cellular intimal thickening; grade III is intimal thickening with fibrosis; grade IV is plexiform lesions included; grade V is plexiform lesions with dilation lesions and vein-like arteries; Manuscript received July 8, 1999; accepted September 23, 1999. Address for correspondence: Calvin E. Oyer, MD, Department of Pathology, Women and Infants’ Hospital, Providence, RI 02906, USA. Tel: (401) 831-2465; Fax: (401) 274-5519; E-mail ⬍[email protected]⬎. Cardiovascular Pathology Vol. 9, No. 1, January/February 2000:39–47  2000 by Elsevier Science Inc. 655 Avenue of the Americas, New York, NY 10010

and grade VI is arterial necrosis. Grade I–III lesions are reversible if the hypertension diminishes. Grades IV–VI are generally irreversible and have not been noted to be present at birth (2). Although the grading scheme implies a temporal sequence, Wagenvoort has suggested that fibrinoid necrosis can precede the formation of plexiform lesions (3), a suggestion that has some experimental support (4). We report necrotizing pulmonary arteritis with atypical plexiform lesions in a stillborn with PCDA, hydrops, and pulmonary hypoplasia.

Case Report A 2613 gram hydropic female stillborn fetus, monozygotic twin B, was delivered at 31 weeks, 6 days gestation to a 37-year-old gravida 2 para 2 mother. Prenatal ultrasound had shown a normal twin A, but twin B was hydropic with severe ascites. The right ventricle (RV) had a thick wall and

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a small chamber. The mother’s blood type was A, Rh positive, and the antibody screen was negative. She had kidney stones in the past. The previous pregnancy was uneventful and resulted in delivery of a normal girl. Both twins were alive at the start of preterm labor which commenced after spontaneous rupture of membranes. Meconium staining was noted. The single disc twin placenta was meconium-stained with diamnionic, monochorionic membranes. Surface vascular anastomoses were seen. Villous edema and nucleated red blood cells in fetal vessels were seen in the placental parenchyma of both twins. Twin A weighed 1330 grams and had a Dubowitz score consistent with 30 weeks gestation, and initial hemoglobin and hematocrit values of 19.9 g/dl and 55.7%, respectively. Growth parameters were at 50th percentile for 30 weeks gestation. A bicuspid aortic valve and coarctation of the aorta were demonstrated by echocardiography. An amniotic band was attached to the right calf and the right foot was edematous. She had a contracted fifth digit of the left hand and a hypoplastic nail of the second toe. She had a normal female karyotype and went home at fifty days of age. When she was 20 months of age the coarctation was repaired. On subsequent examination she has a satisfactory surgical repair and a nonobstructive bicuspid aortic valve. Twin B was stillborn and an autopsy was performed. The left foot length was 5.4 cm and the right 6.0 cm. The crown-

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rump length was 30.5 cm and the body length 42.5 cm. The gestational age could not be accurately assessed by these external measurements, but they were not incompatible with the clinical estimate of almost 32 weeks. Hydrops was present with marked subcutaneous edema and 290 ml of fluid in the peritoneal cavity and 45 and 52 ml in the right and left pleural cavities, respectively. Talipes equinovarus and radial deviation of the hands were present bilaterally. The entire body was dusky and the hands were markedly cyanotic. The combined heart and lung weight was 20.5 grams (normal 30.5 ⫾ 13.2 grams for 31 weeks gestation) (5). The lungs appeared hypoplastic. The brain weighed 87 grams (normal 178 ⫾ 32). It was firm and polymicrogyria was especially prominent in the frontal and parietal regions. Focal germinal matrix hemorrhage had occurred in the right hemisphere. The heart (Figure 1) occupied a normal position. The aorta and its branches were normally developed and properly placed with normal peripheral vessels including three vessels in the umbilical cord. The atria were dilated. The thicknesses of the right ventricular wall, septum, and left ventricular wall were 0.7 cm, 0.45 cm, and 0.45 cm, respectively (normal upper limits for age and body length; RV 0.4 cm, LV 0.6–0.7 cm) (6). The right ventricular chamber was small and the right ventricular outflow tract was narrowed by an hypertrophied parietal band. The pulmonary valve

Figure 1. The heart and great vessels with portion of left lung attached. The aorta (A) and pulmonary trunk (P) are of equal diameter. The ductus arteriosus (arrow) is markedly reduced in external diameter.

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Figure 2. The distal pulmonary trunk and closed ductus arteriosus. The origins of the right and left pulmonary arteries can be seen (R and L). No ductal lumen can be identified in the expected location (arrowhead).

was normal and the pulmonary trunk was of the same diameter as the aorta. The ductus arteriosus was closed (Figure 2). The atrial septum was normally formed with a patent foramen ovale. The valve of the foramen ovale (septum pri-

mum) was a thin, wrinkled structure, but intact and of adequate size. Microscopically, a mild to moderate number of nucleated red blood cells were seen in fetal vessels. The myocar-

Figure 3. Parent vessel and atypical plexiform lesion (L) in peribronchial location: bronchus not shown. Note focal intimal thickening (arrows) and thickening of media (white letter M) in wall of parent vessel (trichrome ⫻100).

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Figure 4. Atypical plexiform lesion illustrating right angle branching of the involved vessel from an obliquely-sectioned parent arterial vessel whose lumen (O) is labeled (H&E ⫻100).

dium appeared normal with no myocardial fiber disarray. Dysplasia of the cerebral cortex and cerebellum with polymicrogyria was present and the focal germinal matrix hemorrhage was confirmed. The lungs were hypoplastic with large bronchi near the surface. Striking abnormalities were present in muscular pulmonary arteries accompanying the distal bronchi and bronchioles. Arteries in the range of 120 to 445 micra in diameter showed thickening of the media and focal intimal fibrosis (Figure 3). Side branches showed round or oval ex-

pansions 180 to 475 micra in diameter consisting of disorganized proliferation of spindle-shaped cells often with several small vascular lumina (Figures 3 and 4). Elastic trichrome staining revealed destruction of elastic tissue and disappearance of the regular structure of the underlying vessel wall (Figure 5). Little stainable connective tissue contributed to the lesions. Smudgy fibrinoid staining was present in many lesions, particularly around smaller vascular lumina at the periphery of the lesions (Figure 6). Extravasated red blood cells and erythrocyte fragments were

Figure 5. Destruction of elastic tissue in parent vessel and absence of elastic tissue within the lesion. Red blood cells within the lesion are fragmented (elastic trichrome ⫻100).

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Figure 6. Fibrinoid necrosis (arrows) of small vessels branching from the lesion (H&E ⫻190).

scattered throughout the lesions and hemosiderin-containing macrophages were present in some. A few lesions were surrounded by a mantle of lymphocytes and eosinophils. The lesions resembled plexiform lesions in their multiple vascular lumina, but invariable lacked the downstream dilation lesions of the typical mature plexiform lesion complex. Immunoperoxidase staining was carried out to characterize the lesions further. Antigen retrieval using a steamer and Dako HIER target retrieval solution was carried out according to the manufacturer’s instructions. Primary antibodies are listed in Table 1. Bound antibody was detected using secondary antibodies conjugated to a peroxidase-labeled polymer and the EnVision peroxidase system (Dako) as recommended by the manufacturer. All of the cells comprising the vascular lesions stained for vimentin (Figure 7A). Many also stained for smooth muscle alpha actin, sometimes highlighting the presence of multiple vascular channels (Figure 7B). Staining for factor VIII associated antigen (mainly for

Table 1. Primary Antibodies Antigen CD3 CD20 CD31 CD34 CD43 CD68 Alpha smooth muscle actin Vimentin Factor VIII assoc. Antigen

Source

Host

Clone

Dako Dako Dako Novocastra Dako Dako

Rabbit Mouse Mouse Mouse Mouse Mouse

L26 JC/70A QBEND/10 DF-T1 PG-M1

Sigma Signet

Mouse Mouse

1A4 V9

Dako

Mouse

F8/86

von Willebrand factor) showed deposition of the antigen in the extracellular matrix which obscured cellular staining (Figure 7C). Rare spindle cells stained for the endothelial markers CD31 and CD34 and these antigens confirmed the presence of multiple vascular lumina in some lesions (Figure 7D). CD68 positive macrophages were numerous at the periphery and surrounding the lesions. CD20 B-lymphocytes and CD3 or CD43 T-lymphocytes were few.

Discussion Long known to occur in the presence of tetralogy of Fallot or persistent truncus arteriosus (7,8), PCDA was first described as an isolated abnormality in 1969 by Arcilla et al. (9) in a survivor whose mother had received salicylates for acute polyarthritis. Isolated PCDA occurs, either as a spontaneous lesion (10) or secondary to medication administered to the mother. Indomethacin has been incriminated, whether given for hydramnios (11) or for preterm labor (12,13). Harlass et al. (7) cited 5 previous cases (10,14) in which no causative medication was involved, but a detailed medication history was lacking. Initially diagnosed only after birth, either at autopsy or by hemodynamic studies, PCDA has, in the modern era, been recognized in utero using Doppler echocardiography (15,16). Suggested diagnostic criteria in the neonate include massive transient tricuspid regurgitation and atrial right to left shunt, a minimally patent or closed ductus which fails to respond to prostaglandin, and a dilated aorta with absence of normal hypoplasia of the isthmus (17). Some data suggest that PCDA is associated with a larger than normal foramen ovale (18) due to right ventricular outflow tract obstruction and resultant increased right to left atrial level shunting in utero.

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Figure 7. Immunoperoxidase results. (A) Staining for vimentin showing positivity of cells in walls of vascular channels and the spaces between them (⫻190). (B) Staining for smooth muscle alpha actin. Positive cells often enclose vascular lumina (⫻190). (C) Staining for factor VIII. The antigen is present in subendothelial matrix of muscular artery and is diffusely present in within the lesion (⫻190). (D) Staining for CD34. Staining is present in endothelial cells lining large and small vascular channels (⫻100).

Reports of PCDA in twins have been rare. Hallak et al. (12) reported a dizygotic male twin with PCDA. The mother received indomethacin for premature labor and his twin sister was normal. Both twins survived. Kohler (10) cited an 1882 report of “a closed ductus in one of aborted twins”; the other twin was normal and zygosity was not stated. Twin transfusion and twin reversed arterial perfusion syndromes

have been associated with calcifications in the wall of large pulmonary arteries (19), but PCDA with either of these syndromes has not been reported. The present case is the only reported one of PCDA involving twinning of known monozygosity. The existence in the living twin of coarctation of the aorta and a bicuspid aortic valve raises the question of a genetic or multifactorial predisposition to vascular anomalies in this pair.

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Figure 7. Continued.

Haller et al (20) ligated the ductus arteriosus (DA) in fetal pups in utero. At delivery, the pups had dilation and hypertrophy of the RV, dilation of the preductal pulmonary artery (PA), and hepatic congestion. The PA was 3–4 times larger than the aorta and the preductal PA contained organized thrombi. The vasculature within the lungs was not described. Fetal sheep, studied after injecting ewes with indomethacin in late gestation, had pressure differences across the DA as early as 30 minutes post-injection (21). After PH of 1 to 4 days duration, pulmonary vasculature was compared with control fetuses. Significantly increased medial width and decreased external diameter of resistance

pulmonary arteries were noted (22). In another ovine study increased muscle was seen in the walls of acinar and preacinar vessels 6 to 17 days after in utero ligation of the DA (23) Neither plexiform lesions nor lesions of arteritis or thromboembolism have been reported after ductal ligation in utero. Pulmonary vessels have only occasionally been described in reports of PCDA in humans. Becker et al. (14) found normal pulmonary vasculature in two cases. In assessing three stillborns with PCDA, Kohler (10) mentioned “marked engorgement of the pulmonary vessels and thickening of the walls” in one of three fetuses with PCDA.

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Downing and Thibeault reported increase in medial wall thickness with decrease in external diameter in preacinar arteries as well as increased muscularization of the acinar vessels (24). Tada et al. (25) saw no medial hypertrophy in the pulmonary vessels in a premature infant with PCDA and prune belly syndrome in spite of complete obstruction of the DA and slight dilation of the RV and right atrium. There have been no reports of pulmonary arterial lesions resembling those seen in the present case. The possibility that the vascular lesions in this case represent organizing thromboemboli secondary to shared vascularity in a monochorial twin placenta was considered but rejected due to the prominent cellularity of the lesions, the uniformity of size of the involved vessels, the presence of fibrinoid necrosis, and the destruction of the elastic lamina (26). The pulmonary arterial lesions in the present case, grade VI, were far more severe than those cases reported in the literature. Some reported cases were examples of indomethacin-induced constriction of the ductus causing narrowing, whereas in the present case, the lumen of the ductus was completely obliterated. In experimental animals, however, the ductus has been obliterated by ligation, with only low grade hypertensive remodeling as a result. In the present case the lungs appeared grossly and microscopically hypoplastic and the weight of the heart-lung block was low. We assume a reduced weight of the lungs in the present case considering that experimental and clinical premature closure of the ductus is associated with an enlarged heart and that this heart appeared enlarged and had right ventricular hypertrophy by wall measurement. In fact, even if one makes the most conservative assumption and subtracts the normal heart weight for gestational age from the weight of the heart-lung block and uses the body weight of twin A (because the weight of twin B is uninformative due to hydrops), the lung/body weight ratio becomes 0.0094, compared to a lower limit of normal of 0.012 (27,28). Hydrops is a recognized effect of PCDA (7,24) and, in turn, is a known cause of pulmonary hypoplasia (29). Therefore the pulmonary hypoplasia can be regarded as a complication of PCDA rather than an independent anomaly. Pulmonary hypoplasia restricts the vascular bed exacerbating the increased pressure caused by the ductal closure and resulting in the unusually severe lesions seen in this case. We are unaware of previous reports of high grade pulmonary vascular disease occurring before a postnatal age of 2 months (2) possibly because of a protective effect of the thick media of fetal arteries compared to those of older children and adults (30). The findings in this case of PCDA with presumed severe PH indicate that severe pulmonary vascular changes can develop in utero and that the interval of time needed for development of such changes in secondary PH is relatively short. Our thanks to Don B. Singer, MD, for his input into our evaluation of the case and for helpful manuscript review.

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