Atlas pediatric perinatal pathology


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Atlas pediatric perinatal pathology

  1. 1. Pediatric-Perinatal PathologyTutorials Malformations and Deformations: 1. Cleft lip, gross 2. Lateral cleft lip, gross 3. Facial abnormalities, gross 4. Hands with abnormal crease, gross 5. Omphalocele, gross 6. Gastroschisis, gross 7. Limb-body wall complex, gross 8. Limb-body wall complex, gross 9. Alobar holoprosencephaly, gross 10. Semilobar holoprosencephaly, gross 11. Holoprosencephaly, gross 12. Hydranencephaly, gross 13. Syndactyly, hand and foot, gross 14. Syndactyly, hand, gross 15. Bowel atresia, gross 16. Duodenal atresia, gross 17. Colonic atresia, gross 18. Tracheo-esophageal fistula and atresia, gross 19. Sirenomelia, gross 20. Intrauterine fetal demise, external features, gross 21. Recessive polycystic kidney disease, gross 22. Diaphragmatic hernia, gross 23. Diaphragmatic hernia, gross 24. Renal agenesis, gross 25. Potter facies from oligohydramnios, gross 26. Potter facies and glove-like hand from oligohydramnios, gross
  2. 2. 27. Normal chest cavity, gross28. Pulmonary hypoplasia, gross29. Pulmonary hypoplasia, microscopic30. Varus deformities, feet, gross31. Rocker bottom foot, gross32. Clenched hand, gross33. Hydrops fetalis, gross Abnormalities of Twinning:34. Siamese twins (craniothoracopagus), gross35. Siamese twins (thoracopagus ), gross36. Acardius acephalus (chorangiopagus parasiticus), gross37. Acardius anceps (chorangiopagus parasiticus), gross38. Twin-twin transfusion syndrome, gross Neural Tube Defects:39. Meningomyelocele, gross40. Meningomyelocele, gross41. Anencephaly, gross42. Anencephaly, gross43. Anencephaly, gross44. Iniencephaly, gross45. Rachischisis, gross46. Iniencephaly, encephalocele, rachischisis, gross47. Exencephaly, gross Pediatric Neoplasia:48. Nasopharyngeal teratoma, congenital, gross49. Teratoma, congenital, low power microscopic50. Lymphangioma, congenital, gross51. Lymphangioma, congenital, medium power microscopic52. Lymphangioma, congenital, medium power microscopic53. Hemangioma, congenital, gross54. Wilms tumor, gross
  3. 3. 55. Wilms tumor, medium power microscopic56. Neuroblastoma, gross57. Neuroblastoma, medium power microscopic58. Rhabdomyosarcoma, low power microscopic59. Rhabdomyosarcoma, medium power microscopic Congenital Infections:60. Congenital syphilis, gumma in heart, gross61. Spirochetes (Treponema pallidum), microscopic62. Cytomegalovirus, congenital, kidney, microscopic63. Parvovirus, congenital, spleen, microscopic64. Congenital pneumonia, microscopic Complications of Prematurity:65. Hyaline membrane disease, lung, microscopic66. Bronchopulmonary dysplasia, lung, microscopic67. Germinal matrix, brain, normal and with hemorrhage, low power microscopic68. Intraventricular hemorrhage, gross69. Intraventricular hemorrhage, severe, gross70. Kernicterus, brain, gross71. Neonatal necrotizing enterocolitis (NEC), gross72. Neonatal necrotizing enterocolitis (NEC) and normal bowel, low power microscopic Miscellaneous Conditions:73. Pyloric stenosis, gross74. Meconium ileus, gross75. Meconium ileus with peritonitis, gross76. Hirschsprung disease, gross77. Pneumatosis intestinalis, microscopic78. Normal skin with hair, gross79. Accessory spleens, gross80. Postmaturity with prominent fingernails, gross
  4. 4. 81. Maceration, gross82. Fetal chest with thymus, gross83. Thymus with macrophages, low power microscopic84. Subgaleal hemorrhage, gross85. Meconium aspiration, medium power microscopic86. Meconium aspiration, high power microscopic
  5. 5. Examination of a stillborn fetus or neonate should consist of acareful and detailed physical examination. You must note thepresence of any anomalies, as well as detail size and gestationalage. The anomaly seen in this photograph, a large bilateral cleft lip,is not so subtle, but some anomalies are. Call a clinical geneticist forconsultation. The presence of one anomaly suggests that additionalanomalies may be present, including internal anomalies such ascongenital cardiac defects that may be life-threatening.
  6. 6. Here is a lateral cleft in a child with multiple congenital anomalies. Inthis case, the constellation of anomalies suggested a possiblechromosomal anomaly, and a karyotype revealed 47, XY, +18(trisomy 18).
  7. 7. The facial features shown in the 3rd trimesterfetus above and the 2nd trimester fetus beloware typical for trisomy 18 (e.g., 47, XY, +18).The face is small in proportion to the head, withmicrognathia.
  8. 8. There is an abnormal transverse crease across the palm of eachhand seen here. Together with the single flexion crease on the 5thdigit, this is quite typical for trisomy 21 (e.g., 47, XX, +21).
  9. 9. Here is a ventral abdominal wall defect. This defect involves theregion of the umbilical cord, so this is an omphalocele. Note thatthere is a thin membrane covering the herniated abdominal contents(loops of bowel can be seen under the membrane). This defectwould have to be repaired over a period of time. Since the bowel hasmainly developed outside of the abdominal cavity, it is malrotatedand the cavity is not properly formed (too small).
  10. 10. This is large lateral abdominal wall defect does not involve the umbilicalcord and is not covered by a membrane. This is a gastroschisis. Muchof the bowel, stomach, and liver are herniated outside the abdominalcavity.
  11. 11. This is a gastroschisis in association with a limb-body wall (LBW)complex. This complex is sometimes called "amnionic band syndrome"but such bands may only be present in half of cases of LBW complex.Seen here in association with LBW complex are reductions of theextremities, particularly the left upper extremity, and scoliosis. Not seenhere are craniofacial clefts and defects that can also occur with LBWcomplex.
  12. 12. This is limb-body wall (LBW) complex with constricting amnionicbands. The bands, as well as the other defects, may arise from earlyembryonic disruption with formation of adhesions and subsequentabnormal formation and loss of structures such as extremities andabdominal wall.
  13. 13. This is holoprosencephaly, often accompanied by the failure of fetalfacial midline structures to form properly. Hence, there are usuallymidline facial defects (cleft lip, cleft palate, cyclopia, etc) accompanyingthis condition. The "alobar" form of holoprosencephaly is shown here inwhich there a single large ventricle, because there is no attempt toform separate cerebral hemispheres. This condition may be associatedwith trisomy 13. It may rarely occur in association with maternaldiabetes mellitus.
  14. 14. The skull is opened here to reveal the "semilobar" form ofholoprosencephaly, because there is a small cleft representing anattempt to separate the hemispheres. There is no gyral pattern herebecause this stillborn fetus was under 20 weeks gestation.Holoprosencephaly is a grave condition with little or no brainfunction. Holoprosencephaly can be associated with chromosomalanomalies (such as trisomy 13), with maternal diabetes mellitus, andcan be seen sporadically.
  15. 15. Here is a cross section though a brain with holoprosencephaly,revealing a single ventricle. Toward the base of the brain are the fusedthalami typical of this process.
  16. 16. This is hydranencephaly. The brain is essentially a bag of water,because an intrauterine vascular accident involving the brain led tolack of blood flow and subsequent loss of cerebral tissue.
  17. 17. Syndactyly represents fusion of two or more digits. It can be anisolated finding or part of syndromes that define patterns ofanomalies. Most of these syndromes do not have a specific geneticdefect yet defined, though some do. Seen above are the digits of thehand fused together. Below, the foot has rudimentary, partially fuseddigits.
  18. 18. Here is an example of syndactyly in which the 3rd and 4th fingersare fused into one large digit. This particular pattern can be seenwith triploidy (69 chromosomes).
  19. 19. The meconium-filled bowel ends in a blind pouch. This is atresia ofthe bowel. Such a defect, like many anomalies, often happens alongwith other anomalies. Bowel atresias are accompanied bypolyhydramnios, since the swallowing and absorption of amnioticfluid by the fetus is impaired.
  20. 20. There is a point of marked narrowing indicative of congenital duodenalatresia depicted here. Interestingly, half of all duodenal atresias occurwith Down syndrome, although conversely, few cases of Downsyndrome have duodenal atresia. By ultrasound, there is a "doublebubble" sign from duodenal enlargement proximal to the atresiaaccompanying the normal stomach bubble. The normal esophagus,liver, and gallbladder are seen here as well.
  21. 21. This is a colonic atresia accompanied by additional anomalies,including a persistent cloaca that resulted from failure of the urogenitalseptum to form. The right testis and the left testis are cryptorchid, andthere is absence of the penis. The presence of one anomaly suggeststhat others are present as well, and the term "multiple congenitalanomalies" applies.
  22. 22. This is a tracheo-esophageal fistula with esophageal atresia. Theesophageal atresia is present in the mid-esophagus. Thetracheoesophageal fistula is located below the carina.
  23. 23. This is sirenomelia. The term comes from "siren" or "mermaid"because of the characteristic fusion of the lower extremities thatresults from a failure in the development of a normal vascular supplyto lower extremities from the lower aorta in utero.
  24. 24. The first thing to notice is the features of intrauterine fetal demise:skin slippage and reddening. These features are those ofmaceration and not trauma or birth defect. Note the shortened lowerextremities, known as phocomelia. It was idiopathic in this case, butin the 1950s the drug thalidomide was responsible for many caseswhen pregnant women took it. Thus, it is very important thatpregnant mothers be advised that drugs (including cigarette smokingand alcohol consumption) may have profound effects on the fetus.
  25. 25. The two enormous masses beneath the liver are cystic kidneys.This is an example of autosomal recessive polycystic kidney disease(ARPKD).
  26. 26. In this case, the diaphragmatic dome is missing on the left, allowingherniation of the abdominal contents into the chest cavity. The metalprobe in the photograph is behind the left lung, which has beendisplaced by the stomach. Below the stomach is a dark spleen (atthe white arrow). The white arrow overlies the left lobe of liver whichis extending upward.
  27. 27. A diaphragmatic hernia on the left allows herniation of bowel into the leftchest cavity. The herniating liver has become tilted vertically. Incursionof abdominal contents into the chest cavity will result in pulmonaryhypoplasia. Though diaphragmatic hernia may occur as an isolateddefect that is potentially repairable, most are associated with multipleanomalies, and often with chromosomal abnormalities.
  28. 28. Agenesis refers to the absence of formation of a body part inembryogenesis. Here the kidneys are absent from theretroperitoneum, and this renal agenesis will result inoligohydramnios, because amniotic fluid is mainly derived from fetalurine. The oligohydramnios leads to deformations such as aconstricted chest, diminished lung development, and pulmonaryhypoplasia.
  29. 29. This baby demonstrates the typical "Potters facies" with prominentinfraorbital folds resulting from oligohydramnios in utero. This is anexample of a deformation sequence in which an anomaly (here thelack of normal kidneys) leads to lack of fetal urine output withresultant oligohydramnios that causes deformation throughconstraint.
  30. 30. Seen in the right panel is the characteristic facial appearance witholigohydramnios, with prominent infraorbital creases and a flattenednose. In the left panel the hand appears to have excessive skinfolds, like a loose glove. Oligohydramnios restricts fetal movement.The umbilical cord may be short.
  31. 31. This is the normal appearance of the chest cavity in a neonate. Notethe prominent pink thymus above the heart in the mediastinum.Note the size of the heart in relation to the lungs and chest cavity.The diaphragmatic leaves are intact. The liver is normally quitelarge in neonates in relation to other organs.
  32. 32. The most serious consequence of oligohydramnios is pulmonaryhypoplasia. Note the extremely small lungs in this case on eachside of the heart in the middle of the chest. The chest cavity isopened here at autopsy and the lung appear small in comparison tochest size, but in utero the constriction from diminished amnionicfluid would have decreased the chest cavity size.
  33. 33. Microscopic examination of the lung reveals no alveolardevelopment, only tubular bronchioles incapable of significant gasexchange, in this premature baby with pulmonary hypoplasia fromoligohydramnios. This results in insufficient gas exchange fromrespiration following birth.
  34. 34. Deformation from constraint with oligohydramnios in utero can resultin the appearance of the club feet (varus deformity) seen here. Thefeet are turned inward.
  35. 35. This is the appearance of a "rocker bottom" foot with a prominentcalcaneus and rounded bottom. Such an anomaly may suggest achromosomal abnormality such as trisomy 18.
  36. 36. These are clenched hands resulting from camptodactyly (fingersbent over) and clinodactyly (fingers inclined to one side or the other).This particular appearance is very suggestive of trisomy 18.
  37. 37. Generalized edema from fluid collection in the soft tissues results inhydrops fetalis. There are many causes for fetal hydrops. The mostcommon are "non-immune" types that include infections, congestivefailure (from anemia or cardiac abnormalities), and congenitalanomalies. Immune hydrops, from maternal antibody formed againstfetal red blood cells, is not common when Rh immune globulin isemployed in cases of potential Rh incompatibility.
  38. 38. This is an uncommon complication of monozygous twinning in whichthere is fusion of the twins. The popular term is "siamese" twins. Thescientific term applicable in the case shown here iscraniothoracopagus, or twins joined at the head and chest. There isonly one brain, and the hearts and gastrointestinal tracts are fusedas well. The location and amount of fusion can vary.
  39. 39. This is an example of thoracopagus. Note the large omphalocele inthe lower abdomen shared by these monozygous twins. These twinsshared a heart and liver and several other organs were partiallyfused. Attempts at separation of such twins can either be viewed asheroic new technology or expensive futility. The survival rate withsignificant fusion of organs is essentially nil.
  40. 40. This is another abnormality of twinning in which one fetus isessentially a poorly formed blob attached to, or separate from, acomplete fetus. This condition is called acardius-acephalus becausethere is typically no heart or brain in the "blob" twin. The photographhere reveals an acardiac twin that consists mainly of just lowerextremities. Such a non-viable twin can be surgically removed.
  41. 41. This is a more complete acardiac twin in which actual body regionsare present. There were few poorly formed internal organs present.Nonetheless, it is non-viable.
  42. 42. If there is a vascular connection across a monochorionic twinplacenta, then a twin-twin transfusion syndrome can develop. In thiscondition, there is diminished blood flow to one twin (the "donor")and increased blood flow to the other twin (the "recipient"). The paleappearing donor is smaller and may die for lack of sufficient bloodflow. More commonly, the larger plethoric recipient may die fromcongestive heart failure.
  43. 43. Neural tube defects are are one of the more common congenitalanomalies to occur. Such defects result from improper embryonicneural tube closure. The most minimal defect is called spina bifida, withfailure of the vertebral body to completely form, but the defect is notopen. Open neural tube defects with lack of a skin covering, can includea meningocele, in which meninges protrude through the defect. Here isa large meningomyelocele in which the defect is large enough to allowmeninges and a portion of spinal cord to protrude through the defect.Such defects can be suggested by an elevated maternal serum alpha-fetoprotein (MSAFP).
  44. 44. This is a fetus from a termination of pregnancy via dilation andextraction, which is done in the second trimester. Note the largeneural tube defect in the lower back.
  45. 45. This is anencephaly. This condition occurs when there is failure offormation of the fetal cranial vault. The brain cannot form properlywhen exposed to amniotic fluid. Note that this fetus died in utero--there are signs of maceration, with skin slippage and reddening.
  46. 46. Note the absence of the cranial vault in this fetus with anencephaly.Supplementing the maternal diet with folate prior to and duringpregnancy can reduce the incidence of neural tube defects.
  47. 47. The eyes appear proptotic with anencephaly because of the lack ofthe skull. Note the low set external ear.
  48. 48. This is a slight variation of a neural tube defect known asiniencephaly in which there is lack of proper formation of occipitalbones with a short neck and defect of the upper cord. The head istilted back.
  49. 49. A severe rachischisis is shown here in a fetus that also hasiniencephaly.
  50. 50. Seen protruding from the back of the head is a large encephalocelethat merges with the scalp above. The encephalocele extends downto partially cover a rachischisis on the back. This fetus also has aretroflexed head from iniencephaly.
  51. 51. This form of neural tube defect is known as exencephaly. Thecranial vault is not completely present, but a brain is present,because it was not completely exposed to amniotic fluid. Such anevent is very rare. It may be part of craniofacial clefts associatedwith the limb-body wall complex, which results from early amniondisruption.
  52. 52. Congenital and pediatric neoplasms are uncommon. One type thatcan occur is a teratoma. Shown here is a large nasopharyngealteratoma that is protruding from the oral cavity.
  53. 53. The microscopic appearance of a teratoma is seen here. Thisneoplasm, though benign from a microscopic standpoint, canbecome a large mass that has severe consequences for a smallfetus, infant, or child. The three embryologic germ layers arerepresented by skin (ectoderm) at the top, cartilage (mesoderm) atthe bottom left center, and a colonic gland (endoderm) at the right.
  54. 54. There is a large mass involving the left upper arm and left chest ofthis fetus. This congenital neoplasm turned out to be alymphangioma.
  55. 55. Here is the microscopic appearance of the lymphangioma atmedium power, with large lymphatic spaces lined by a thinendothelium. The adjacent stroma has lymphoid nodules.Lymphangiomas in the pediatric age range tend to involve head,neck, and chest.
  56. 56. At high magnification, the histologically benign nature of thelymphangioma is apparent. There are enlarged lymphatic spaceslined by a thin endothelium. However, such lesions tend to be poorlycircumscribed and extend widely into surrounding soft tissues,making their surgical removal difficult.
  57. 57. Beneath the skin surface at the left are many dilated vascularchannels filled with many red blood cells. This is a neoplasm knownas a hemangioma.
  58. 58. This lobulated tan-white mass involving the kidney of a child is aWilms tumor. It manifests most often as an abdominal mass. Over90% of Wilms tumors are diagnosed during the first 6 years of life.About a fourth of cases are associated with hypertension.
  59. 59. Wilms tumor microscopically resembles the primitive nephrogeniczone of the fetal kidney, with primitive glomeruloid structures and acellular stroma. Wilms tumor is associated with mutations involvingthe WT1 tumor suppressor gene on chromosome 11. This neoplasmis very treatable with an excellent prognosis and >80% cure rateoverall.
  60. 60. This is the gross appearance of a neuroblastoma arising in the rightadrenal gland. It is the most common pediatric malignancy ininfancy, and 75% of cases are diagnosed in children less than 4years old. These tumors most often present as an abdominal ormediastinal mass.
  61. 61. Microscopically, neuroblastoma is a "small round blue cell" tumor.Histologic variations, as well as staging and cytogeneticcharacteristics help to determine the prognosis.
  62. 62. A rare neoplasm that appears most commonly in the first decade oflife is the rhabdomyosarcoma. This malignant neoplasm has skeletalmuscle derivation. The alveolar variant is shown here. Theseneoplasms occur most frequently in the head and neck area, as wellas the genitourinary tract.
  63. 63. This alveolar rhabdomyosarcoma is composed of primitive roundblue cells (rhabdomyoblasts) arranged in nests with spaces andsurrounded by a fibrous stroma. A variant of this neoplasm seen inthe genital tract is the sarcoma botryoides.
  64. 64. This is an example of a granulomatous process known as a"gumma" in a case of congenital syphilis. The gumma shown here islocated in the heart of a fetus. Syphilis can be acquired in utero inthe third trimester. Congenital syphilis is increasing in incidence inthe U.S.
  65. 65. Spirochetes are seen here. These are Treponema pallidumorganisms and are the causative agents for syphilis.
  66. 66. Here within the tubular epithelium of a fetal kidney can be seenmany large violet intranuclear inclusions characteristic cof congenitalcytomegalovirus (CMV) infection. The inclusions may appear in theurine of a liveborn infant with CMV.
  67. 67. The large pink inclusion in the erythroid precursor seen here in fetalspleen is evidence for parvovirus infection. Parvovirus, or "fifth"disease, produces a mild illness in children, marked by a "slappedcheek" facial rash. In adults, the illness often goes unnoticed, butpregnant women can pass the virus to the fetus, where it mayproduce marked fetal anemia and hydrops in some cases.
  68. 68. One of the most common forms of perinatal congenital infectionarises from bacterial agents that ascend the birth canal and may beseen in association with premature rupture of membranes (PROM)and acute chorioamnionitis. Seen here is a congenital pneumoniawith many neutrophils filling immature bronchioles.
  69. 69. This is hyaline membrane disease due to prematurity and lack ofsurfactant production from type II pneumonocytes within theimmature lung. Note the thick pink membranes lining the alveolarspaces.
  70. 70. A later complication of prematurity should the baby survive theimmediate neonatal period, during which time mechanical ventilationwas necessary, is bronchopulmonary dysplasia (BPD). With BPD,there is interstitial fibrosis and inadequate alveolar developmentfor good pulmonary function. Respiratory distress can continue formonths to years.
  71. 71. The dense layer of small dark blue cells seen here below theependyma of the lateral ventricle is the germinal matrix. Thegerminal matrix is a highly cellular and highly vascularized regionfrom which cells migrate out during brain development, mainlybetween 22 and 30 weeks gestation. This area is highly vulnerableto birth injury and changes in blood pressure following birth. Ifsevere and if survival occurs, the hemorrhage may organize andlead to obstructive hydrocephalus. A germinal matrix hemorrhageis shown below.
  72. 72. This coronal section of a premature neonatal brain showsintraventricular hemorrhage (IVH) extending from a germinalmatrix hemorrhage. Such hemorrhages occur from a variety offactors that afflict neonates, including difficulty regulating bloodpressure. Such hemorrhages can be devastating.
  73. 73. Intraventricular hemorrhage (IVH) can be minimal, but can also besevere as shown here with blood filling and distending all of thelateral ventricles, extending into brain parenchyma, and extendingdown the third ventricle and out into the subarachnoid space. Theprognosis is grim.
  74. 74. The yellow staining in the brain of a neonate is known askernicterus. There is a coronal section of medulla on the left andcerebral hemisphere on the right demonstrating kernicterus in deepgrey matter of hemisphere and brain stem. Increased unconjugatedbilirubin, which accounts for the kernicterus, is toxic to the braintissue. Kernicterus is more likely to occur with prematurity, low birthweight, and increased bilirubin levels. [Image contributed byJeannette J. Townsend, MD, University of Utah]
  75. 75. A complication of prematurity and low birth weight is neonatalnecrotizing enterocolitis (NEC) in which ischemia results in focal toconfluent areas of bowel necrosis, most often in the terminal ileum.Seen at autopsy here is a dark red appearance to the small intestineof a premature neonate. [Image contributed by Ted Pysher, MD,University of Utah]
  76. 76. The clinical manifestations of neonatal necrotizing enterocolitis (NEC) inpremature neonates include abdominal distension, ileus, and bloodystool at several days of age. Compared to normal bowel at the left,bowel involved by NEC at the right shows hemorrhagic necrosis,beginning in the mucosa and extending to involve the muscular wall,with the potential for perforation.
  77. 77. This is pyloric stenosis. Note the prominent hypertrophied musclewith elongation and narrowing of the pylorus at the gastric outlet onthe left. Pyloric stenosis is uncommon, but is a cause for "projectile"vomiting in an infant about 3 to 6 weeks of age. Males are affectedmore than females. The overall incidence is approximately 3 per1000 livebirths.The "pacemaker" interstitial cells of Cajal (ICC) regulate motility, andcontain the enzyme heme oxygenase-2 which generates carbonmonoxide (CO) as a neurotransmitter to cause relaxation in adjacentsmooth muscle cells. The lack of ICCs in pyloric stenosis results indeficient CO production leading to motility dysfunction.
  78. 78. Meconium ileus is most often seen in the first few days of life inneonates with cystic fibrosis, but can rarely occur in infants with anormal pancreas. In cystic fibrosis, the abnormal pancreaticsecretions lead to inspissated meconium that produces intestinalobstruction. The dilated coils of ileum are opened here to reveal theinspissated green meconium (which may also be tarry or gritty),while the unopened colon at the upper left and the appendix at thelower left beyond the ileocecal valve are not dilated, and little or nomeconium is passed per rectum. [Image contributed by Ted Pysher,MD, University of Utah]
  79. 79. Meconium peritonitis shown here as a greenish exudate overlyingthe serosal surfaces of the peritoneal cavity can complicatemeconium ileus in utero, particularly in fetuses with cystic fibrosis.The bowel ruptures and leaks meconium, which produces achemical peritonitis. Calcifications in the spilled meconium may beseen radiographically. Another complication of meconium ileus isvolvulus. [Image contributed by Ted Pysher, MD, University of Utah]
  80. 80. Shown here is dilation of bowel (megacolon) proximal to the affectedregion of narrowing at the lower left center in sigmoid colon. Mucosaldamage and secondary infection may follow.Hirschsprung disease results from an absence of ganglion cells inboth submucosal and myenteric plexuses and can occur in either asegment of colon (short segment disease) or the entire colon (longsegment disease). The aganglionic segment becomes narrowed,causing obstruction, with proximal dilation. Affected newborns maydevelop focal inflammation at the point of obstruction, with fever anddiarrhea. Colonic perforation may occur. Infants with the diseasemay have alternating diarrhea and constipation, while childrenmainly have constipation. Treatment consists of surgical correctionwith resection of the aganglionic segment.Hirschsprung disease is thought to result from mutation ofsusceptible genes interacting with environmental and other factors,resulting in variable penetrance. Multiple genetic mutations havebeen found, but about half of familial cases and 15% of sporadiccases are associated with RET gene mutations that inactivate RETreceptor kinase activity. RET promotes survival and growth ofneurites and provides direction to migrating neural crest cells. Theincidence of Hirschsprung disease is 1 in 5000 livebirths. It has a 4:1
  81. 81. male to female predominance. Short segment disease is morecommon in males, while the rarer long segment diseasepredominates in females.
  82. 82. Pneumatosis intestinalis is a rare finding in which gas-filled cystsappear in submucosa. It may complicate necrotizing enterocolitis, asin this case. The gas may dissect into submucosa or may begenerated by bacteria.
  83. 83. The skin is soft and the hair is fine in a normal newborn, as seenhere.
  84. 84. The accessory spleens seen here at the hilum of the normal-sizedspleen are not uncommon and by themselves have no significance.
  85. 85. There are few changes indicative of postmaturity (gestation beyond42 weeks). Here are long fingernails that can be seen withpostmaturity.
  86. 86. Death of the fetus in utero is accompanied by changes ofmaceration. Seen here is one of the earliest changes (within half aday) which is slippage of the skin. As this process advances, theskin becomes reddened.
  87. 87. The normal fetal chest at term is shown here. The thymus is a largestructure with the important job of developing the cell-mediatedimmune system with T-cells. The right lung, heart, diaphragm, andliver are seen here as well.
  88. 88. Stress from a variety of illnesses in the fetus and neonate may bemanifested with thymic involution. One of the earliest changes seenis an increase in cortical macrophages, typical in 1 to 2 daysfollowing the onset of illness. Note the "starry sky" appearances herefrom increased macrophages.
  89. 89. The neonatal scalp is reflected at autopsy to reveal dark red bloodbeneath the galea aponeurotica (dense connective tissue of scalp)and over the cranium. This is subgaleal hemorrhage and it is fairlycommon during the birth process.
  90. 90. Meconium spillage is a complication seen at or near term, typicallywhen there is fetal distress with loss of anal sphincter tone andpassage of meconium into amniotic fluid. A clue to this occurrence isgreenish staining of fetal skin or fetal surface of the placenta. Theworst consequence of meconium spillage is meconium aspirationinto the lungs. Fetal distress also leads to reflex gasping efforts bythe baby, with the result that the meconium in the amniotic cavity isaspirated into the lungs. Rugby ball shaped balls of meconium aswell as numerous "squames" from fetal skin are seen here.
  91. 91. In this case of meconium aspiration, small rounded balls ofmeconium are seen in an alveolus, along with flattened "squames"or desquamated fetal skin cells that are found in the amnionic fluid.Meconium is an irritant that leads to respiratory distress. At birth,tracheal suction and lung lavage may be useful to help remove themeconium.