GASTROINTESTINAL PATHOLOGY

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CHAPTER 14 GASTROINTESTINAL PATHOLOGY

Hypertrophic pyloric stenosis

Gastric volvulus

Graft-versus-host disease

Spontaneous perforation of the GI tract

Colon

Chronic inflammatory bowel disease

Fibrosing colonopathy

Miscellaneous GI specimens

Anorectal anomalies

Currarino triad

Vermiform appendix

Acute appendicitis

Persistent hyperinsulinemic hypoglycemia of infancy

INTRODUCTION

• Specimens from the gastrointestinal tract comprise a significant proportion of the workload of many pediatric surgical pathology departments

number is increasing with advances in endoscopic techniques

• Complexity of GI disease is increasing since

newer forms of treatment becoming available which may alter classical histological appearances

– such as monoclonal anti-inflammatory antibodies

newer forms of treatment for non-GI disease may also cause changes in the GI tract

GI involvement in diseases previously not suspected to have GI pathology

– such as enteropathy in Shwachmann–Diamond syndrome

• Entities provided in this chapter are primarily those seen with reasonable frequency as surgical pathology specimens

most organized by main site of involvement

– some entities may affect multiple sites but are documented according to the usual site of disease

ESOPHAGUS

ESOPHAGEAL ATRESIA AND TRACHEO-ESOPHAGEAL FISTULA

• 1 : 3000–5000

• Associated maternal polyhydramnios (50%)

• Around half of cases preterm with associated abnormalities

cardiac defects

imperforate anus

duodenal atresia

Histopathological features (Dutta, Mathur, Bhatnagar 2000)

• Unusual to get surgical specimen

• When submitted tissue comprises elements of tracheal and esophageal wall in variable combinations according to case (Figs 14.2, 14.3)

Fig 14.2 One-day-old girl with esophageal atresia and tracheo-esophageal fistula. The specimen is the tip of the proximal esophageal pouch. Photomicrograph of the specimen demonstrating the pouch comprising the usual elements of esophageal wall. The mucosa shows some ciliated epithelium. Unusually, no striated muscle was present in the muscular coat.

Fig 14.3 One-year-old girl with previous EA repair. Stricture below anastomosis excised. Photomicrograph of the excised piece of esophagus with thickened and disorganized muscle coat and containing bronchial type glands extending deeply into the muscle coat.

DUPLICATION CYSTS

• Developmental defects

can affect any site in the GI tract from esophagus to rectum

• Variable size

• Tubal or spherical

• Mass effects or incidental

may be associated with vertebral defects

may communicate with spinal canal

– neuroenteric cyst

• Present with

respiratory distress

feeding difficulty

Histopathological features

• Two layered muscularis propria

• Variable gastrointestinal mucosal lining type (Figs 14.4, 14.5)

Fig 14.4 Nine-month-old boy. Antenatal diagnosis of thoracic cyst. Posterior mediastinal cyst (3.5 × 3 × 2.5 cm) attached to wall of esophagus beneath the right vagus nerve with a fibrous attachment to the vertebral body. It contained clear fluid. Photomicrograph of the cyst wall demonstrating double muscle layer lined by simple gastric cardiac type mucosa. Focally there was ulceration.

Fig 14.5 Three-year-old boy with an incidental finding of a para-esophageal cyst (1.7 × 1 × 1 cm) during fundoplication. Photomicrograph of the cyst wall showing a smooth muscle coat with a lining of ciliated columnar epithelium. There is no cartilage – an important point of distinction from a bronchogenic cyst.

ESOPHAGEAL DIVERTICULUM

• Congenital diverticula very rare

• Most are acquired

• Histologically consist of all layers of esophageal wall

ACHALASIA

• See below under motility disorders

GASTRO-ESOPHAGEAL REFLUX DISEASE

• Some degree of gastro-esophageal reflux (GER) nearly universal in children

• GER of sufficient severity to cause symptoms or disease is termed gastro-esophageal reflux disease (GERD)

• Common in infants and children

• Most common under 6 months of age

• Presents with

feeding difficulties

failure to thrive

respiratory symptoms

• Many mild cases treated without endoscopy

• Endoscopy and biopsy

• pH monitoring in difficult cases and differentiation from primary eosinophilic esophagitis

Histopathological features

• Changes can be patchy

most severe in distal esophagus

multiple biopsies required

• Basal cell hyperplasia (Fig 14.6)

• Intercellular edema

• Elongation of connective tissue papillae

• Congestion of capillaries

• Increased numbers of intraepithelial

mononuclear inflammatory cells (’squiggle’ cells)

neutrophil polymorphs (unusual)

– if numerous consider fungal disease also

• Ulceration uncommon

• Non-specific stromal inflammation

Fig 14.6 Reflux esophagitis. Eight-year-old boy with short gut, on parenteral nutrition. Biopsy close to gastro-esophageal junction. Photomicrograph of esophageal biopsy showing basal cell hyperplasia with elongation of the connective tissue papillae that demonstrate vascular engorgement and perivascular hemorrhage, intercellular edema and an infiltrate within the epithelium of lymphocytes and eosinophils. The infiltrate is confined largely to the epithelium around the connective tissue papillae.

Differential diagnosis

• Eosinophilic esophagitis

• Infectious esophagitis

• Drug and chemical injury

• Crohn’s disease

COLUMNAR EPITHELIAL LINED ESOPHAGUS (CELE)

• Columnar epithelium replaces normal squamous epithelial covering of lower esophagus

metaplastic process

• Irregular junction with squamous lined esophagus

• Requires certainty regarding exact site of biopsy

• Usually gastric cardiac type in children

• Barrett’s esophagus defined as CELE with goblet cells

• Barrett’s esophagus very uncommon in children

• More common in

cases with severe longstanding GERD

cases following TEF repair

cystic fibrosis

EOSINOPHILIC ESOPHAGITIS

• Relatively common in children (Furuta et al 2007)

• Frequently associated with allergic disease

• Normal pH studies

• Symptoms include

food intolerance

food ‘sticking’

• May have upper airway diseases such as

laryngeal edema

subglottic stenosis

• Diagnosis based on histological appearance in the correct clinical context

not on histology alone

• Corrugated mucosa on endoscopy

• Do not respond to anti-reflux treatment

• Complications

Differential diagnosis and diagnostic pitfalls

requires clinicopathological correlation

INFECTIVE ESOPHAGITIS

• Almost always in the setting of immunocompromise

• In severely immunocompromised infections with multiple organisms occur

CROHN’S DISEASE OF THE ESOPHAGUS

• Esophageal involvement relatively common

can occur in isolation

• Usually lymphocytic esophagitis with (Fig 14.11)

basal cell hyperplasia

intercellular edema

infiltration of epithelium by mononuclear cells

• May have well formed non-caseating epithelioid granulomas in lamina propria beneath epithelium (Fig 14.12)

• May be ulceration or stricture

Fig 14.11 Lymphocytic esophagitis in Crohn’s disease. Aphthous ulcers in duodenum and colon. Macroscopically normal ileum but granulomatous inflammation on biopsy. Photomicrograph of esophagus shows mild lymphocytic esophagitis with increased numbers of intraepithelial mononuclear cells associated with mild basal cell hyperplasia and intercellular edema. This appearance is very common in Crohn’s disease but is not specific.

Fig 14.12 Sixteen-year-old boy with Crohn’s disease treated with Infliximab. Stricture of esophagitis noted on endoscopy. Granulomas present in esophagus, stomach, ileum and colon. Photomicrograph of esophageal biopsy showing epithelial hyperplasia with a well formed epithelioid granuloma in the lamina propria immediately beneath the epithelium. A multinucleated giant cell is present. There is a scattering of lymphocytes in the surrounding connective tissue.

CHEMICAL AND DRUG-INDUCED ESOPHAGITIS

• Accidental swallowing of corrosive liquids in children

• Initial tissue necrosis edema and inflammation followed by repair with stricture formation (Figs 14.13, 14.14)

• Drug-induced inflammation tends to occur

in the middle one-third

at the site of strictures or other narrowings

• Not uncommon with high dose chemotherapy

• Superficial erosion

• Non-specific lymphocytic esophagitis

• May follow ingestion of iron containing medicines (Abraham 1999)

crystalline iron deposition in the tissue

• May also occur in stomach and duodenum (Figs 14.15, 14.16)

Fig 14.13 Caustic stricture of the esophagus from a 7-year-old boy. A tubular segment of esophagus cut longitudinally to demonstrate the severe fibrous thickening of the wall with occlusion of the lumen. The lumen is visible on the left hand side of the picture. The muscle coat visible as a slightly glistening darker layer on the left of the picture is replaced by white fibrous tissue on the right.

Fig 14.14 Caustic stricture of the esophagus. Photomicrograph showing intense hyperplasia of the epithelium. The underlying tissue consists of dense collagenous fibrous tissue with obliteration of muscle.

Fig 14.15 Photomicrograph of gastric mucosa showing crystalline iron deposition in gastric mucosa, evident as brown refractile material both on the surface and within the superficial lamina propria.

Fig 14.16 Same case as previous showing positive Perls’ reaction in the surface iron (to the right of the picture).

STOMACH

• Endoscopic biopsies for assessment of gastritis by far the most common gastric specimen for pediatric surgical pathologists

• Other entities such as Menetrier’s disease, dysplasia, GAVE and many other specific histological lesions seen in adults are exceptionally uncommon in children and are not described here

see standard adult texts

GASTRITIS

• An important cause of abdominal pain in children

• Several different types

• Non-specific gastric changes may also be seen in a range of pediatric enteropathies

see small intestine section for diagnostic features

• Any severely ill patient may also show non-specific acute gastritis

clinically appears to be less common than adults

Helicobacter pylori gastritis

• Common in children but unusual in tertiary level practice as most detected and treated locally

• May not be apparent endoscopically

• H. heilmanni in minority

organism is longer with tighter spiral (Qualia et al 2007)

Fig 14.17 Helicobacter gastritis. Giemsa stained preparation at high power showing the organisms in the surface mucus. The organisms can be seen on H&E but are much more evident in the Giemsa preparations. They are confined to the mucus of the surface and the pits.

Fig 14.18 Helicobacter gastritis. Photomicrograph of a high power view of the lamina propria. Although neutrophil polymorphs are present, they are not as prominent as in adult patients with Helicobacter gastritis.

Fig 14.19 Helicobacter gastritis. Low power photomicrograph of gastric antral mucosal biopsy showing a diffuse inflammatory cell infiltrate in the lamina propria with lymphoid follicle and germinal center. The presence of germinal centers should always prompt a careful search for Helicobacter. They were present in this case.

Lymphocytic gastritis

• Lymphocytic infiltrate in surface and crypt epithelium

>20 lymphocytes / 100 surface epithelial cells (Fig 14.21)

• Association with untreated celiac disease

More frequent in younger patients

Often associated with vomiting

Resolves with gluten-free diet

• Not all cases associated with gluten-enteropathy

minority of HLO-associated gastritis

minority of Crohn’s gastritis

other autoimmune disease

some apparently isolated

• Collagenous gastritis may be an associated entity

subsurface epithelial band of collagenous ‘fibrosis’

Fig 14.21 Celiac disease with lymphocytic gastritis. Photomicrograph of a gastric biopsy from a case of celiac disease showing increased numbers of intraepithelial lymphocytes in both surface and glandular epithelium, akin to the appearance in the duodenum. Such patients tend to have vomiting as a symptom of their disease.

Autoimmune gastritis

• Relatively uncommon in children

• Usually associated with autoimmune enteropathy and/or other autoimmune disease

• Histological features variable

non-specific inactive gastritis

active gastritis

relative neuroendocrine cell hyperplasia

HYPERTROPHIC PYLORIC STENOSIS

• See below under motility disorders

GASTRIC VOLVULUS

• Very rare in children

• Can be associated with apslenia

• Unusual to receive surgical specimens from such cases

non-specific secondary features

GRAFT-VERSUS-HOST DISEASE

• See specific section below

GASTRIC TUMORS

• Very rare in childhood

• Gastric carcinoma almost never occurs

• Stromal tumors may occur

see specific section below

• Polyps rare

see small intestine

SPONTANEOUS PERFORATION OF THE GI TRACT

• In this context means isolated perforation with no other detectable underlying disease process

does not include those with demonstrable acute ischemia, necrotizing enterocolitis (NEC), etc

• Reported more in low birth weight infants

even those without NEC

• Probably ischemic in nature

• Usually gastric

can affect colon, Meckel’s diverticulum

• May be associated with congenital focal defective musculature

• May rarely be associated with underlying genetic condition

Ehlers–Danlos syndrome

Histopathological features

• Non-specific features secondary to perforation (Fig 14.22)

• No detectable underlying cause such as acute ischemia

• Other causes such as vasculitis etc must always be excluded

Fig 14.22 Spontaneous perforation of the stomach. Photomicrograph from the edge of the perforation showing hemorrhagic necrosis of the tissues. This is a non-specific appearance of ischemic-type damage.

SMALL INTESTINE

INTESTINAL ATRESIA

• Intrauterine process resulting in incomplete bowel lumen

• Duodenal atresia

presumed developmental

mainly associated with trisomy 21

rarely submitted for pathological assessment

– usually treated with duodenoduodenostomy

• Intestinal atresia

presumed due to intrauterine insult

ischemic / hypotensive episode

jejunum and ileum affected

isolated or multiple

more commonly submitted

– treated with resection and anastomosis

Histopathological features

• Intestinal atresia

discontinuous lumen

atretic segment (Fig 14.23)

fibrosis (Fig 14.24)

– focal muscularis replacement (Fig 14.25)

dystrophic calcification

pigment-laden macrophages

Fig 14.23 Ileal atresia. Resected specimen showing a thread-like segment of stenotic bowel with a more proximal part with intense dilatation because of the obstruction.

Fig 14.24 Ileal atresia. Photomicrograph showing the junction of atretic and patent segment of intestine. The bowel ends blindly with fusion of all the layers into a fibrovascular band without recognizable bowel wall structures. Hemosiderin is frequently present at such sites indicating previous hemorrhage.

Fig 14.25 Stenosis of bowel following in-utero ischemia. Photomicrograph demonstrating the thickened submucosa with focal fresh hemorrhage. The muscularis mucosae is largely absent – a sign of previous ulceration. The muscular coat is also focally deficient.

MECKEL’S DIVERTICULUM

• 1–4% of population

• May be completely asymptomatic

Histopathological features

• Antimesenteric border of terminal ileum approx 30cm from ileo-cecal (IC) valve

• Up to about 8cm long (Fig 14.26)

• May be long and tubular or squat and almost cystic

• Tip may be bifid or nodular

• All components of normal bowel wall present

• Muscle coat may be very attenuated at the tip or distorted by heterotopic tissue

• Lined usually by

may have gastric body mucosa lining in minority (Fig 14.27)

– Helicobacter may colonize

rarely colonic tissue

• May see ulceration or bleeding point

• May have nodules of pancreatic tissue (including islets) in wall (Fig 14.27)

• Serosa may show fibrosis or inflammation

Fig 14.26 Meckel’s diverticulum. Photograph demonstrating the excised specimen of piece of ileum with the diverticulum arising from its antimesenteric border, being long and tubular with slightly bulbous end.

Fig 14.27 Meckel’s diverticulum. Photomicrograph showing gastric body mucosa lining the distal part of the diverticulum. In the submucosa there is a nodule of heterotopic pancreatic tissue.

INTUSSUSCEPTION

• Invagination of bowel into the bowel distal to it

• Mainly ileocecal

• Mainly (>90%) infants

when occurring in other ages or at other sites more likely to be secondary to another specific pathology

• Results in secondary ischemic damage to bowel

• Presents with

’red-currant jelly’ stool

palpable abdominal mass

• Many cases can be reduced medically

only those not responding come to surgery and resection

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