DISEASES OF THE DISEASES OF THE

SMALL & LARGE INTESTINESSMALL & LARGE INTESTINES Developmental anomaliesDevelopmental anomalies

– Atresia, stenosis, MeckelAtresia, stenosis, Meckel’’s diverticulum, s diverticulum, malrotationmalrotation

– HirschsprungHirschsprung’’s diseases disease Vascular disordersVascular disorders Inflammatory & diarrheal diseasesInflammatory & diarrheal diseases

– Enterocolitis, malabsorptionEnterocolitis, malabsorption syndromes syndromes Idiopathic inflammatory bowel diseasesIdiopathic inflammatory bowel diseases

– CrohnCrohn’’s disease, ulcerative colitiss disease, ulcerative colitis Colonic diverticular diseasesColonic diverticular diseases TumorsTumors

PATHOLOGY OF THE SMALL INTESTINEPATHOLOGY OF THE SMALL INTESTINE

DEVELOPMENTAL ANOMALIESDEVELOPMENTAL ANOMALIES Atresia Atresia or or stenosisstenosis: involving a segment of bowel: involving a segment of bowel DuplicationDuplication: well-formed saccular structure which may : well-formed saccular structure which may

or may not communicate with bowel lumenor may not communicate with bowel lumen MeckelMeckel’’s diverticulums diverticulum:most common, benign anomaly:most common, benign anomaly– Failure of involution of the omphalomesenteric ductFailure of involution of the omphalomesenteric duct– Blind-ended tubular protrusion, <6 cm in lengthBlind-ended tubular protrusion, <6 cm in length– In ileum, within 2 feet of cecumIn ileum, within 2 feet of cecum– Heterotopic gastric mucosa in 1/2 of cases (c/o Heterotopic gastric mucosa in 1/2 of cases (c/o

bleeding & pain); rarely heterotopic pancreatic restsbleeding & pain); rarely heterotopic pancreatic rests OmphaloceleOmphalocele: defect in periumbilical abdominal wall, : defect in periumbilical abdominal wall,

resulting in a membranous sac; +/- intestinal herniationresulting in a membranous sac; +/- intestinal herniation

                                           

DEVELOPMENTAL ANOMALIES OF THE LARGE INTESTINEDEVELOPMENTAL ANOMALIES OF THE LARGE INTESTINE

MALROTATIONMALROTATION The developing cecum fails to descend to its The developing cecum fails to descend to its

definitive adult position in the right lower definitive adult position in the right lower quadrant. The cecum may be found anywhere in quadrant. The cecum may be found anywhere in the abdomen. the abdomen.

Clinical features:Clinical features:– May be asymptomaticMay be asymptomatic– May cause clinical problems: volvulus May cause clinical problems: volvulus

Diagnosis of acute appendicitis may be a problemDiagnosis of acute appendicitis may be a problem

DEVELOPMENTAL ANOMALIES OF THE LARGE INTESTINEDEVELOPMENTAL ANOMALIES OF THE LARGE INTESTINE

HIRSCHSPRUNG’S DISEASEHIRSCHSPRUNG’S DISEASE aka: congenital megacolonaka: congenital megacolon Failure of development of MeissnerFailure of development of Meissner’’s & s &

AuerbachAuerbach’’s plexuses due to arrest in migration of s plexuses due to arrest in migration of neural crest-derived cells along GITneural crest-derived cells along GIT

Ganglion cells are lacking at anorectal junction & Ganglion cells are lacking at anorectal junction & distal colon, causing functional obstruction and distal colon, causing functional obstruction and progressive distension (megacolon) of the progressive distension (megacolon) of the innervated colon proximal to the affected segmentinnervated colon proximal to the affected segment

In 20% of patients, a longer segment is In 20% of patients, a longer segment is aganglionicaganglionic

Patients: 1 in 5000-8000 live births; M:F=4:1Patients: 1 in 5000-8000 live births; M:F=4:1 Associated with other congenital anomalies: Associated with other congenital anomalies:

hydrocephalus, VSD, Meckelhydrocephalus, VSD, Meckel’’s diverticulums diverticulum

HIRSCHSPRUNG DISEASEHIRSCHSPRUNG DISEASE

PATHOLOGY & CLINICAL FEATURES OFPATHOLOGY & CLINICAL FEATURES OF

HIRSCHSPRUNG’S DISEASEHIRSCHSPRUNG’S DISEASE Pathology: Lack of ganglion cells in muscularis & Pathology: Lack of ganglion cells in muscularis &

submucosa of affected (nondistended) distal submucosa of affected (nondistended) distal segment; unaffected proximal segment will be segment; unaffected proximal segment will be dilated, with thin wall (occasionally thick) & possible dilated, with thin wall (occasionally thick) & possible stercoral ulcersstercoral ulcers

Clinical symptoms: Delayed passage of meconium, Clinical symptoms: Delayed passage of meconium, vomiting in 48-72 hrs and obstructive constipationvomiting in 48-72 hrs and obstructive constipation

Complications: enterocolitis, fluid & electrolytes Complications: enterocolitis, fluid & electrolytes disturbancesdisturbances

Dx: full thickness biopsy of nondistended bowel Dx: full thickness biopsy of nondistended bowel segmentsegment

Rx: surgicalRx: surgical

PATHOLOGY OF SMALL & LARGE INTESTINEPATHOLOGY OF SMALL & LARGE INTESTINE

DIARRHEAL DISORDERSDIARRHEAL DISORDERS Diarrhea= increase in stool mass, frequency or fluidityDiarrhea= increase in stool mass, frequency or fluidity Daily stool production>250 gm, containing 70-95% waterDaily stool production>250 gm, containing 70-95% water Dysentery= low volume painful bloody diarrheaDysentery= low volume painful bloody diarrhea Classification of diarrheal disorders:Classification of diarrheal disorders:– Secretory diarrhea: direct or enterotoxin-mediated Secretory diarrhea: direct or enterotoxin-mediated

damage to surface epitheliumdamage to surface epithelium– Osmotic diarrhea: osmotic forces of luminal solutesOsmotic diarrhea: osmotic forces of luminal solutes– Exudative diarrhea: destruction of epithelial layerExudative diarrhea: destruction of epithelial layer– Malabsorption: unabsorbed nutrients & fatMalabsorption: unabsorbed nutrients & fat– Deranged motitlity: decreased intestinal retention Deranged motitlity: decreased intestinal retention

time; decreased motilitytime; decreased motility

DIARRHEAL DISEASEDIARRHEAL DISEASE

MALABSORPTMALABSORPTION SYNDROMESION SYNDROMES Suboptimal absorption of different nutrients, electrolytes Suboptimal absorption of different nutrients, electrolytes

&/or water as a result of disturbance in intraluminal &/or water as a result of disturbance in intraluminal digestion, absorption, terminal (brush border) digestion &/or digestion, absorption, terminal (brush border) digestion &/or transepithelial transport.transepithelial transport.

Digestion of food occurs mostly in stomach & small Digestion of food occurs mostly in stomach & small intestine, while absorption occurs mostly in duodenum & intestine, while absorption occurs mostly in duodenum & jejunumjejunum

Malabsorption may be caused by a variety of diseasesMalabsorption may be caused by a variety of diseases Small intestinal biopsy is an important diagnostic tool: may Small intestinal biopsy is an important diagnostic tool: may

show characteristic findings, normal or nonspecific changesshow characteristic findings, normal or nonspecific changes c/o weight loss, anorexia, abdominal distension, muscle c/o weight loss, anorexia, abdominal distension, muscle

wasting and passage of abnormally bulky, frothy, greasy, wasting and passage of abnormally bulky, frothy, greasy, yellow or gray stools (steatorrhea)yellow or gray stools (steatorrhea)

CONSEQUENCES OFCONSEQUENCES OF

MALABSORPTMALABSORPTION SYNDROMESION SYNDROMES Anemia: iron, pyridoxine, folate or vit. B12 deficiencyAnemia: iron, pyridoxine, folate or vit. B12 deficiency Bleeding: vitamin K deficiencyBleeding: vitamin K deficiency Osteopenia & tetany: Ca, Mg, vitamin D deficiencyOsteopenia & tetany: Ca, Mg, vitamin D deficiency Amenorrhea, impotence, infertitlity: generalized Amenorrhea, impotence, infertitlity: generalized

malnutritionmalnutrition Hyperparathyroidism: Ca & vitamin D deficiencyHyperparathyroidism: Ca & vitamin D deficiency Purpura & petechiae: vitamin Purpura & petechiae: vitamin KK deficiency deficiency Edema: protein deficiencyEdema: protein deficiency Dermatitis & hyperkeratosis: vit A, Zn, eFA, niacinDermatitis & hyperkeratosis: vit A, Zn, eFA, niacin Mucositis: vitamin deficienciesMucositis: vitamin deficiencies Peripheral neuropathy: vit A & B12 deficiencyPeripheral neuropathy: vit A & B12 deficiency

CLASSIFICATION OFCLASSIFICATION OF

MALABSORPTMALABSORPTION SYNDROMESION SYNDROMES Defective intraluminal digestion: pancreatic Defective intraluminal digestion: pancreatic

insufficiency; Z-E syndrome; defective bile secretion insufficiency; Z-E syndrome; defective bile secretion due to biliary obstruction, hepatic or ileal dysfunction; due to biliary obstruction, hepatic or ileal dysfunction; bacterial overgrowthbacterial overgrowth

Mucosal cell abnormalities: lactose intolerence, Mucosal cell abnormalities: lactose intolerence, bacterial overgrowth, abetalipoproteinemiabacterial overgrowth, abetalipoproteinemia

Reduced small intestine surface: Celiac sprue, CrohnReduced small intestine surface: Celiac sprue, Crohn’’s s ,short ,short ––gut syndromegut syndrome

Lymphatic obstruction: lymphoma, tuberculosisLymphatic obstruction: lymphoma, tuberculosis Infection: enteritis, tropical sprue, WhippleInfection: enteritis, tropical sprue, Whipple’’s diseases disease Iatrogenic: surgeries, drug inducedIatrogenic: surgeries, drug induced