Gastrointestinal Pathology and Embryology Vocabulary

Vocabulary flashcards covering core concepts, anatomical structures, embryological anomalies, and clinical pathologies of the gastrointestinal system.

Intestinal Malrotation

A developmental anomaly where improper midgut rotation leads to abnormal positioning of the bowel (such as the cecum in the RUQ), predisposing to intestinal obstruction via adhesive Ladd bands or midgut volvulus.

Duodenal Atresia

Congenital failure of the duodenum to recanalize, characterized by bilious vomiting within the first 1-2 days of life, a double bubble sign on abdominal X-ray, and a strong association with Down syndrome.

Apple Peel Atresia

Jejunal or ileal atresia caused by an in utero vascular accident (occlusion of the SMA), resulting in a blind-ended proximal jejunum and a distal segment wound around a thin vascular stalk.

Hypertrophic Pyloric Stenosis

Congenital hypertrophy of the pylorus leading to gastric outlet obstruction, presenting in 2-6-week-old infants with nonbilious projectile vomiting, an olive-shaped epigastric mass, and hypokalemic hypochloremic metabolic alkalosis.

Annular Pancreas

Developmental malformation caused by abnormal rotation of the ventral pancreatic bud, forming a ring of pancreatic tissue that encircles the second part of the duodenum and may cause duodenal obstruction.

Pancreas Divisum

Common congenital anomaly where the ventral and dorsal pancreatic buds fail to fuse at 8 weeks of embryonic development, causing the accessory duct to drain the majority of the pancreas.

Meckel Diverticulum

The most common vitelline duct anomaly, resulting from partial closure of the omphalomesenteric duct; a true diverticulum that frequently contains ectopic gastric or pancreatic tissue and follows the rule of 2s.

Hirschsprung Disease

Congenital bowel motility disorder caused by failure of neural crest cells to migrate caudally, resulting in an aganglionic, unrelaxing intestinal segment (always involving the rectum) and proximal compensatory dilation.

Pringle Maneuver

Surgical technique used to control hepatic bleeding by compressing the hepatoduodenal ligament, which contains the portal triad (proper hepatic artery, portal vein, and common bile duct).

Brunner Glands

Compound tubular submucosal glands located in the duodenum (most dense at the pylorus) that secrete bicarbonate-rich ($\text{HCO}_3^-$) alkaline mucus to neutralize acidic gastric chyme.

Paneth Cells

Specialized secretory cells found at the base of intestinal crypts of Lieberkühn that provide innate immune defense against microorganisms by releasing lysozyme and defensins.

Achalasia

Esophageal motility disorder characterized by impaired lower esophageal sphincter (LES) relaxation and absent peristalsis due to loss of myenteric (Auerbach) plexus inhibitory neurons; shows a bird's beak sign on barium swallow.

Zenker Diverticulum

False diverticulum formed by mucosal herniation in the posterior hypopharynx through Killian triangle, caused by impaired cricopharyngeal muscle relaxation during swallowing.

Mallory-Weiss Tear

Longitudinal mucosal lacerations at the gastroesophageal junction resulting from severe, repetitive vomiting, typically presenting as painful hematemesis in patients with alcoholism or bulimia.

Boerhaave Syndrome

Transmural rupture of the distal esophagus caused by violent retching, presenting as a surgical emergency with pneumomediastinum and a crunching heart sound (Hamman sign).

Barrett Esophagus

Specialized intestinal metaplasia of the distal esophagus where nonkeratinized stratified squamous epithelium is replaced by nonciliated columnar cells with goblet cells, arising from chronic GERD and predisposing to esophageal adenocarcinoma.

Ménétrier Disease

Precancerous hypertrophic gastropathy caused by overproduction of TGF-$\alpha$, leading to massive gastric mucosal fold enlargement, excess mucus production, parietal cell atrophy, and protein-losing enteropathy.

Zollinger-Ellison Syndrome

Gastrinoma of the pancreas or duodenum secreting excess gastrin, leading to parietal cell hyperplasia, severe peptic ulcer disease (often refractory or in atypical locations), and diarrhea.

Whipple Disease

Systemic infection caused by Tropheryma whipplei, marked by periodic acid-Schiff (PAS)-positive foamy macrophages in the intestinal lamina propria, arthralgias, cardiac abnormalities, and neurologic symptoms.

Abetalipoproteinemia

Autosomal recessive disorder caused by loss-of-function mutations in the MTP gene, leading to inability to synthesize apolipoprotein B, absence of chylomicrons and VLDL, and lipid accumulation in enterocytes with foamy cytoplasm.

Crohn Disease

Chronic transmural inflammatory bowel disease that can affect any segment of the GI tract with skip lesions, cobblestone mucosa, creeping fat, noncaseating granulomas, and perianal fistulas.

Ulcerative Colitis

Chronic mucosal and submucosal inflammatory bowel disease restricted to the colon, starting in the rectum and extending continuously proximally, characterized by crypt abscesses, bloody diarrhea, and lead pipe appearance on imaging.

Toxic Megacolon

Severe, acute, life-threatening dilation of the colon ($>5.5\,cm$) due to neuromuscular degeneration in fulminant colitis; presents with abdominal pain, distension, fever, and shock.

Necrotizing Enterocolitis

Gastrointestinal emergency in premature infants initiated by enteral feeding, where bacterial invasion of immature bowel walls leads to ischemic necrosis and pneumatosis intestinalis (air in the bowel wall).

Lynch Syndrome

Autosomal dominant condition caused by mutations in DNA mismatch repair genes (e.g., MLH1, MSH2), leading to microsatellite instability and early-onset, predominantly right-sided colorectal cancer.

Carcinoid Syndrome

Clinical syndrome caused by metastatic neuroendocrine tumors secreting serotonin (5-HT), presenting with episodic cutaneous flushing, watery diarrhea, bronchospasm, and right-sided cardiac valvular lesions.

Reye Syndrome

Rare, severe pediatric condition caused by treating viral infections (influenza B, VZV) with aspirin, characterized by mitochondrial failure, microvesicular steatosis of hepatocytes, severe hypoglycemia, and encephalopathy.

Wilson Disease

Autosomal recessive defect in hepatocyte copper-transporting ATPase (ATP7B gene), impairing copper incorporation into ceruloplasmin and biliary excretion, leading to toxic copper accumulation in the liver, brain, and cornea (Kayser-Fleischer rings).

Hemochromatosis

Recessive disorder caused by HFE gene mutations that impair hepcidin regulation, leading to excessive intestinal iron absorption, raised ferritin and transferrin saturation, and tissue injury (bronze diabetes, cirrhosis, dilated cardiomyopathy).

Gallstone Ileus

Mechanical intestinal obstruction occurring when a large gallstone erodes through a cholecystenteric fistula into the bowel lumen and becomes trapped at the narrowest region, the ileocecal valve.