Digestive System III Pathology – Malabsorption, Dysentery & Inflammatory Bowel Disease

A comprehensive set of question-and-answer flashcards covering diarrhea types, malabsorption syndromes, celiac disease, tropical sprue, dysenteries, and inflammatory bowel disease, including Crohn’s disease and ulcerative colitis.

What daily stool weight defines a diarrheal disease?

200 g of stool per day

Which type of diarrhea produces isotonic stool that persists during fasting?

Secretory diarrhea

Which diarrhea results from unabsorbed luminal solutes and stops with fasting?

Osmotic diarrhea

Which diarrhea is associated with steatorrhea and is relieved by fasting?

Malabsorptive diarrhea

Which diarrhea presents with purulent, bloody stools that continue during fasting?

Exudative diarrhea

What is the hallmark clinical finding of malabsorption?

Steatorrhea—bulky, frothy, greasy, yellow or clay-colored stools rich in fat

List three systemic manifestations of chronic malabsorption.

Weight loss, abdominal distention/borborygmi, and muscle wasting (also anorexia)

Name four important causes of malabsorption mentioned in the lecture.

Celiac disease, tropical sprue, chronic pancreatitis, cystic fibrosis (many others acceptable)

By what other names is celiac disease known?

Celiac sprue or gluten-sensitive enteropathy

What dietary component triggers celiac disease?

Gluten (specifically gliadin peptides) in genetically susceptible individuals

Which HLA haplotypes are most strongly linked to celiac disease?

HLA-DQ2 or HLA-DQ8

Which three autoantibodies are characteristic of celiac disease?

Anti-tissue transglutaminase (tTG), anti-endomysial, and anti-gliadin antibodies

What are the classic small-bowel histologic changes in celiac disease?

Villous atrophy, crypt hyperplasia, and increased intraepithelial lymphocytes

Into what three clinical categories can celiac disease presentations be grouped?

Classical, non-classical, and subclinical

Give two classical intestinal manifestations of celiac disease.

Chronic diarrhea and weight loss (also abdominal pain, bloating, poor appetite, distension)

Give two non-classical extra-intestinal manifestations of celiac disease.

Iron-deficiency anemia, dermatitis herpetiformis, chronic fatigue, short stature, alopecia, etc.

Which serologic test is the most sensitive for active celiac disease?

IgA anti-tissue transglutaminase (anti-TG2) antibody

Which serologic test is nearly 100 % specific for celiac disease?

IgA anti-endomysial antibody (EMA)

From which part of the intestine are biopsies typically taken to diagnose celiac disease?

Second portion of the duodenum or proximal jejunum

When can biopsy be omitted in pediatric celiac diagnosis under European guidelines?

If IgA anti-TG2 exceeds 10× the upper normal limit and IgA-EMA is positive on a second sample

What differentiates tropical sprue from celiac disease regarding gluten intake?

Tropical sprue does NOT improve on gluten withdrawal

What organisms are implicated in tropical sprue pathogenesis?

Enteric bacteria such as Escherichia coli, Klebsiella, and Enterobacter species

What is the standard treatment for tropical sprue?

Tetracycline with folate supplementation for ~6 months

Which bacterium is the most common cause of bacillary dysentery?

Shigella sonnei

Which Shigella species can produce necrosis resembling ulcerative colitis?

Shigella flexneri and Shigella dysenteriae

Histologically, what infiltrate characterizes acute bacillary dysentery?

Neutrophilic infiltrate with cryptitis and crypt abscesses

What protozoan causes amoebic dysentery?

Entamoeba histolytica

Which two colonic regions are most often affected by amoebic dysentery?

Cecum and ascending colon

What is the classic gross ulcer shape produced by E. histolytica invasion?

Flask-shaped ulcers

Name two serious colonic complications of amoebic dysentery.

Fulminant/necrotizing colitis and toxic megacolon (others: ameboma, perforation, strictures)

What serious extra-intestinal complication results from amoebic liver abscess rupture?

Intraperitoneal, intrathoracic, or intrapericardial rupture possibly leading to secondary infection

Define ameboma.

An inflammatory (pseudotumor) mass of granulation tissue and fibrosis mimicking carcinoma, usually in cecum/ascending colon

What fundamental mechanism underlies inflammatory bowel disease (IBD)?

Inappropriate mucosal immune activation toward intestinal microbiota in genetically predisposed hosts

How does Crohn’s disease typically involve the GI tract?

Discontinuous, segmental, transmural lesions affecting any part from mouth to anus

List two hallmark histologic features of Crohn’s disease.

Transmural inflammation with lymphoid aggregates and non-caseating granulomas (≈50 % of cases)

Name three classic gross findings in Crohn’s disease.

Creeping fat, cobblestone mucosa with aphthous ulcers, and bowel wall thickening/strictures (also fistulas)

What microscopic pattern distinguishes Crohn’s disease distribution?

Patchy, segmental ‘skip’ lesions with intervening normal mucosa

Where does ulcerative colitis always begin, and how does it spread?

Begins in the rectum and extends proximally in a continuous pattern

In ulcerative colitis, inflammation is limited to which layers?

Mucosa and submucosa (no transmural inflammation)

Which histologic features of chronicity are seen in ulcerative colitis?

Crypt architectural distortion, basal lymphoplasmacytosis, and Paneth cell metaplasia

What gross lesions are common in ulcerative colitis but absent in Crohn’s disease?

Continuous superficial ulceration and pseudopolyps without skip lesions or creeping fat

How does the risk of colorectal carcinoma change in ulcerative colitis?

Risk increases with duration of disease and severity/extent of inflammation

State one key pathologic difference between Crohn’s disease and ulcerative colitis.

Granulomas and transmural inflammation are common in Crohn’s but absent in ulcerative colitis