Category Archives: Small Intestine

Small Intestine Carcinoid Tumors

Small Intestine Carcinoid Tumors

Clinical: associations MEN, ZES, sporadic
- associated carcinoid syndrome if liver metastases present

Treatment: surgical excision of tumor and regional lymph nodes, excise solitary liver metastases

5 year survival: 50-65% (85% if confined to bowel wall vs. 5% if serosal invasion)

Gross: submucosal, can ulcerate
- bright yellow after formalin fixation

Histology:

- architecture: insular (nests), acinar, trabecular
duodenum jejuno-ileal
<2cm    >2cm
indolent    aggressive
muc/submucosa    muc/submucosa
somatostatinomas (peri-ampullary with psammoma bodies)    serotonin-prod
gastrinoma    gastrinoma

Location: ileum > jejunum > duodenum

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Duodenum Peptic Ulcer

Duodenum Peptic Ulcer

Clinical presentation: H.pylori, ZES, smoking
Pathophysiology: gastric acid hypersecretion (balance between aggressive factors and defensive factors?see stomach)
Gross:
- punched out lesion (well defined margins)
- multiple lesions?think ZES

Histology

- abrupt lesions with normal adjacent mucosa
- gastric metaplasia
- chronic duodenitis
- Brunner’s gland hyperplasia
- Helicobacter pylori often present

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Tuberculosis Small Intestine Infection

Tuberculosis Small Intestine Infection

- associated with HIV

Location: ileocecal

Histology

- caseating or noncaseating granulomas, ulceration and desmoplasia

Positive stains: FAFB, ZN

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Mycobacterium Avium Intracellulare

Mycobacterium Avium Intracellulare

- associated HIV

Location

- small bowel unremarkable grossly

Histology

- macrophages and cytoplasmic rods in lamina propria
- minimal inflammation

Differential diagnosis

- Whipple’s disease but without fat vacuoles

Positive stains: FAFB, ZN

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Microsporidia

Microsporidia

Clinical presentation

- associated immunosuppression, HIV

Diagnosis: stool examination, PCR

Histology

- minimal or no changes in mucosa

Spores: 1.5 mm dots in enterocytes; may be surrounded by halos
Nucleated sporont: 3-5 micron, rounded, basophilic structure often surrounded by a halo

Positive stains: Giemsa

Electron microscopy

- helpful in diagnosis

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Cryptosporidiosis

Cryptosporidiosis

Cryptosporidium enteritis

Clinical presentation: severe, watery diarrhea resistant to most therapy
Diagnosis: acid-fast infective oocyst in stool

Histology

- 2-5 micron basophilic spherical structures attached to microvillus surface of epithelium
- variable villus changes, eosinophils
Positive stains: Giemsa, silver stains, PAS

Differential diagnosis

- mucin, cellular debris

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AIDS Related Inflammatory Diseases

AIDS Related Inflammatory Diseases

AIDS-related inflammatory diseases

- adenovirus, CMV, Cryptococcus, Histoplasmosis, Giardia, Histoplasma, MAI, Kaposi Sarcoma

Histology

- focal apoptosis deep in colonic crypts

Differential diagnosis

- graft vs. host disease, bowel preparation

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Giardia

Giardia

Giardia Lamblia

Clinical presentation

- malabsorption, chronic diarrhea

Diagnosis

- detect cysts, trophozoites or antigens in stool

Histology

- variable villous blunting, increased chronic inflammation
- Giardia: pear shaped with 2 nuclei, in lumen

Positive stains: Giemsa stain

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Whipple Disease

Whipple Disease

Etiology: Tropheryma whipplei
Gross appearance: shaggy, edematous

Histology

- mild blunted villi
- fat globules (actually distended lacteal)
- foamy histocytes

Special stains

- PAS-D + intracellular granules

Immunohistochemistry

- antibody anti-Whipple, PCR

Differential diagnosis

- MAI, malakoplakia, muciphages (macrophages containing mucin), mineral oil ingestion

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Tropical Sprue

Tropical Sprue

- post-infectious sprue
Symptoms: malabsorption within weeks of acute diarrheal enteric infection
Treatment: broad-spectrum antibiotics

Histology

- variable villous atrophy (none, partial, total); injury to entire small bowel (not proximal as in celiac sprue), inflammatory infiltrate, crypt hyperplasia

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