Infectious colitis (specific microorganisms)
Self limited disease in immunocompetent, severe explosive watery diarrhea in AIDS/immunocompromised patients
Colonic involvement less frequent than small bowel
Often overlooked in AIDS patients (Archives 2001;125:1042)
Treatment: no reliable antibiotics in immunosuppressed; in transplant patients, use antibiotics and reduction in immunosuppression (Clin Nephrol 2005;63:305)
Diagnosis: acid-fast oocyst in stool specimens
Micro: intracellular but extracytoplasmic basophilic dots three microns in diameter on luminal border of epithelial cells; also cryptitis and epithelial apoptosis (AIDS 1998;12:2459)
Micro images: various images #1; #2; small blue organisms at luminal border #1; #2; #3; oocyst in fecal smear
Positive stains: Giemsa for biopsies, acid-fast oocyst in stool
EM images: located just below plasma membrane of host
References: Centers for Disease Control, eMedicine
Causes various forms of colitis
Enteroaggregative E. coli
Pattern of adherence is characterized by self-agglutination, which is called aggregative adherence
Common cause of diarrhea (Clin Infect Dis 2006;43:402)
Affects infants and adults, those in developing countries, HIV+ patients, but also those without foreign travel or immunodeficiency
Fever, abdominal pain and diarrhea >14 days
EM images: various images
References: Centers for Disease Control
Enterohemorrhagic E. coli
Major foodborne pathogen (ground beef and salami, unpasteurized milk and juice, sprouts, lettuce), contact with cattle, swimming in contaminated waters
Diarrhea and vomiting; also hemorrhagic colitis (abdominal cramping, bloody diarrhea, no/low grade fever) and hemolytic uremic syndrome
Due to Shiga-like toxin in O157:H7 strains
Reportable to state health departments in US
Outbreaks: unpasteurized gouda cheese in Alberta, Canada in 2002 (Can J Public Health 2005;96:182), uncooked hamburger meat in Washington State in 1992-3 (JAMA 1994;272:1349, West J Med 1996;165:15), swallowing contaminated lake water in Oregon in 1991 (N Engl J Med 1994;331:579)
Diagnosis: PCR (Mol Cell Probes 2006;20:31), enzyme immunoassay (J Clin Microbiol 2004;42:1652)
Micro: hemorrhage and edema in lamina propria; focal necrosis of superficial epithelium, acute inflammation; may have inflammatory pseudomembranes
Micro images: various images
DD: ischemic colitis
References: Wikipedia
Enteroinvasive E. coli
Causes dysentery
Similar molecular features as Shigella (Infect Immun 2004;72:5080), due to virulence plasmid that encodes determinants for entry into epithelial cells and dissemination from cell to cell
Due to contaminated cheese, water or person to person spread
Micro: bacterial invasion and destruction of colonic mucosa
Enteropathogenic E. coli
Major cause of infant diarrhea in developing countries
Due to contaminated water or feed
Has pathogenicity island that encodes proteins which modulate the actin microtubule and intermediate filament networks to allow intimate attachment of bacteria to plasma membrane of infected enterocytes, forming attachment and effacing lesions (J Bacteriol 2006;188:3110); also have large plasmid containing cluster of genes encoding bundle-forming pili
“Atypical” cases: lack bundle-forming pili, associated with prolonged diarrhea (Emerg Infect Dis 2006;12:597)
Micro: effacement of brush border microvilli of enterocytes, no bacterial invasion, but surface adherent organisms may be identifiable
EM images: various images; E. coli pili
Enterotoxigenic E. coli
Causes traveler’s diarrhea in 20-50% who travel from industrialized world to developing countries, and infant diarrhea in less developed countries
Due to contaminated food and water
Also an emerging causing of diarrhea in US
Due to enterotoxin (heat-labile or heat-stable) produced by non-invasive bacteria that adhere to small intestine and produce cholera-like watery diarrhea
Prevention: chemoprophylaxis with rifaximin, careful food/beverage selection (Drugs 2006;66:303)
Micro: usually no histologic changes
References: Clin Microbiol Rev 2006;19:583, Clin Microbiol Rev 2005;18:465, Centers for Disease Control, World Health Organization
Case reports: Korean woman with migrating fluke into cecum and associated inflammatory reaction (AJSP 1984;8:73)
Micro images: egg in fecal smear
Case reports: 44 year old African American woman with history of AIDS and Hepatitis C and a colonic mass (Archives 2005;129:259), nonimmunocompromised patient with colonic mass (Am Surg 2004;70:959), cecal perforation (J Clin Pathol 1988;41:992)
Gross images: polypoid lesion of cecum
Micro: yeast within macrophages
Micro images: submucosal macrophages filled with yeast forms; figure 1-colonoscopy, 2/3-H&E, 4-GMS; liver
Positive stains: GMS
Associated with adenovirus, CMV, Cryptosporidium, Giardia, Histoplasma, Mycobacterium avium intracellulare, Pneumocystis, spirochetosis, Kaposi’s sarcoma
Some cases have no diagnosis even after expert review and may be due to HIV virus itself
Adenovirus and infectious causes are often overlooked on biopsies of patients with negative stool studies or no response to therapy (Archives 2001;125:1042)
Bacterial infections are best identified by stool culture
Primary AIDS related enterocolitis - causes severe diarrhea with no identifiable cause; apoptosis deep in colonic crypts resembling grade 1 graft vs. host disease
Micro: diffuse and nodular lymphoid hyperplasia with germinal centers; multinucleated giant cells and mononuclear cells within lamina propria (Mod Path 1999;12:75)
HSV (herpes simplex virus) colitis
Painful discrete ulcers, vesicles or pustular lesions in distal rectum or perianal skin
Diagnose with viral culture
Case reports: patient with common variable immunodeficiency syndrome (Eur J Gastroenterol Hepatol 2006;18:541), neonate (Pediatr Infect Dis J 2002;21:887), post-transplant (Pediatr Transplant 2001;5:374)
Micro: ulceration with neutrophils in lamina propria, cryptitis, crypt abscess, multinucleated giant cells, inclusions in anal transition zone epithelium and perianal skin
Micro images: esophagus
Acute self-limited colitis may be due to infections, drugs or gluteraldehyde disinfection of endoscope (Endoscopy 1998;30:428)
May not always be self-limited
Due to (a) ingestion of pre-formed toxins (Staphylococcus aureus, Vibrio cholera, Clostridium perfringens, causes symptoms within hours including explosive diarrhea), (b) infection by toxigenic organisms (incubation of hours or days) or (c) infection by enteroinvasive organisms which invade and destroy mucosal epithelium cells
Bacterial virulence factors include (a) adherence to epithelial cells, (b) enterotoxins, (c) invasion factors, (d) cytotoxicity
(a) Adherence: via fimbriae or pili; the process of adherence destroys the microvilli brush border
(b) Enterotoxins: toxin binds to cell membrane, enters cell, activates massive electrolyte secretion (cholera toxin, E. coli heat-labile and heat-stable toxins produce travelers diarrhea); no white blood cells in stool
(c) Invasion factors: enteroinvasive E. coli and Shigella invade via microbe-simulated endocytosis; then intracellular proliferation, cell lysis, cell to cell spread
(d) Cytotoxicity: Shiga toxin, enterohemorrhagic E. coli
Complications: due to massive fluid loss and loss of mucosal barrier; include dehydration, sepsis, perforation
Micro: inflammation of lamina propria (active much greater than chronic), edema, hemorrhage; severe cases have crypt abscesses, extensive necrosis, hemorrhage and thrombi
Micro images: infectious colitis #1; #2; #3; #4; #5; #6; #7; #8; #9; mild superficial increase in chronic inflammation;
DD: ulcerative colitis (crypt distortion, plasma cells at base of crypts, AJSP 1982;6:523)
Associated with HIV infection; recommended to perform acid-fast stain on all mucosal biopsies in HIV+ patients
If present in gut, is usually disseminated, with positive stool and blood cultures
May be due to contaminated endoscope (Kekkaku 1995;70:629)
Case reports: causing severe GI bleeding in immunosuppressed patient (Am J Gastroenterol 1999;94:232), M. xenopi causing colonic stricture (Postgrad Med J 2003;79:705)
Micro: macrophages with cytoplasmic rods filling lamina propria; resembles Whipple’s disease but without fat vacuoles
Micro images: histiocytes with finely granular cytoplasm #1; #2; #3; #4; PAS; Ziehl-Neelsen acid-fast stain; acid-fast stain #1; #2; #3; #4; figure F
Positive stains: acid-fast, PAS (faintly positive bacillary forms)
Most common cause of gastroenteritis in infants and young children worldwide
Usually self-limited disease in US, although major cause of childhood death (up to 500K annual deaths) in developing countries
Varies from mild watery diarrhea to severe diarrhea leading to dehydration and shock
Vaccine licensed for US infants in 2006 (MMWR Recomm Rep 2006;55:1)
Case reports: fatal cases in young children due to diffuse endotheliatis and associated tissue damage (Hum Path 2001;32:216), outbreak in a transplant unit (Transpl Int 2005;18:470)
Diagnosis: enzyme immunoassay
Micro images: B cells in lamina propria
Usually affects terminal ileum, occasionally colon
Invades via transcytosis with minimal epithelial damage
Due to contaminated milk, eggs, beef, poultry
Causes dysentery, bacteremia (see typhoid fever)
Case reports: causing toxic megacolon (Int J Colorectal Dis 2002;17:275, Acta Paediatr Taiwan 2000;41:43), causing obstruction (Pediatr Surg Int 2000;16:525), Salmonella dublin causing spontaneous bacterial peritonitis in cirrhosis patient (Eur J Gastroenterol Hepatol 2001;13:587)
Micro: mild cases show colonic mucosal edema with acute inflammation but preservation of crypt architecture; occasional crypt abscesses; severe cases show neutrophils invading degenerating crypts with possible microthrombi and mucus depletion
DD: ulcerative colitis (Histopathology 1978;2:117)
References: AJSP 1979;3:483, eMedicine #1, #2, Centers for Disease Control
Fluke that causes colitis or bowel obstruction
Associated with underdeveloped countries, and living near dam reservoirs (Lancet Infect Dis 2006;6:411)
S. haematobium: Africa and Middle East; usually affects bladder; diagnosed with urine examination
S. intercalatum: central West Africa; uncommon
S.
japonicum: Southeast Asia and
western Pacific countries; diagnose with stool examination
S. mansoni: South America, Caribbean, Africa and Middle East; diagnose
with stool examination
S. mekongi: Southeast Asia; uncommon
Case reports: 78 year old man with rectal adenocarcinoma, with endometriosis (Fertil Steril 2006;85:1060.e1)
Gross images: Schistosoma granulomas
Micro: focal ulcers, eggs may be calcified, surrounded by fibrosis or surrounded by granuloma
Micro:
S.
haematobium - eggs are 110-170 x
40-70 microns, oval with terminal spine
S. japonicum
- eggs are 70-100 x 55-65 microns,
oval/round (more rounded than other types), minute subterminal or no spine
S. mansoni - eggs are 110-175 by 45-70 microns with thin transparent shell and definite lateral spine
Micro images: S. mansoni and S. japonicum
S. haematobium - fluke; eggs #1; #2; #3; #4
S. japonicum - fluke; eggs #1; #2; #3
S. mansoni - fluke #1; #2; eggs #1; #2; #3
within tissue, type not identifiable - #1; #2; #3; granuloma surrounding egg
Micro images contributed by Dr. Lisa Cerilli: within colonic mucosa #1; #2; #3; #4; #5; #6
Virtual slides: schistosomiasis
References: eMedicine #1, #2, Centers for Disease Control, Wikipedia, World Health Organization, Archives 2005;129:544 (S. mansoni)
Invades distal colon
Low inoculum needed to cause disease
Person to person spread; can occur in epidemics
Produces purulent exudates, dysentery
Gross: colonic mucosal damage and ulceration
Gross images: Shigella colitis
Micro: marked acute and chronic inflammatory mucosal infiltrate, with ulceration, epithelial cell necrosis, mucus depletion and hemorrhage; occasional crypt abscesses
Virtual slides: dysentery (organism not identified)
References: Centers for Disease Control, eMedicine #1, #2
Colonization of colon by relatively non-pathogenic spirochetes
Seen in 3-10% of normal patients; associated with anal intercourse (present in 30% of male homosexuals), HIV, lower socioeconomic conditions
May cause persistent diarrhea, possibly due to blunting and destruction of microvilli (AJCP 1986;86:679)
Best characterized species are Brachyspira aalborgi and Serpulina pilosicoli
Case reports: 2 year old with failure to thrive (Johns Hopkins),
25 year old HIV+ man with CMV colitis (University of Pittsburgh),
48 year old man with prolonged diarrhea (Case of Week #213),
50 year old man with coexisting amebiasis (Case of Week #257)
Treatment: metronidazole if symptomatic
Micro: spirochetes accentuate luminal border (by embedding into enterocytes in parallel alignment), produces blue haematoxyphilic line between the microvilli of the covering epithelium (Pathologe 2003;24:192); minimal inflammation
Micro images: accentuation of luminal border #1; #2; #3; #4; various images #1; #2; Warthin-Starry #1; #2; #3
Positive stains: silver stains (Warthin-Starry, Dieterle, Churukian-Schenk), PAS, Giemsa, Alcian-blue (pH 2.5)
EM images: long coiled bacteria are adherent to microvilli
References: Archives 2001;125:699, AJCP 2003;120:828
Typically associated with immunodeficiency and small intestinal or pulmonary manifestations
Few larvae present in colon, may delay diagnosis due to difficulty in identification (Ann Diagn Pathol 2003;7:87)
Case reports: nonimmunocompromised man with diarrhea, weight loss and microcytic anemia (J Clin Gastroenterol 1999;28:77), mimicking ulcerative colitis (J R Coll Surg Edinb 1997;42:202), causing chronic colitis (Am J Trop Med Hyg 1983;32:1289), pseudopolyposis (Surg Endosc 1987;1:175), presenting with massive bleeding (Arch Intern Med 1980;140:1061), bowel infarction (Trans R Soc Trop Med Hyg 1975;69:473)
Gross images: adult female worm
Micro: rarely see eosinophilic granulomatous inflammation of colon wall clinically resembling inflammatory bowel disease (AJSP 1996;20:693)
Micro images: larvae in stool
Case report: primary syphilis in rectum (J Korean Med Sci 2005;20:886)
Micro: obliterative endarteritis with plasma cells; variable granulomas
Due to Trichuris trichiura (whipworm)
Symptoms vary from none to bloody diarrhea
May cause rectal prolapse in children
May mimic acute appendicitis
Case reports: bloody diarrhea due to massive infestation (J Trop Pediatr 2006;52:66), resembling a sessile polyp (Ital J Gastroenterol Hepatol 1997;29:365)
Gross images: infestation with mucosal hemorrhage
Micro: focal ulcers; adult worms present
Micro images: worm #1; #2 (figure 2)
EM images: worm
References: eMedicine, Centers for Disease Control
May involve GI tract even with minimal or inactive pulmonary disease (Hong Kong Med J 2006;12:264), usually small intestine and ileocecal area (Gastroenterol Clin Biol 2005;29:419)
Diagnosis may be difficult and require exploratory laparoscopy (Scand J Gastroenterol 2005;40:240)
Pain, diarrhea, weight loss, fever
50% have palpable mass; may cause obstruction and stricture (Endoscopy 2004;36:1099); peritonitis rare
Case reports: colonic perforation (Dis Colon Rectum 2004;47:2211), massive melena (Int J Clin Pract 2004;58:1162), high adenosine deaminase in ascites fluid (Kansenshogaku Zasshi 2004;78:916), coexisting carcinoma (Trop Gastroenterol 2003;24:137), treated initially as Crohn’s disease (World J Gastroenterol 2003;9:2382)
Treatment: surgery for cecal masses or perforation, antibiotics
Gross: ulceration, diffuse fibrosis through colonic wall
Gross images: tuberculosis #1; #2
Micro: caseating or noncaseating granulomas, ulceration and desmoplasia; variable vasculitis, mural fibrosis, granulomas in mesenteric lymph nodes
Micro images: various images; mucosal granulomas #1; #2 (figure 1)
Positive stains: acid fast bacilli
DD: Crohn’s disease (much more common in US and western Europe, no acid fast bacilli, no caseation, no coalescing granulomas)
References: eMedicine
Due to Salmonella typhi, which enters epithelial cells via cystic fibrosis transmembrane conductance regulator (CFTR mutations cause cystic fibrosis, Nature 1998;393:79)
Causes bacteremia, fever, chronic infection of joints, biliary tree, bones and meninges
Causes intestinal bleeding due to ulcers in distal ileum or proximal colon (Dig Liver Dis 2004;36:141); bleeding may be massive (Dis Colon Rectum 1986;29:511)
Case reports: colonic perforation (J Coll Physicians Surg Pak 2004;14:634), toxic megacolon (Acta Paediatr Taiwan 2000;41:43), skip ulcers (J Gastroenterol 1999;34:700), splenic abscess and colonic fistula (Gastroenterol Clin Biol 1998;22:1102)
Gross images: perforation at site of Peyer’s patches
Micro: hyperplasia, mucosal necrosis and sloughing, ulceration; macrophages contain bacteria, red blood cells and lymphocytes; macrophage aggregates are called typhoid nodules, present in intestine and nodes (also other sites);
Micro images: typhoid nodules (microgranulomas) in ileal wall
References: eMedicine #1, #2
Produces enterotoxin that causes profuse watery diarrhea; bacteria is not invasive
From contaminated water or shellfish, causes pandemics by person-to-person contact
Treatment: oral rehydration and adequate sanitation; antibiotics or vaccines do not have a major role
References: Centers for Disease Control, Wikipedia, World Health Organization, University of Wisconsin, eMedicine
Yersinia enterocolitica
Causes diarrhea (mild self limited to typhoid fever-like disease), may cause peritonitis, pharyngitis, pericarditis
From contaminated milk or pork
Invades ileal mucosa, multiplies in Peyer’s patches and regional lymph nodes; also affects right colon and appendix
May cause arthritis (Clin Infect Dis 1997;25:831); may trigger collagenous colitis in some cases (Dig Dis Sci 1998;43:1341, Scand J Gastroenterol 2002;37:711)
Case reports: infection in patient with hemachromatosis simulating colon cancer with liver metastases (Dis Colon Rectum 2005;48:390), simulating Crohn’s disease (Pediatrics 1999;104:e36), causing colonic abscess (Dis Colon Rectum 1990;33:985)
Micro: ulcers overlying lymphoid nodules, necrotizing microgranulomas
Micro images: various images
Gram stain: gram negative rods; aerobic and motile
References: eMedicine #1, #2, infections in Norway
Yersinia pseudotuberculosis
Micro: similar to Y. enterocolitis plus true granulomas with neutrophilic core
References: eMedicine, outbreak in British Columbia, Canada
Non-neoplastic, non-congenital lesions
Cause hospital admissions in up to 1/3 within 10 years of colorectal surgery (Dis Colon Rectum 2001;44:822)
Also due to infections and endometriosis
Commonly occur between bowel segments or abdominal wall and operative site
May create internal herniations (closed loops through which viscera slide)
Rarely are congenital
Rarely cause colonic obstruction (Am Surg 1984;50:479)
Gross images: between loops of small intestine
Diagnose with rectal biopsy that includes submucosa
Amyloid tumor may clinically resemble carcinoma (AJR Am J Roentgenol 2002;179:536)
Associated with hemodialysis (Gastroenterology 1989;96:230, Clin Nephrol 2000;53:394, Mod Pathol 1995;8:577)
Rarely AL amyloid is localized to colon, and does not require systemic treatment (Amyloid 2003;10:36)
Case reports: amyloid tumor with synchronous adenocarcinoma (J Clin Pathol 1995;48:592)
Gross images: amyloid tumor (above) and adenocarcinoma arising from villous adenoma (below)
Micro: amyloid present in blood vessel walls and muscularis propria; may be subepithelial; may cause ischemic changes in colon
Micro images: rectal biopsy; submucosal vessel involvement #1; #2; #3 with Congo Red stain; #5 with Congo Red stain highlights vessel wall and free submucosal amyloid; #6 with Congo Red stain and polarized light; subepithelial deposits resemble collagenous colitis #1; #2 (Congo Red stain)
DD: collagenous colitis (surface epithelial damage, epithelial lymphocytes)
Angiolymphoid hyperplasia with eosinophilia in colon
Also called epithelioid hemangioma
Usually skin; rare in colon with only one case report
Case reports: 63 year old man with severe GI hemorrhage requiring hemicolectomy (J Clin Pathol 1997;50:611)
Micro: sheet of lymphocytes and eosinophils associated with vessels containing plump and pleomorphic endothelial cells
Micro images: lobular inflammatory infiltrate; dense infiltrate with adjacent distorted vessel; vessels lined by hobnail epithelial cells; artery at base of lesion shows severe distortion and reduplication of internal elastic lamina
Rare; may occur after barium enema if barium penetrates mucosal tear and stimulates a granulomatous reaction
Crystals are visible under polarized light
Usually an incidental finding; rarely produces polypoid or ulcerated lesion resembling a neoplasm
Case reports: rectum (Ann Surg 1975;181:418)
Micro: barium is green, crystalline and refractile; crystals occur in clusters in macrophages or connective tissue
Micro images: low power
References: Histol Histopathol 1992;7:625
Autopsy finding associated with enteral feeding containing food coloring (Archives 2000;124:1397, Archives 2001;125:599)
Food coloring is used to identify either aspirated gastric contents in suctioned airway fluids or the source of fistulous drainage
Gross images: blue colon; green colon
Also called ceroidosis
Rare; affects small or large intestine with lipofuscin deposits in smooth muscle cells of muscularis propria, occasionally muscularis mucosa and vessel walls (Cesk Patol 1994;30:23)
Vitamin E deficiency, secondary to malnutrition (Am J Gastroenterol 1996;91:1450, J Formos Med Assoc 1993;92:1090), or celiac sprue (Rev Esp Enferm Dig 1993;83:281, Med Wieku Rozwoj 2003;7:593) causes mitochondrial myopathy affecting smooth muscle of GI tract, leading to atonic and dilated bowel and pseudoobstruction (Archives 1990;114:76); lipofuscin deposits reflect mitochondrial injury
Case reports: anorectal functional deficit (Ir J Med Sci 1994;163:404), associated with GI adenocarcinoma (J Clin Gastroenterol 1993;16:48)
Treatment: vitamin E, resection of affected bowel
Gross: dark brown or orange-brown discoloration of bowel wall, which is often dilated
Micro: lipofuscin deposits in muscularis propria and muscularis mucosa
Micro images of lipofuscin (ceroid) pigment: smooth muscle of vas deferens; smooth muscle of jejunum; submucosal blood vessel; PAS highlights lipofuscin in esophageal wall
Positive stains: PAS, golden-yellow autofluorescence under ultraviolet light
EM: degradation of smooth muscle mitochondria (Scand J Gastroenterol 1990;25:66)
DD: melanosis coli, blue/green colon
References: Am Surg 1989;55:566, J Clin Pathol 1987;40:798
Colchicine is used to treat gout, constipation (Am J Gastroenterol 2003;98:1112) and other disorders
Case reports: accidental ingestion of meadow saffron / autumn crocus / naked lady, which contains colchicine (J Forensic Sci 2002;47:1391), colchicine effect in hyperplastic polyp (Archives 2002;126:615)
Images: meadow saffron plant and colchicine structure
Micro: abundant epithelial mitotic figures with metaphase arrest; often enlarged epithelial cells with condensed chromatin in a ring formation within center of cell; associated with epithelial loss of polarity and pseudostratification; nuclei small, hyperchromatic and compressed to periphery of cell
Micro images: colchicine effect in hyperplastic polyp
References: AJSP 2001;25:1067
Uncommon
Cysts containing mucus in colonic submucosa; either localized or diffuse
Similar histology to colorectal polyps in Cowden’s syndrome
Localized: called hamartomatous inverted polyp, localized 5-12 cm from anal margin, presents as nodule or plaque, associated with chronic proctitis
Diffuse: secondary to ulcerative colitis, Crohn’s disease, radiation or other inflammation / ulceration of bowel; mucus follows granulation tracts to involve large areas of bowel
Case reports: after radiation for bladder carcinoma (Archives 1995;119:1170), recurrence after 20 years (Chir Ital 2005;57:789)
Treatment: patient education to avoid straining, high fiber diet with bulk laxatives, surgery for rectal prolapse
DD: mucinous adenocarcinoma or colloid carcinoma (infiltrating, epithelium floats in mucin, glandular atypia, tumor desmoplasia, no hemorrhage or hemosiderin, no lamina propria), ulcerative colitis (no fibromuscular obliteration of lamina propria)
Endometriosis of colon
Rarely associated with neoplasms or precancerous changes (AJSP 2000;24:513)
Case reports: with schistosomiasis (Fertil Steril 2006;85:1060.e1), causing obstruction of sigmoid colon (Ugeskr Laeger 2005;167:3604), with endometrioid adenocarcinoma (Am Surg 2005;71:694), with endometrial stroma sarcoma (J Korean Med Sci 2002;17:412), with clear cell carcinoma (J Clin Pathol 2001;54:76), with mixed germ cell tumor (AJCP 1982;78:555)
Gross: serosa and subserosa nodules < 5 cm; smooth muscle hypertrophy may cause obstruction; gray cut surface with minute areas of hemorrhage
Gross images: image1
Micro: endometrial glands, stroma, hemosiderin in deeper layers; usually surrounded by smooth muscle; epithelium may have inflammation and ulcers simulating inflammatory bowel disease or solitary rectal ulcer syndrome; often infiltrates along nerves of bowel wall (Hum Reprod 2004;19:996), mucosa usually normal; bowel wall may be fibrotic
Micro images: endometriosis #1; #2; #3; infiltration along nerves #1; #2; in pericolic lymph nodes (figures 3/4)
Negative stains: CEA
DD: adenocarcinoma (BMC Gastroenterol 2003;3:18)
Fusiform strictures of colon associated with childhood cystic fibrosis
May be due to ingestion of high strength pancreatic supplements
Affects right colon or entire colon
Case reports: in adult long after discontinuance of pancreatic enzymes (South Med J 2004;97:901), in newborn with cystic fibrosis before receiving enzymes (J Pediatr Gastroenterol Nutr 2002;35:356)
Gross: cobblestone appearance
Micro: severe submucosal fibrosis with thickening of muscularis propria and chronic mucosal inflammation, including eosinophils and mast cells; variable active cryptitis
Micro images: mucosal inflammation and submucosal fibrosis
References: Hum Path 1997;28:395
Associated with lipomas causing intussusception (Pathol Int 2005;55:160, J Clin Pathol 1993;46:91) or obstruction (Am Surg 2001;67:491); also HIV, arteriovenous malformation
Benign, appears reactive
Gross: colonic mass
Gross images: irregular mucosa (large arrow) next to lipoma (small arrow)
Micro: florid lobular proliferation of small vascular channels lined by plump endothelial cells in submucosa or muscular wall; minimal/no atypia, no/rare mitotic figures present; mucosal ulceration and muscular fibroplasia in adjacent lamina propria suggest mucosal prolapse; often ischemic type changes
Micro images: adjacent to chronic ulcer; increased cellularity and spindled cells; ischemic type changes; possible adjacent AV malformation; vascular proliferation without inflammation or ulceration
DD: angiosarcoma
References: Mod Path 2001;14:1114
Often in rectum, <50 cases reported
Associated with other heterotopia, vertebral and digital anomalies
Mean age 18 years but wide range
In rectum, usually presents with rectal bleeding and tenesmus (J Clin Gastroenterol 1994;19:41)
Case reports: rectum (Archives 1999;123:222), associated with tubulovillous adenoma (N J Med 1995;92:512)
Treatment: excision, H2 blockers
Micro images: gastric and colonic mucosa #1; #2; gastric glands similar to those in fundus
Very rare
Case report: 37 year old black woman with SLE, diabetes, hypertension and tophus in colon (Hum Path 2004;35:897)
See Anus and perianal area Chapter
Rare; intraabdominal Pacinian corpuscles may enlarge up to 1 cm
Micro: resembles cutaneous counterpart with central blood vessel and nerve ending surrounded by 14-45 tortuous, concentric lamellae
DD: nematode (has cuticle, internal structures)
Severe and persistent constipation without a known cause
Cathartic colon is historic term for anatomic changes due to chronic laxative use
Usually women
Affects 5-30% in UK (Nurs Times 2005;101:59)
Treatment: may require colectomy
Gross: loss of haustral folds (J Clin Gastroenterol 1998;26:283)
Micro: melanosis coli due to laxative use; may have loss of neurons in myenteric plexus with silver stains; may have reduced CD117+ interstitial cells of Cajal
Cathartic colon: mucosa resembles snake skin, atrophic muscularis propria with decreased neurons in Auerbach plexus
References: National Institutes of Health
Case reports: due to giant cell arteritis (Medicina (B Aires) 1999;59:86), abdominal aortic aneurysm (Minerva Chir 1996;51:597)
Gross images: hemorrhagic infarct
Micro images: infarct #1; #2; #3
Due to twisting of normally think pedicles of fat on lateral colon
May be associated with obstruction and abscess (J Am Assoc Gynecol Laparosc 1996;3:325)
Gross: firm, gray-white nodules resembling metastatic tumor
Micro: central infarcted adipose tissue with peripheral fat necrosis and calcification, outer fibrotic and inflamed tissue
Common endoscopic finding
Grossly visible brown-black areas of colon after ingestion of anthracene-type laxatives
Typically involves all parts of colon and rectum, but spares mucosal regions with lymphoid nodules, polyps or carcinomas; thus, should biopsy nonpigmented regions in these patients
No associated with adenomas, although small polyps are more easily identified (Z Gastroenterol 1997;35:313)
Case reports: patient with Rett syndrome (autonomic neuropathy, constipation, severe CNS disease, Archives 2001;125:1110), in pericolonic nodes of patient taking laxative (Archives 2004;128:565)
Gross images: darkly pigmented colonic mucosa #1; #2 (terminal ileum is normal color)
Micro: macrophages containing lipofuscin (melanin-like pigment) in lamina propria; silver stains may show abnormalities of myenteric plexus
Micro image: macrophages with brown pigment #1; #2; #3; #4; #5; PAS stain
Submucosal gas-filled cysts in GI tract; called mucosal pseudolipomatosis if it resembles lipomatosis (AJCP 1985;84:575)
Either benign or fulminant form
In infants, fulminant form is associated with necrotizing enterocolitis and may be fatal; also associated with cystic fibrosis or congenital heart defects
In adults, either idiopathic or associated with obstruction, chronic lung disease, scleroderma (Am J Med Sci 2006;332:100), chemotherapy, drugs, ischemic colitis
Often indolent clinical course, although radiographically resembles carcinoma
Considered a finding, not a diagnosis
Treatment: surgery if bowel necrosis, perforation or peritonitis
Endoscopy images: image1
Gross: polypoid grapelike masses protrude through mucosa
Gross images: pneumatosis intestinalis #1; #2; #3
Micro: submucosal cysts lined by multinucleated giant cells; mucosa contains cryptitis, crypt abscesses, granulomas; may also resemble lipomatosis
Micro images: pneumatosis intestinalis; due to infection and cystic fibrosis
DD: Crohn’s disease
References: Archives 1999;123:354, eMedicine
Reactive angioendotheliomatosis of colon
Case report: 19 year old Japanese male with Crohn’s disease and no cutaneous intravascular proliferations (AJSP 2004;28:257)
Micro: intravascular proliferation of endothelial cells resembling glomeruloid hemangioma
Also called mucosal prolapse syndrome (may be a better term since not necessarily solitary, ulcerated or rectal)
Rare; incidence of 1 per 100K per year
Similar to inflammatory cloacogenic polyp (lower rectum and anal transition zone)
Solitary or multiple ulcerated or polypoid lesions 4-18 cm from anal margin; may occur in anal canal or sigmoid
Usually age 20’s to 30’s, rarely in children (Pediatrics 2002;110:e79)
Often abnormal function of anal and pelvic floor musculature during defecation, causing rectal mucosal prolapse or intussusception
Associated with histologic changes of sessile serrated polyps (38%), which often have focal loss of hMLH1 gene expression (Archives 2005;129:1037)
Symptoms: constipation, blood and mucus from rectum, change in bowel habits, pain
Case reports: 41 year old man with rectal nodule
Treatment: reassurance, high fiber diet, laxatives, topic steroids
Gross: well demarcated irregular ulcer(s) on rectal wall; also polypoid, rough, erythematous lesions; mucosal thickening
Micro: superficial mucosal ulceration and villiform change, crypt hyperplasia and elongation with focal dilation (some diamond shaped), proliferation of fibroblasts and smooth muscle cells in edematous lamina propria, thickened muscularis mucosa with splayed fibers, ectatic capillaries, minimal inflammation; may have inflammatory pseudomembranes; late changes resemble colitis cystica profunda
Micro images: various images; erosion, ulceration, inflammation and regenerative change; prominent smooth muscle fibers; smooth muscle actin; associated sessile serrated polyps
DD: ulcers due to ergotamine suppositories, rectal endometriosis (Mod Path 1995;8:599), Cowden’s disease (same histology, different clinical features), mucinous adenocarcinoma (irregular mucin pools, epithelium floating in mucin, complex glandular proliferation, variable atypia, desmoplasia, usually no hemorrhage), ulcerative proctitis, Crohn’s disease
Also called angiodysplasia, arteriovenous malformation
Prevalence < 1%, but accounts for 20% of patients with lower GI bleeding
Often in elderly
Usually right colon, usually acquired
May be associated with aortic stenosis or von Willebrand disease
Bleeding is due to minimal number of cells between lumen and vessels
Endoscopic image: case associated with myelofibrosis
Case reports: associated with myelofibrosis (J Clin Pathol 2004;57:999), 22 year old woman (Indian J Pathol Microbiol 2006;49:34)
Treatment: electrocoagulation (Gastrointest Endosc 2006;64:424) or surgery
Gross: tortuous dilation of submucosal and mucosal blood vessels containing small amounts of smooth muscle; small, multiple, easier to identify by arteriography than in surgical specimen unless inject with silicone rubber and clear with methyl salicylate
Micro: dilated and thin walled vessels, often with cholesterol emboli, particularly in submucosa
Micro images: angiodysplasia #1; #2; #3; with secondary ulceration #1; #2; #3; ectatic mucosal blood vessels containing barium and submucosal thromboemboli (arrow); no ulceration or inflammation; ectatic submucosal veins
Virtual slides: angiodysplasia
DD: colonic varices due to portal hypertension
References: J Clin Pathol 1982;35:824, eMedicine
Common causes are polyarteritis, phlebitis, Churg-Strauss syndrome (Hepatogastroenterology 1997;44:1090), small vessel vasculitis (AJSP 1995;19:338), leukocytoclastic vasculitis (Wien Klin Wochenschr 2005;117:565, Dis Colon Rectum 2005;48:167)
Intramural phlebitis (enterocolic lymphocytic phlebitis)
May cause ischemic intestinal necrosis and resection (AJSP 1989;13:303)
Some cases associated with use of hydroxyethyl rutozide; others of unknown origin
No association with systemic vasculitis
Case reports: associated with flutamide (AJSP 2004;28:542), isolated mesocolic vasculitis (AJSP 2001;25:827), thickened serosal presenting as abdominal mass (J Clin Gastroenterol 2002;34:252)
Diagnostic criteria: predominantly lymphocytic infiltration of intramural tributaries of mesenteric veins
Micro: phlebitis affecting all layers of bowel wall, numerous associated thrombi; may have myointimal hyperplasia of affected mesenteric veins (AJSP 1994;18:779); arterioles and arteries not affected
Micro images: idiopathic enterocolic lymphocytic phlebitis #1; #2; #3
References: AJSP 2000;24:824, Mod Path 2000;13:897, USCAP Short Course
Complete twisting of loop of bowel around its mesenteric base of attachment, causing obstruction and infarction
Usually involves cecum or sigmoid (Can J Surg 2006;49:203)
Gangrene may extend beyond constriction (Int J Colorectal Dis 2004;19:134)
Treatment: surgical exploration to untwist and resect gangrenous bowel
Gross images: various images; sigmoid colon; intestine
References: eMedicine
Also called xanthoma, xanthomatous polyp, xanthogranulomatous inflammation
Very rare in colon; may clinically resemble polyp or carcinoma
Foamy cells without mucin
Foamy histiocytes common (40%) in rectal biopsies, but usually contain mucin (AJSP 2000;24:1009)
May be due to prior injury
Case reports: submucosal mass in sigmoid (Pathol Int 2005;55:440), intestinal xanthomas associated with xanthoma disseminatum (Dermatology 2004;208:164)
Micro: associated with surface hyperplastic change (APMIS 2004;112:3)
Positive stains: CD68
Negative stains: PAS-diastase, Alcian blue (pH 2.5 or 1.0), mucicarmine
DD: muciphages (positive mucin stains)
EM: electron-dense globules
