Gastrointestinal Pathology Evening Specialty Conference March 17, 2016 Laura W. Lamps, MD Professor and Vice Chair of Academic Affairs University of Arkansas for Medical Sciences Little Rock, AR

Clinical Summary 40 year old woman with HIV Undetectable viral loads for more than 15 years 15 month history of episodic nausea, vomiting, diarrhea Some episodes resolved spontaneously Others severe, requiring hospitalization for dehydration

Clinical Summary Patient originally from Ethiopia, occasionally traveled there Lived in Western US for many years Symptoms do not correlate with travel Previous EGD/colonoscopy normal x2; normal capsule endoscopy

Clinical Summary Laboratory Data Peripheral eosinophilia Stool O&P repeatedly negative Positive Strongyloides antibody; all other infectious disease serologies negative

Diagnosis: Cystoisosporiasis

Cystoisosporiasis Cystoisospora belli (formerly Isospora belli) Obligate intracellular coccidian parasite with worldwide distribution Especially common in tropical/subtropical climates Ubiquitous in animal kingdom Transmission through food, water

Cystoisosporiasis Originally described in soldiers during WWI and WWII Rare in USA prior to AIDS epidemic Prevalence in Western countries ~ 5% Prevalence in developing countries ~10-15%

Cystoisosporiasis Life cycle Complex to say the least Ingestion, followed by excystation and invasion Asexual division produces more organisms that infect more cells Some enter the sexual phase, develop male and female gametes, fertilization occurs, oocysts released into the lumen Sexual forms can autoinfect or pass in the stool to continue the cycle

Cystoisospora Life Cycle http://www.cdc.gov/dpdx/cystoisosporiasis/

Cystoisosporiasis Clinical Immunocompetent patients Typically asymptomatic diarrheal infections Immune compromised patients Watery nonbloody diarrhea, dehydration Abdominal pain Nausea, vomiting Fever, malaise

Cystoisosporiasis Clinical Infection more severe in immunocompromised patients Severe malabsorption, dehydration, cachexia, dissemination Many cases respond to antiobiotics (Bactrim), so important to recognize infection

Cystoisosporiasis Clinical Peripheral eosinophilia common Charcot-Leyden crystals may be seen in stool EGD/colonoscopy usually normal Occasionally mild erythema Stool studies Usually not helpful unless special stains requested

Variably present villous blunting, surface disarray, increased IELs Eosinophils usually prominent in GI specimens but not biliary

Parasitophorous vacuole is characteristic

PAS

Giemsa

Cystoisospora Biliary infection Symptomatic cholangitis, typically in AIDS patients Reported in gallbladders from liver donors, cholecystectomy for biliary dyskinesia in otherwise healthy patients Often minimal tissue reaction

Courtesy Dr. Keith Lai

Diagnosis Light microscopy Stool O&P PCR from stool Sensitivity/specificity variable depending on technique (40-100%; 88-100%) Acid fast stains, antigen detection techniques PCR from stool 87-100% sensitivity; 88-100% specificity

Differential Diagnosis Other things that cause villous blunting +/- eosinophils Celiac disease Idiopathic eosinophilic enteritis Adverse drug effect Food allergy

Idiopathic eosinophilic enteritis

Olmesartan toxicity

Differential Diagnosis Other coccidians Other intracellular organisms Will almost always be within macrophages, and not at the luminal surface of the epithelium Leishmania Toxoplasmosis Fungi (Histoplasmosis, P. marneffei)

Comparison of Enteric “Coccidians*” Feature Microsporidia Cryptosporidia Cyclospora Cystoisospora Size 2-3µ (smallest) 2-5 µ 2-3µ schizonts 5-6µ merozoites 15-20µ (largest) Location Epithelial cells Apical surface Upper epithelium Epithelium Macrophages Staining Mod trichrome Giemsa Gram W-S PAS Acid fast Auramine GMS Other Birefringent under polarized light Bulges out of luminal apex of enterocyte Parasitophorous vacuole Eosinophils *Microsporidia are now classified as fungi *Cryptosporidia are still parasites, but Gregorines, not coccidia

Cryptosporidium

Microsporidia

Modified trichrome stain highlights organisms

Cyclospora: surface epithelial cell disarray Case and pictures courtesy of Dr. Rhonda Yantiss

Round schizonts and banana shaped merozoites in parasitophorous vacuoles

Differential Diagnosis Other coccidians Other intracellular organisms Will almost always be within macrophages, and not at the luminal surface of the epithelium Leishmania Toxoplasmosis Fungi (Histoplasmosis, P. marneffei)

P. marneffei

Histoplasmosis

Summary/Take Home Cystoisospora is the largest coccidian, but easily missed Associated histologic findings may be subtle, so remember to look for them They are treatable with antibiotics Not limited to immunocompromised patients Stool studies can be helpful