Eosinophilic Cholecystitis

 Probably not distinct entity, but rather descriptive designation with associated clinical correlates

Etiology/Pathogenesis

• Majority of cases have no known cause or disease association

• Some associated with hypersensitivity reactions, parasitic infection, other eosinophilic diseases

 Hypersensitivity reaction to bile and bile stones has been hypothesized but never proven

Microscopic

• Dense eosinophilic infiltrate of gallbladder ± lymphocytic inflammatory component

 Typically > 50% of inflammatory infiltrate is composed of eosinophils

 So-called lymphoeosinophilic cholecystitis shows significant component of lymphocytes as well

 In “true” or “pure” eosinophilic cholecystitis, close to 100% of inflammatory component is composed of eosinophils

• Specimen should be carefully evaluated for parasites

TERMINOLOGY

Abbreviations

• Eosinophilic cholecystitis (EC)

Definitions

• Inflammatory disease of gallbladder in which inflammatory infiltrate is composed predominantly of eosinophils

 Some advocate for reserving this term for cases in which infiltrate is purely eosinophilic

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 Probably not distinct entity, but rather descriptive designation with some associated clinical correlates

ETIOLOGY/PATHOGENESIS

No Specific Cause in Most Cases

• Hypersensitivity reaction to bile and bile stones has been hypothesized but never proven

• Some cases associated with hypersensitivity reaction to drugs, infections ( Echinococcus, Clonorchis sinensis )

• Some cases associated with other eosinophilic diseases

 Eosinophilic gastroenteritis, eosinophilic cholangitis, hypereosinophilic syndrome

• Majority of cases have no specific underlying cause or disease association

CLINICAL ISSUES

Presentation

• Presenting signs are similar to other forms of acute and chronic cholecystitis

 Right upper quadrant pain, biliary colic

• Peripheral eosinophilia

 Frequently but not invariably present

• Typically acalculous cholecystitis

 Although calculi are sometimes seen, stones are less commonly seen in EC than in other forms of acute and chronic cholecystitis

Treatment

• Cholecystectomy

 Diagnosis is invariably made following evaluation of gallbladder specimen

• In rare instances when preoperative diagnosis has been made, steroid therapy is reported to be effective

Prognosis

• Cholecystectomy is curative, and disease does not recur

MICROSCOPIC

Histologic Features

• Thickened and inflamed gallbladder wall

 Predominantly eosinophilic infiltrate

– Typically > 50% of inflammatory infiltrate is composed of eosinophils

– Sheets and clusters of eosinophils infiltrate mucosa, muscularis propria, and subserosa

– Inflammation may preferentially involve one layer of gallbladder wall, or may be transmural

• Variations

 In “true” or “pure” EC, close to 100% of inflammatory component is composed of eosinophils

– More rare than lymphoeosinophilic form

 So-called lymphoeosinophilic cholecystitis shows significant component of lymphocytes as well

DIFFERENTIAL DIAGNOSIS

Chronic Cholecystitis

• Subacute phase of acute cholecystitis may show significant tissue eosinophilia

• Dense sheets and significant clustering of eosinophils are not seen in chronic calculous cholecystitis

Acute and Subacute Cholecystitis With Cholelithiasis

• Frequent admixture of neutrophils and eosinophils, particularly in instances of acute cholecystitis in which cholecystectomy is delayed

• Eosinophils do not typically dominate infiltrate, however

Autoimmune Pancreatitis-Associated Cholecystitis

• Gallbladder inflammation associated with autoimmune pancreatitis is dominated by lymphocytes and plasma cells

 Can show significant numbers of eosinophils

• Elevated numbers of IgG4(+) plasma cells help distinguish this entity from EC

Churg-Strauss Syndrome

• EC lacks significant vascular infiltration by eosinophils, and should not have vascular damage

DIAGNOSTIC CHECKLIST

Pathologic Interpretation Pearls

• Predominance of eosinophils in inflamed gallbladder

• Variably present gallstones

• May be associated with other eosinophilic diseases or peripheral eosinophilia

 Most cases have no specific disease association

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Diagnostic Pathology Hepatobiliary and Pancreas