A case of eosinophilic cholecystitis: Radiologic-pathologic correlation

Abstract

Eosinophilic cholecystitis (EC) is a rare condition that is characterized by eosinophilic infiltration in the gallbladder wall. We report the case of a 35-year-old woman who presented with unremitting right upper quadrant pain for 1 month. Computed tomography showed a strongly enhanced inner layer of the gallbladder wall. Magnetic resonance imaging of the same area showed low signal intensity on T2-weighted imaging. Cholecystectomy was performed, and histological examination of the surgical specimen revealed >100 eosinophils per high-power field in the inner subserosal layer. The area of these histological findings corresponded to the strongly enhanced inner layer of the gallbladder wall identified on computed tomography.

Introduction

Eosinophilic cholecystitis (EC) is a rare condition that is characterized by eosinophilic infiltration in the gallbladder wall and was first reported by Albot et al. in 1949 [1]. Previous reports of EC focused on the clinical or pathological findings; few reports have highlighted the correlation between imaging findings and pathologic findings in EC. We report a rare case of EC with diffuse marked gallbladder wall thickening caused by eosinophilic infiltration that was identifiable both radiologically and pathologically.

Case report

A 35-year-old woman presented to our hospital with occasional right upper quadrant pain for 5 years that had become continuous for 1 month. No apparent abnormalities were observed in blood laboratory tests, including inflammatory and tumor markers.

Plain computed tomography (CT) demonstrated marked gallbladder wall thickening (Fig. 1A). The maximum width of the thickened gallbladder wall was 30 mm. The arterial phase on dynamic contrast-enhanced CT demonstrated a slight contrast effect in the prominent inner layer of the thickened gallbladder wall (Fig. 1B), with a gradual contrast effect from the portal venous phase to the equilibrium phase (Figs. 1C and D).

Fig. 1.

Computed tomographic findings. (A) Plain CT image showing marked gallbladder wall thickening (arrowhead). (B) Dynamic contrast-enhanced CT image during the arterial phase showing a slight contrast effect in the prominent inner layer of the thickened gallbladder wall (arrow). (C, D) Dynamic contrast-enhanced CT images from the portal phase to the equilibrium phase showing a gradual contrast effect in the prominent inner layer of the thickened gallbladder wall (arrow in each image).

CT, computed tomography.

T2-weighted (T2WI) magnetic resonance imaging (MRI) showed a low signal intensity in the inner layer and high signal intensity in the outer layer of the thickened gallbladder wall (Fig. 2A). Diffusion-weighted imaging showed slightly high signal intensity in the inner layer of the thickened gallbladder wall (Fig. 2B). No gallstones were observed.

Fig. 2.

Magnetic resonance imaging findings. (A) T2-weighted image showing a low-signal-intensity area in the inner layer of the thickened gallbladder wall (arrow). (B) Diffusion-weighted magnetic resonance image showing high signal intensity in the inner layer of the thickened gallbladder wall (arrow).

The inner layer of the thickened gallbladder wall showed a gradual contrast effect on dynamic contrast-enhanced CT and low signal intensity on T2WI MRI, suggesting the presence of abundant fibrous and granulomatous components. The preoperative differential diagnoses were xanthogranulomatous cholecystitis, adenomyomatosis of the gallbladder, and gallbladder cancer.

Laparoscopic cholecystectomy was performed, and surgical exploration revealed marked gallbladder wall thickening and mild adhesion to the surrounding tissues (Fig. 3).

Fig. 3.

Macroscopic findings. Surgical exploration revealed marked gallbladder wall thickening, with mild adhesion to the surrounding tissue. No gallstones were observed.

Microscopic examination with hematoxylin and eosin staining (Fig. 4A: × 40 magnification, Fig. 4B: × 400 magnification) revealed that the thickened section of the gallbladder wall comprised mainly the subserosal layer. This layer was divided into 2 layers: the inner subserosal layer, which was markedly infiltrated with inflammatory cells, including a high eosinophilic infiltration, and the outer subserosal layer, which had marked edematous changes. More than 100 eosinophils were identified per high-power field within the inner subserosal layer, and the pathologic diagnosis was EC.

Fig. 4.

Pathologic findings. (A) Photomicrograph (hematoxylin and eosin, × 40 magnification) showing that the gallbladder wall thickening comprised mainly the subserosal layer. This layer was divided into 2 layers: the inner subserosal layer, markedly infiltrated with inflammatory cells, including high numbers of eosinophils, and the outer subserosal layer, with marked edematous changes. (B) Photomicrograph (hematoxylin and eosin, × 400 magnification) showing >100 eosinophils per high-power field in the inner subserosal layer.

Discussion

To our knowledge, this is the first case of EC presenting as a diffusely thickened gallbladder wall caused by eosinophilic infiltration in which it was possible to compare the pathological findings with findings on contrast-enhanced CT and MRI. There have been no comprehensive reports on imaging findings for EC because of its rarity.

EC is a subtype of chronic cholecystitis. Memis et al. analyzed the pathology in 1050 cases of cholecystitis, namely 55 cases of acute cholecystitis, 100 cases of subacute cholecystitis, and 895 cases of chronic cholecystitis [2]. Ten cases of cholecystitis with >100 eosinophils per high-power field were classified as EC, and all EC cases were in the chronic cholecystitis group. The patient in the present case had been symptomatic for more than 5 years, with no elevated inflammatory markers on blood laboratory testing and a chronic clinical course similar to that with chronic cholecystitis.

In a report of 22 cholecystectomies for EC by Khan et al. [3], 91% had gallstones, 18% had a history of allergy, and 9% had peripheral blood eosinophilia. Our patient had none of these findings.

In a report of 10 cases of EC by Memis et al. the mean gallbladder wall thickening measured 3.5 mm [2]. Our patient had greater gallbladder wall thickening compared with cases in previous reports. The inner subserosal layer showed gradual enhancement on contrast-enhanced CT and low signal intensity on T2WI MRI, reflecting inflammatory cell infiltration and associated fibrosis. The outer subserosal layer showed a weak contrast effect on contrast-enhanced CT and high signal intensity on T2WI MRI, reflecting edematous changes.

Gallbladder wall thickening in EC is composed of a marked eosinophilic infiltration. Fox et al. [4] reported 16 cases of EC in which 18.8% (3/16) had eosinophilic infiltration in the mucosal layer and 81.2% (13/16) had eosinophilic infiltration in the muscular and subserosal layers. In comparison, Khan et al. [3] reported 22 cases of EC in which 72.7% (16/22) had eosinophilic infiltration in the mucosal and muscular layers, 27.2% (6/22) had eosinophilic infiltration in the muscular layer, and no cases had eosinophilic infiltration in the subserosal layer. The eosinophilic infiltration in the present case was mainly in the inner subserosal layer. Considering the present case and previously reported cases, eosinophilic infiltration on EC can occur in the mucosal, muscular, or subserosal layer.

It is difficult to differentiate EC and malignancy on the basis of imaging. Kim et al. used contrast-enhanced CT to study its diagnostic ability to differentiate benign from malignant tumors in cases of thickened gallbladder walls [5]. The authors classified the contrast effect in the gallbladder wall into 5 patterns (type 1 is a 1-layer pattern, and types 2–5 are 2-layer patterns). Type 1 comprised 1 layer of heterogeneously contrasted gallbladder wall or indistinguishable stratification of the gallbladder wall. Type 2 comprised a thick inner layer that was strongly contrasted and an outer layer that was weakly contrasted or noncontrasted. The common enhancement patterns for gallbladder cancer were the type 1 and 2 patterns. The findings in the present case met the criteria for type 2, but without malignancy. Additional cases are needed to investigate the contrast pattern of the gallbladder wall in contrast-enhanced CT in patients with EC.

In conclusion, we reported a case of EC with marked gallbladder wall thickening in which we compared the imaging and pathologic findings. In this case of EC, marked eosinophilic infiltration and fibrosis within the thickened gallbladder wall were identified as a gradual contrast effect on CT and low signal intensity on T2WI MRI. In comparison, edematous changes were identified as a weak contrast effect on CT and high signal intensity on T2WI MRI.

Patient consent

Written informed consent was obtained from the patient for publication of this case.