R J M E Romanian Journal of Morphology & Embryology

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1 Rom J Morphol Embryol 2017, 58(3): ORIGINAL PAPER R J M E Romnin Journl of Morphology & Embryology Eosinophilic colitis: experience in lrge tertiry hospitl CRISTINA DÍAZ DEL ARCO 1), CARLOS TAXONERA 2), LOURDES ESTRADA MUÑOZ 1), DAVID OLIVARES 2), MARÍA JESÚS FERNÁNDEZ ACEÑERO 1) 1) Deprtment of Surgicl Pthology, Hospitl Clínico Sn Crlos, Mdrid, Spin 2) Deprtment of Gstroenterology, Hospitl Clínico Sn Crlos, Mdrid, Spin Abstrct Bckground: Eosinophilic colitis (EC) is rre nd ill-defined entity with n unknown pthogenesis nd n unstisfctory tretment response. The stndrd histopthologicl criteri for EC dignosis lck specificity nd not ll the cses fulfilling those criteri re considered cliniclly s EC nd treted. The objective of this study is to refine dignostic criteri for EC. Methods: Retrospective study of ll the cses with histopthologicl dignosis of EC in Hospitl Clínico Sn Crlos (Mdrid, Spin) from 2006 to We hve reviewed their clinicl nd pthologicl fetures nd tried to define the fetures differentiting cses considered EC on clinicl grounds. Results: We identified 106 EC cses. In 22 cses, clinicl EC dignosis ws estblished. Confirmed EC ws ssocited with younger ge, femle gender, dirrhe, higher mximum number of eosinophils/hpf (high-power field), intrepithelil eosinophils, rchitecturl distortion nd bsence of cute inflmmtion. We chose cut-off point of 40 for both men nd mximum number of eosinophils/hpf. A men number of eosinophils/hpf higher thn 40 ws relted to rchitecturl distortion, mucosl trophy, signs of eosinophil ctivtion nd submucosl infiltrtion. Cses with mximum number of eosinophils/hpf higher thn 40 showed more rchitecturl distortion, intrepithelil eosinophils, submucosl infiltrtion nd lck of lymphoplsmcytic infiltrtion. Conclusions: Histopthologicl dignosis of EC is not well correlted with clinicl EC. An increse in specificity cn be chieved by rising the cut-off point to 40 eosinophils/hpf nd by combining men nd mximum number of eosinophils with other microscopic nd clinicl fetures suggestive of EC. Keywords: eosinophilic, colitis, eosinophil, lrge, bowel. Introduction Eosinophils re inflmmtory cells with beneficil nd dverse effects. They exert ntiprsitic, ntivirl nd ntibcteril effects nd re involved in innte nd dptive immune responses [1]. Besides, they ply mjor role in certin pthologies, such s sthm, eczem, vsculitis or hypereosinophilic syndrome [2, 3]. Some uthors hve demonstrted dysfunction of the epithelil brrier nd n increse in fibroblstic prolifertion nd collgen production medited by eosinophils in the gstrointestinl (GI) trct, both in culture models nd GI disorders [3, 4]. Eosinophils re normlly present in the GI trct, with the exception of the esophgus. They re found in the lmin propri, nd their occurrence in this loction is regulted by cytokines nd chemokines, such s interleukin-3 (IL-3), IL-5 or eotxin-3. These molecules lso modify eosinophil survivl, degrnultion nd development in the bone mrrow [5 7]. In the norml lrge bowel, there is non-pthologicl inflmmtory infiltrte comprised of lymphocytes, plsm cells, eosinophils (3% of ll inflmmtory cells) nd smll number of mcrophges nd mst cells [8]. It is known tht there is grdient in the number of eosinophils in the lrge intestine: they re supposed to decrese from proximl to distl regions [9]. However, there is no consensus bout their norml rnge. In fct, uthors hve reported numbers rnging from eosinophils per high-power field (HPF) in cecum to 1 30 eosinophils (HPF) in rectum [10]. Eosinophilic GI diseses hve n incresing prevlence nd re subdivided in eosinophilic esophgitis (EE), gstritis, colitis (EC) or gstroenteritis, depending on the region of the GI trct involved [7, 11]. EE is the best known of these diseses, with n estblished cut-off point of 15 eosinophils/hpf nd other dignostic criteri like the presence of microbscesses or the ltertion of eosinophil mucosl distribution [12]. In respect of the lrge intestine, llergic proctocolitis nd food-protein induced enterocolitis syndrome hve been recognized in infnts nd children [13]. However, EC in dults is rre nd ill-defined condition with n unknown pthogenesis nd n unstisfctory tretment response [11]. The stndrd histopthologicl criteri for EC dignosis lck specificity nd not ll the cses fulfilling those criteri re considered cliniclly s EC nd treted. The objective of this study is to refine dignostic criteri for EC. Ptients, Mterils nd Methods This is retrospective cliniclly-bsed study of the cses with histopthologicl dignosis of EC in lrge tertiry hospitl (Hospitl Clínico Sn Crlos) in Mdrid, Spin. We hve included ll the cses histopthologiclly dignosed of EC between In this time period, totl of 106 lrge bowel biopsies were reported s lrge intestine mucos with EC following the stndrd criterion of more thn 20 eosinophils/hpf s stted in the literture. Specimens were formlin-fixed nd prffin-embedded, sectioned to 5-μm thickness nd stined with Hemtoxylin nd Eosin (HE). Neither histochemicl nor immunohistochemicl techniques were performed. These cses were retrospectively reviewed by two independent pthologists to confirm dignosis. Microscopic findings, such s number of totl frgments per biopsy, number of involved frgments ISSN (print) ISSN (online)

2 784 per biopsy, men eosinophil count per HPF, mximum eosinophil count per HPF, loction nd distribution of eosinophils, signs of eosinophil ctivtion (eosinophilic bscesses, intrepithelil eosinophils, extensive degrnultion), rchitecturl distortion, mucosl trophy, fibrosis, loss of epithelil mucin, presence of cute inflmmtion (cryptitis nd/or microbscesses), lymphoplsmcytic infiltrtion nd lymphoid folliculr hyperplsi were ssessed. Men number of eosinophils per HPF ws clculted by counting eosinophils in five HPF in hot spots with the highest number of eosinophils. Mximum number of eosinophils per HPF ws obtined from the HPF which contined the highest number of eosinophils. With this im, we hve used Leic microscope with field re of 0.18 mm 2 per HPF. Medicl records were lso reviewed nd demogrphic nd endoscopic dt were collected for the study, including ge, gender, inflmmtory bowel disese (IBD) dignosis, food llergies, history of eosinophil-relted diseses (sthm, dermtitis, scleroderm, dermtomyositis, polymyositis, hypereosinophilic syndrome), other GI disorders, regulr mediction (eosinophil-relted drugs, such s chronic non-steroidl nti-inflmmtory drugs (NSAIDs), clozpine, crbmzepine, tcrolimus, gold slts), dirrhe, severity of dirrhe (N1 dirrhe: 1 2 stools bove norml per dy; N2 dirrhe: 3 4 stools bove norml per dy; N3 dirrhe: five or more stools bove norml per dy), other clinicl symptoms (rectl bleeding, weight loss, mlbsorptive or obstructive symptoms, mlnutrition, scites) nd presence of prsitic infections. Blood tests close in time to the biopsy smpling nd endoscopic records were lso reviewed, nd we recorded the percentge of eosinophils in peripherl blood. Although ll the ptients fulfilled histopthologicl criteri of EC in the biopsies, not ll of them hd been considered EC cses nd treted ccordingly on clinicl grounds. With the im of defining more specific histopthologicl criteri to define this entity, we hve compred the histopthologicl fetures of these ptients to those who were not considered clinicl EC. The clinicl nd pthologicl fetures chosen for evlution were extrpolted from the previous literture nd they were lso consensul decision between the pthologists nd clinicins involved in this study. Sttisticl nlysis All the informtion hs been nlyzed with the SPSS 20.0 for Windows sttisticl pckge. For the nlysis of ssocition between vribles, we hve employed either χ 2 (chi)-squred test (qulittive vribles) or Student s t-test (to compre mens between dichotomic quntittive vribles). For the im of the present study, the sttisticl significnce ws settled t p-vlue <0.05. The cut-off vlue for continuous quntittive vribles hs been estblished with receiver opertor curve (ROC) nlysis. All the dt hve been obtined from the institutionl electronic helth record nd dtbse of Deprtment of Surgicl Pthology (PtWin). Ethicl considertions The study ws pproved by the Ethicl Committee of the Hospitl, nd the dt hve been stored nd nlyzed in n nonymized dtbse to fulfill the requirements of the Spnish lws regrding personl dt protection. Cristin Díz Del Arco et l. Informed consent ws not necessry due to the design of our study (nonymized retrospective cse series). Results One hundred nd six cses of ptients with histopthologicl dignosis of EC were identified in the 10- yer period of enrollment. Clinicl fetures of ll cses re summrized in Tble 1. Tble 1 Clinicl fetures of ptients with eosinophilic infiltrtion of the bowel wll (n=106) Age (men, yers) 50 Gender M: 46 (43.4%); F: 60 (56.6%) Inflmmtory bowel 10 (9.4%) disese (IBD) b UC: 7 (6.6%); CD: 3 (2.8%) Food llergy 3 (2.8%) Eosinophil-relted 9 (8.5%) diseses Asthm: 7 (6.6%) Hypereosinophilic syndrome: 1 (0.94%) Kimur disese: 1 (0.94%) GI disorders Fmilil denomtous polyposis (FAP): 7 (6.6%) Colonic denocrcinom: 6 (5.6%) Drugs 3 (2.83%) Chronic use of NSAIDs: 2 (1.9%) Sulfslzine: 1 (0.94%) Dirrhe 70 (66%) Rectl bleeding 12 (11.3%) Other symptoms Weight loss: 3 (2.8%) Obstructive symptoms: 1 (0.94%) Mlbsorptive symptoms: 1 (0.94%) Incidentl finding 23 (21.7%) Prsitic infection Peripherl blood eosinophili Endoscopic findings (dt vilble in 98 pts.) 7 (6.6%) Aniskis: 5 (4.71%) Fsciol: 1 (0.94%) Strongyloides: 1 (0.94%) 14 (13.2%) No lesions: 71 (68.9%) Non-specific colitis: 15 (14.5%) IBD: 11 (10.6%) Comptible with EC: 1 (1%) M: Mle, F: Femle; b UC: Ulcertive colitis, CD: Crohn disese; NSAIDs: Non-steroidl nti-inflmmtory drugs; IBD: Inflmmtory bowel disese; EC: Eosinophilic colitis. Men ge ws 50 yers nd 60 (56.6%) ptients were women. Ten (9.4%) ptients hd previous dignosis or were subsequently dignosed s IBD. Only three (2.8%) ptients referred food llergies. In regrd of diseses ssocited with eosinophili, seven (6.6%) ptients hd sthm, one ptient (0.94%) hd hypereosinophilic syndrome nd one ptient (0.94%) hd Kimur disese. In two (1.9%) ptients, chronic use of NSAIDs ws documented nd one ptient (0.94%) ws tking meslzine. In 23 (21.7%) cses, EC ws n incidentl finding, while 70 (66%) ptients presented with dirrhe, the most common presenting symptom. Severity of dirrhe ws recorded in 59 ptients: nine ptients hd N1 dirrhe, 20 ptients hd N2, nd 30 ptients hd N3 dirrhe. Other consulting symptoms found in our review were rectl bleeding (12 cses, 11.3%), weight loss (three cses, 2.8%), obstructive symptoms (one cse, 0.94%) or mlbsorptive symptoms (one cse, 0.94%). Fourteen (13.2%) ptients hd peripherl blood eosinophili (PBE), nd in seven (6.6%) ptients, prsitic infection ws detected. Two ptients were lso dignosed with EE nd eosinophilic gstritis.

3 Eosinophilic colitis: experience in lrge tertiry hospitl Endoscopic dt were vilble in 103 (97.2%) ptients. Endoscopic studies reveled norml intestinl mucos in 71 (68.9%) ptients, non-specific colitis in 15 (14.56%) ptients, IBD fetures in 11 (10.67%) ptients nd EC fetures in one cse (0.97%). Microscopic findings of the endoscopic biopsies re summrized in Tble 2. Tble 2 Histologicl fetures of ptients with eosinophilic infiltrtion of the bowel wll (n=106)* Totl biopsy frgments Involved frgments Men number of eosinophils b per HPF Mximum number of eosinophils per HPF Level of infiltrtion in the bowel wll Architecturl distortion Mucosl erosion Pneth cell metplsi Mucosl trophy Fibrosis Decrese of mucin c Signs of eosinophil ctivtion Acute inflmmtion Lymphoid folliculr hyperplsi Lymphoplsmcytic infiltrtion 4.96 (min.: 1, mx.: 13) (min.: 7, mx.: 199) (min.: 10, mx.: 253) Eosinophils minly in lmin propri in ll cses Homogeneous distribution: 59 (55.7%) Minly superficil: 40 (37.7%) Submucosl infiltrtion: 7 (6.6%) 71 (66.98%) 6 (5.7%) 6 (5.7%) 17 (16%) 44 (41.5%) 19 (17.9%) EA: 15 (14.2%) IE: 71 (67%) ED: 43 (40.6%) 17 (16%) 25 (23.6%) 28 (26.4%) min.: Minimum, mx.: Mximum; bhpf: High-power field; cea: Eosinophilic bscesses, IE: Intrepithelil eosinophils, ED: Extensive degrnultion. *All quntittive vribles re expressed s men. The number of frgments per biopsy rnged from one to 13 (men: 4.96), nd men of 3.26 of them were involved. Eosinophils were infiltrting the lmin propri in ll cses, with homogeneous distribution in 59 (55.7%) cses, superficil mucosl involvement in 40 (37.7%) cses nd submucosl infiltrtion in seven (6.6%) cses. However, ssessment of submucosl infiltrtion ws not relible, becuse most endoscopic biopsies did not Figure 1 (A) Colonic mucos showing rchitecturl distortion; (B) Crypt distortion with loss of epithelil mucin. HE stining: 100 (A); 200 (B). 785 include the submucos. For this reson, musculris propri or serosl involvement could not be ssessed. Men number of eosinophils per HPF rnged from seven to 199 (men: 43.2), nd mximum number of eosinophils per HPF rnged from 20 to 253 (men: 55.16). The most frequent microscopic findings were rchitecturl distortion (71 cses, 66.98%), intrepithelil eosinophils (71 cses, 66.98%), extensive eosinophil degrnultion (43 cses, 40.6%) nd fibrosis (44 cses, 41.5%) (Figures 1 3). None of our cses fulfilled criteri of microscopic colitis (either lymphocytic or collgenous colitis). Twenty-two of 103 (21.3%) ptients were cliniclly considered EC, nd 18 (81.8%) of these ptients were treted. Phrmcologicl tretment ws prescribed in 12 (54.5%) ptients: corticosteroids in five cses, budesonide in four cses, meslzine in two cses nd colchicine in one cse. In three (13.63%) ptients, dietry modifictions were prescribed, nd in three (13.63%) ptients, combined dietry nd phrmcologicl tretment ws recommended. Tretment response ws recorded in 15 (68.1%) ptients, with tretment response rte of 86.6% (13 ptients). The remining ptients were not considered cliniclly suggestive of EC despite histopthologicl findings nd none of them were treted. All hve been followed-up on the long term, with no recurrence of symptoms. We hve compred EC nd non-ec ptients nd results re summrized in Tble 3. Sttisticl nlysis showed tht EC ptients were significntly younger (p=0.042, men: 22 yers) thn non-ec ptients (men: 84 yers). We lso observed trend towrds significnce for the ssocition between EC nd femle gender (p=0.087), nd presence of dirrhe (p=0.058). EC ws more often ssocited with peripherl blood eosinophili (p=0.024). Endoscopic findings showed no sttisticlly significnt differences between groups. With regrd to microscopic findings, mximum number of eosinophils per HPF ws higher in EC ptients (men: 73) thn in non-ec ptients (men: 50), lthough this difference did not rech sttisticl significnce (p=0.072). Men number of eosinophils per HPF did not show sttisticlly significnt differences between groups, lthough it ws higher in EC ptients (55.8 vs. 39.9, p=0.116). We observed trend towrds significnce for the ssocition between EC nd presence of intrepithelil eosinophils (p=0.096) nd bsence of cute inflmmtion (p=0.99) nd rchitecturl distortion (p=0.072). Figure 2 (A) Mucosl trophy: Mild reduction in the number of crypts; (B) Fibrosis of the lmin propri. HE stining, 100 (A nd B).

4 Cristin Díz Del Arco et l. 786 nd extensive eosinophil degrnultion. Lymphoid folliculr hyperplsi ws detected more frequently in cses with men number of 40 eosinophils per HPF. Cses with mximum number of 40 eosinophils/ HPF were more often ssocited with the presence of lymphoplsmcytic infiltrtion (p=0.027). A trend towrds significnce ws seen in the ssocition between cses with mximum number of >40 eosinophils/hpf nd level of eosinophilic infiltrtion in the bowel wll, rchitecturl distortion or intrepithelil eosinophils. Tble 4 Ptients with cliniclly confirmed eosinophilic colitis: sttisticl differences between groups fter estblishing cut-off vlue for the men number of eosinophils/hpf of 40* Feture Architecturl distortion Tble 3 Summry of the differences between cliniclly confirmed EC ptients (n=22) nd non-ec ptients (n=84)* Feture Age (yers) Mximum number of b eosinophils per HPF Men number of eosinophils per HPF Femles Dirrhe Peripherl blood eosinophili Architecturl distortion Intrepithelil eosinophils Acute inflmmtion Vlues in both groups EC: 22, NEC: 84 P vlue for the ssocition EC: 73, NEC: EC: 55.8, NEC: 39.9 EC: 72%, NEC: 52% EC: 86.3%, NEC: 63% EC: 27%, NEC: 9.5% EC: 14.2%, NEC: 33.3% EC: 81.8%, NEC: 63% EC: 44.5%, NEC: 19% 0.09 EC: Eosinophilic colitis ptients, NEC: Non-eosinophilic colitis ptients; HPF: High-power field. All quntittive vribles re expressed s men. *We hve included both significnt differences (p<0.05) nd trend to significnce (p<0.1). b We chose cut-off point of 40 eosinophils per HPF in the ROC curve for both men nd mximum number of eosinophils per HPF nd we subsequently subdivided EC group into cses with 40 eosinophils/hpf nd cses with >40 eosinophils/hpf. Results of the comprison between groups re summrized in Tbles 4 nd 5. The presence of men number of >40 eosinophils/ HPF ws ssocited with rchitecturl distortion (p=0.032), submucosl infiltrtion (p=0.007), nd presence of cute inflmmtion (p=0.027). Cses with men number of >40 eosinophils/hpf showed more often mucosl trophy, intrepithelil eosinophils, eosinophilic microbscesses Tble 5 Ptients with cliniclly confirmed eosinophilic colitis: sttisticl differences between groups fter estblishing cut-off vlue for the mximum number of eosinophils/hpf of 40* Feture A: Cses with more thn 40 eosinophils/hpf, B: Cses with 40 or less eosinophils/hpf; HPF: High-power field. *We hve included both significnt differences (p<0.05) nd trend to significnce (p<0.1) A: 41.8%, B: 22% P vlue for the ssocition All cses with submucosl infiltrtion were group A cses Acute inflmmtion A: 25.58%, B: 9.5% Mucosl trophy A: 23.2%, B: 11.1% Intrepithelil eosinophils A: 76.7%, B: 60.3% Eosinophilic microbscesses A: 20.9%, B: 9.5% Extensive degrnultion A: 51.56%, B: 33.3% Lymphoid folliculr A: 16.3%, hyperplsi B: 31.7% Level of infiltrtion in the bowel wll Figure 3 (A) Eosinophil ctivtion: Eosinophilic microbscess; (B) Eosinophil ctivtion: Infiltrtion of the surfce epithelium nd crypts by eosinophils. HE stining, 200 (A nd B). Vlues in both groups Lymphoplsmcytic infiltrtion Level of infiltrtion in the bowel wll Architecturl distortion Intrepithelil eosinophils Vlues in both P vlue for the groups ssocition A: 18.75%, B: 38% All cses with submucosl infiltrtion were group A cses A: 36%, 0.1 B: 21% A: 73.4%, B: 57% A: Cses with more thn 40 eosinophils/hpf, B: Cses with 40 or less eosinophils/hpf; HPF: High-power field. *We hve included both significnt differences (p<0.05) nd trend to significnce (p<0.1). Discussion Some uthors suggest tht food llergens my ply key role in the pthogenesis of EE. History of topy is documented in 50 90% of cses nd food ntigens re the most frequently detected cuse of EE [14, 15]. Thus, EE is supposed to be n topic disorder medited by type 2 T-helper lymphocytes (Th2) [11]. EC is, nonetheless, deficiently studied disese nd its pthogenesis is unknown. Most cses in infncy re relted to food llergens, cusing llergic proctocolitis. Th2 is thought

5 to ply key role in the development of dult cses too, but the possible triggering fctors hve not been identified [16, 17]. In generl, mny disorders hve been relted to GI eosinophili, including food llergy, sthm, dermtitis, scleroderm, dermtomyositis, polymyositis, hypereosinophilic syndrome, prsitic infections or drug-induced colitis. EC hs lso been shown to be more frequent in topic ptients [8]. In our study, only three ptients with cliniclly dignosed EC were sthmtic nd none of them hd history of food llergy. Thus, we hve not been ble to confirm this lleged sttisticlly significnt ssocition between EC nd food llergy or diseses ssocited with eosinophili. EC hs bimodl ge distribution. It occurs minly in infnts nd young dults, lthough cses in older ptients hve been reported [18]. This predilection for the younger group hs lso been confirmed in the present study. We hve found trend towrds significtion between the ssocition between femle gender nd EC, but previous studies hve shown no gender predilection [8]. The signs nd symptoms of EC vry depending on the lrge bowel region involved by the disese nd the depth of bowel wll involvement. Klein et l. subdivided eosinophilic gstroenteritis into three min subtypes: mucosl, trnsmurl nd serosl EC (in descending order of frequency) [19]. In mucosl EC, eosinophils re locted in the superficil spect of the mucos nd the ptients present with mlbsorption, protein loss nd dirrhe [20]. If the infiltrte involves the musculris propri the clinicl symptoms re bowel obstruction, volvultion, intussusception nd thickening of the bowel wll. An intestinl perfortion my occur [21]. Serosl EC presents with scites nd mrked increse of eosinophils in the bdominl fluid. Most of our ptients presented with dirrhe, but we cnnot correlte symptoms with depth of eosinophilic infiltrtion, for ll our biopsies re endoscopic biopsies, nd submucos, musculris propri nd seros re generlly not smpled. Complementry tests cn be performed, but they hve limittions due to their lck of sensitivity nd specificity. First, llergic skin testing cn exclude n immunoglobulin E (IgE)-medited food llergy but positive test does not confirm the dignosis of EC [22]. Blood test my show nemi or low levels of lbumin. In some cses, there is n increse of levels of erythrocyte sedimenttion rte nd C-rective protein, which re signs of peripherl inflmmtion [23]. In respect of peripherl blood eosinophili (PBE), we hve found sttisticlly significnt differences between EC nd non-ec ptients. However, PBE ws only present in 27% of EC ptients nd 57% of ptients with PBE were not dignosed with EC. Thus, this finding cn be useful only in combintion with other clinicl nd pthologicl informtion. Endoscopic findings were suggestive of EC only in one ptient. Previous studies hve shown tht mny EC ptients hve no endoscopic ltertions, nd if present, they re usully not specific. The colonic mucos my show ptchy erythemtous chnges, loss of vsculr pttern or mild superficil ulcertion [22]. In this sense, we could regrd EC s one of the so-clled microscopic colitis, for ptients most frequently consult on dirrhe (66%) nd usully show no endoscopic bnormlities. Eosinophilic colitis: experience in lrge tertiry hospitl 787 A biopsy should therefore be performed for dignostic confirmtion of EC nd exclusion of other possible cuses. However, endoscopic biopsies re not useful to ssess the depth of eosinophilic infiltrtion, nd multiple biopsies should be obtined due to the ptchy distribution of the disese. Fetures commonly found in these biopsies re incresed mucosl eosinophils, ltered eosinophil distribution, extensive degrnultion, eosinophilic bscesses, intrepithelil eosinophils, rective epithelil chnges or lck of cute inflmmtion [24]. Regrding the number of mucosl eosinophils, the cut-off point for dignosing EC is not well settled. Most studies suggest cut-off point of 20 eosinophils/hpf. Our study shows tht this cut-off point does not precisely discriminte between EC nd other diseses leding to tissue eosinophili, for only 21.3% of the cses clssified s EC on histopthologicl grounds were cliniclly suggestive of this dignosis. Given tht eosinophils re normlly present in the bowel mucos in non-pthologicl conditions, this minimum number of eosinophils is probbly too low for the specific identifiction of EC cses. Some uthors hve suggested minimum of 60 eosinophils/hpf [25] nd Collins estblished different cut-off points for different lrge intestine res (>100 eosinophils/hpf in the right colon, >84 eosinophils/hpf in trnsverse nd descending colon nd >64 eosinophils/hpf in sigmoid colon nd rectum) [24]. In our study, we hve not been ble to perform this kind of nlysis to define seprte cut-off points, for most biopsies (specilly from norml endoscopies) re tken together from different res of the lrge intestine wll nd submitted in only one continer to the Deprtment of Pthology. Nevertheless, this lck of proper loction of the biopsies is common in everydy prctice, so we feel our study is rther representtive of rel clinicl sitution nd cn be useful for prcticing pthologist fced with this dignosis. We hve chosen cut-off point of 40 eosinophils/hpf for both men nd mximum number of eosinophils per HPF. With this cut-off point, we cn chieve sensitivity of 60% nd specificity of 50% for the dignosis of EC (ROC nlysis). Thus, the number of eosinophils per HPF should be considered in combintion with other microscopic fetures nd clinicl findings. Our results suggest tht the microscopic findings most closely relted to EC re the presence of rchitecturl distortion, intrepithelil eosinophils nd the bsence of cute inflmmtion. Clinicl findings, such s ge nd gender of ptients, presence of dirrhe or peripherl blood eosinophili cn lso support n EC dignosis. We recommend the elbortion of n EC protocol including the following items: men eosinophil count per HPF, mximum eosinophil count per HPF, loction nd distribution of eosinophils, signs of eosinophil ctivtion (eosinophilic bscesses, intrepithelil eosinophils nd extensive degrnultion), rchitecturl distortion, mucosl trophy, fibrosis, loss of epithelil mucin, presence of cute inflmmtion, lymphoplsmcytic infiltrtion nd lymphoid folliculr hyperplsi. Microscopic findings re seprtely reported, but they re not specific nd should be considered together. Mueller highlighted tht non-specific increse in eosinophils is commonly found

6 788 in lrge bowel biopsies, without ny obvious explntion [26]. The differentil dignosis should include ll possible cuses of intestinl eosinophili. Some histologicl findings cn be helpful, such s eosinophil distribution (eosinophilic infiltrtion is focl in collgenous nd lymphocytic colitis), the presence of cute inflmmtion (which is more frequently ssocited to inflmmtory bowel disese), the identifiction of prsite frgments in n edemtous bckground, or the presence of epithelil cell vcuoliztion nd poptosis (fetures seen in drug-induced EC). Some uthors suggest tht eosinophilic infiltrtion of the bowel wll is ssocited with IBD relpses. However, our results do not support this hypothesis [23]. A finl dignosis cn be rendered only fter clinicl correltion nd exclusion of ll other possibilities. In respect of EC tretment, no rndomized controlled trils hve been performed, nd ll vilble dt come from smll series of cses or cse reports. Clinicl mngement cn lso be extrpolted from other eosinophilic GI diseses. There re severl tretment options: corticosteroids, mst cell inhibitors or leukotriene receptor ntgonists, zthioprine or 6-mercptopurine, IL-5 inhibitors or dietry modifictions. Severl studies hve demonstrted n improvement in symptoms control with corticosteroids, but without histologicl correltion [27, 28]. The usul dosge is similr to tht of inflmmtory bowel disese, nd should be reduced grdully. Relpses re common nd mintennce therpy is usully necessry [29]. Mst cell inhibitors nd leukotriene receptor ntgonists hve lso demonstrted n improvement in symptoms control, nd they re frequently used in combintion with other drugs [30, 31]. Azthioprine nd 6-mercptopurine inhibit eosinophil growth fctors nd reduce the number of infiltrting eosinophils [32]. IL-5 inhibitors re still being studied nd some uthors suggest tht they could be used in refrctory or severe cses [7]. Allergic tests nd dietry modifictions hve been useful in eosinophilic proctocolitis in children, but in dults response to tretment is vrible [22]. There re three dietry options: n elementl diet, specific ntigen voidnce nd empiric food elimintion depending on the most common food ntigens [11]. In EE, some studies showed tht dietry tretment resolved 50 80% of cses [33]. However, Lucendo et l., in their systemtic review, concluded tht the unequivocl use of dietry tretment for ptients with primry eosinophilic GI disese cnnot be supported [13]. As for the course of the disese, EC in infnts nd children hs good prognosis, nd tends to resolve within severl dys. The food llergen cn lso be reintroduced in few yers [34]. However, in young dults EC is more frequently chronic disese with symptomtic periods followed by periods of remission [22]. Conclusions EC is rre nd not well-known disese. 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