Context : Aims : Wepresentspatiallyresolvedmid-infraredimagesofthedisksurroundingtheyoungstar IRS~48 intheOphiuchuscloudcomplex.Thediskexhibitsaring-likestructureat18.7 \mu m , andisdominatedbyverystrongemissionfrompolycyclicaromatichydrocarbonsatshorterwavelengths.Thisallowsadetailedstudyoftherelativedistributionsofsmallandlargedustgrains . Methods : Imagesof IRS48 in5mid-infraredbandsfrom8.6to18.7 \mu maswellasalowresolutionN-bandspectrumareobtainedwithVLT-VISIR.OpticalspectroscopyisusedtodeterminethespectraltypeofthecentralstarandtomeasurethestrengthoftheH \alpha line . Results : The18.7 \mu mringpeaksatadiameterof110 AU , withagapof \sim 60 AU.Theshapeoftheringisconsistentwithaninclinationof i = 48 \degr \pm 8 \degr .Incontrast , the7.5-13 \mu mPAHemissionbandsarecenteredonthesourceandappeartofillthegapwithinthering.ThemeasuredPAHlinestrengthsare10–100xstrongerthanthosetypicallymeasuredforyoungM0starsandcanonlybeexplainedwithahighPAHabundanceand/orstrongexcessoptical/UVemission.Themorphologyoftheimages , combinedwiththeabsenceofasilicateemissionfeature , implythattheinnerdiskhasbeenclearedofmicron-sizeddustbutwithasignificantpopulationofPAHsremaining.Wearguethatthegapcanbeduetograingrowthandsettlingortoclearingbyanunseenplanetaryorlow-masscompanion.IRS48mayrepresentashort-livedtransitionalphasefromaclassicaltoaweak-lineTTauristar . Conclusions :