Retroperitoneal Sclerosing Perivascular Epithelioid Cell ... · reports of the sclerosing type of tumours. Literature review, using PubMed, of intraperitoneal / retroperitoneal type
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Hong Kong J Radiol. 2015;18:51-6 | DOI: 10.12809/hkjr1414242
CASE REPORT
Correspondence: Dr Victoria YK To, Department of Radiology. Tuen Mun Hospital, Tuen Mun, New Territories, Hong Kong.Tel: (852) 2468 5175, (852) 2468 5177; Email: [email protected]
Department of Radiology, Tuen Mun Hospital, Tuen Mun, Hong Kong
ABSTRACTPerivascular epithelioid cell tumour is a relatively new entity with rising incidence. This is a rare mesenchymal neoplasm that can occur in various organs and is characterised by proliferation of perivascular cells and expression of myomelanocytic markers. Here, we present an asymptomatic 52-year-old female patient with an incidental radiological finding of a large retroperitoneal mass, histologically and immunohistochemically proven to be a sclerosing type of perivascular epithelioid cell tumour. The mass showed typical morphological and microscopic features consistent with those described in the current literature. However, it had computed tomography findings of neovascularisation and hyper-vascularity, not often documented in previous case reports of the sclerosing type of tumours. Literature review, using PubMed, of intraperitoneal / retroperitoneal type of tumours, and specifically the sclerosing type, was performed. To the best of our knowledge, less than 20 sclerosing perivascular epithelioid cell tumours have been reported and few describe the associated radiological features.
The PEComa family includes angiomyolipoma(AML), clear-cell sugar tumour (CCST), lymphangio-myomatosis (LAM), clear-cellmyomelanocytictumour (CCMMT)of the falciform ligament andnon-specific typesoccurring in thepelviccavity,abdominal cavity,digestive tract,genitourinary tract,and the surrounding soft tissuesor skin.3They showa femalepredilectionandaffectmiddle-agedadultsmost commonly.ConventionalPEComasusuallyarise from theabdominopelvicanduterine regions. Incontrast, thesclerosingsubtype,whichischaracterisedbyextensivehyalinised stroma, ispredominantlyfound in the retroperitoneum.4Someauthors suggestthatmacroscopic fat andhypervascularitymightbethe radiological featuresof theconventionalPEComafamily,5,6especiallywhenconsideringAMLasthemostcommonPEComa.To thebestofourknowledge, todate,therearelessthan20casesofsclerosingPEComasreported in theEnglish literatureand fewof themincluderadiologicalfindings.4,7,8Herein,wepresentthedetailed radiological featuresof ahistopathologicallyproven sclerosingPEComaanda literature reviewfocusingon the radiological featuresof sclerosingPEComaandintraperitoneal/retroperitonealPEComa.
CASE REPORTWepresent thecaseof a52-year-oldwomanwhowas followedupbyDepartmentofMedicineatTuenMunHospital,HongKong, forhypertension.Shewas
asymptomatic all along.Physical examinationwasunremarkable.Bloodresultsshowedrenal impairment.Thus,ultrasoundofthekidneyswasperformed.
Ultrasound revealeda large,well-definedechogenicmass in the right lowerabdomencloselyabutting thekidneyand liver. Internalvascularitywasnoted.Nointernalfatorcalcificationwasidentified(Figure1).
Further investigationwithcomputed tomography (CT)was subsequentlyperformed.Therewasa large (8.5cm) retroperitonealmasscloselyabutting theposterioraspect anddisplacing the rightkidney (Figure2).Therewasno internalhypodense focus suggestiveofmacroscopic fat componentonprecontrast scan.Itdemonstratedheterogeneousenhancementuponcontrast administration.Multiple tortuousbranchesfrom theaorta supplied the lesion.Neitherkidneyshowedany focal solidmass.Therewerenoenlargedintra-abdominal lymphnodes.Lungbaseswereclear.Noosseousdestructionwasseen.
Thepatientwas referred to theurology teamandelectiveexcisionof the retroperitonealmasswasperformed uneventfully. The right kidneywassuccessfullypreserved.
Morphologically, the tumourwas solidwithgreyish-yellowsurfaceand tinycysticchanges.Histologically,low-power examination showed that the tumourcell clusterswerearranged inamarkedlyhyalinised
Figure 1. Ultrasound images show (a) a large well-defined echogenic mass in right lower abdomen closely abutting the kidney (arrow). No internal fat or calcification was identified; (b) internal vascularity was noted (arrow).
DISCUSSIONPEComa is a relatively rareandnewlydiscoveredgroupofmesenchymalneoplasms sharingdistinctmorphological,histological, and immunohistochemical
(a) (b)
Figure 2. Computed tomography of the abdomen with contrast. (a) A large heterogeneous, enhancing retroperitoneal mass (arrow) is found closely abutting the posterior aspect and displacing the right kidney. (b) The lesion (arrow) was supplied by multiple tortuous branches from the aorta. Neither kidney shows any focal solid mass. There are no enlarged intra-abdominal lymph nodes.
Figure 3. Low-power examination of a photomicrograph of the tumour. Tumour cell clusters (arrows) are arranged in an extensive sclerotic stroma (H&E; original magnification, x 4).
Figure 4. High-power examination of a photomicrograph of the tumour. Tumour cells are spindle-shaped (arrows) with moderate amount of lightly eosinophilic or vacuolated cytoplasm (H&E; original magnification, x 200).
features.2ThePEComasarecharacterisedbyepithelioidcellsandacloserelationshipwithbloodvessels.Theyareconsistently immunoreactive for themelanocyticmarkerHMB45,andarevariably immunoreactive tosmoothmuscleactin.Theyarenegative for epithelialmarkers.9
ThePEComa family includesAML,CCST,LAM,CCMMT,andnon-specifictypesoccurringinthepelvic
Thereis,asyet,noconsensusonthediagnosticcriteriafor thebenignormalignant type, as its clinical andradiologicalbehaviour is still notwelldocumented.Oneof the currently accepted classifications formalignantPEComaswasproposedbyFolpe in2002.1 Theyproposedthatatumoursizegreaterthan5cm,aninfiltrativegrowthpattern,highnucleargrade,necrosis,mitotic activity of>1/50high-power fields, andaggressiveclinicalbehavioursuggestamoremalignantpathology. Inourcase, thesizewasgreater than5cmandhadhighmitoticactivitybutdidnothavefeaturesofinvasionorsignificantclinicalsymptoms.Thus,ourcasehadmixedcharacteristics,typicallydemonstratingthedifficulty inpredicting thebiological courseandprognosisofthistumour.
Theimagingfeaturesofintraperitoneal/retroperitonealPEComa family other thanAMLamongEnglishradiology literature are relatively scarce.Mostintraperitoneal / retroperitonealPEComas reported inthepreviousliteraturearewell-circumscribedenhancingmass lesions.A fewof these lesionswere shown tobehypervascular,pathologicallyor radiologically.Someauthors suggested thatmacroscopic fat andhypervascularitymightbe the radiological featuresoftheconventionalPEComa family,5,6 especiallywhenconsideringAMLasthemostcommonPEComa.Afewof therecentcasereports, includingours,donotshow
macroscopicfatonCT(Table16,7,10-12).
To thebestofourknowledge, todate, thereare lessthan20 reportedcasesof sclerosingPEComa in theEnglishliteratureandfewofthemincluderadiologicalfindings.4,7,8Noneofthereportsmentionedmacroscopicfatorhypervascularityas a significant feature in thesclerosingtypeofthetumour(Table24,7,8,13).
ConsistentwithpreviouscasereportsonretroperitonealPEComa,ourpatientwas typicallyasymptomatic,despite the large tumour size.Thiscouldbe related tothewell-circumscribednatureofthemasswithlackofinvasionoftheadjacentorgans.
Radiologically,our case showedneovascularisationbymultiple tortuousbranches from theaorta.Perhapsin futurepractice, thisnew rareentityof sclerosingPEComamayalsobeconsidered in thedifferentialdiagnosisofhypervascular retroperitonealmassesinaddition tohemangiopericytomas, sarcomas,orlymphoma.However,differentiationbetween thesedifferentialscanbedifficultastheyalltypicallypresentas large,well-encapsulated, retroperitonealmasses.Sinceonlyaround20casesofsclerosingPEComahavebeen reported, it remainschallenging to identify thetypicalimagingfeaturesofthisdisease.
with thevesselwall andextensivehyalinised stroma,which is characteristic of the sclerosing type ofPEComa.4Ourcase,agreeingwithcasesinthepreviousliterature, also showed immunoreactivity toHMB45,whichisoneoftheuniquefeaturesofthisdisease.2-4,9,14
Surgery is currently themainstayof treatment, aschemotherapy and radiotherapyhave not shownsignificant results.ThemajorityofPEComas reportedin literaturearebenignwithgoodprognosis.3,9,15Ourpatient remaineddisease-free for at least2years, alsosuggestingabenigncourse.
In conclusion,wepresent a rare caseof a histo-pathologicallyproven, retroperitoneal, sclerosingPEComa,with radiological findingsofneovasculari-sationandhypervascularity,whicharelessemphasisedinpreviouscasereports.Tothebestofourknowledge,less than20casesof sclerosingPEComahavebeenreported in theEnglish literature todate, and fewofthem include radiological findings.The radiologicalfindingsofneovascularisationandhypervascularitypropose thepossibilityof adding sclerosingPEComato the listofhypervascular retroperitonealmasses.Moreover, therewasnomacroscopic fat identifiedonCT inourcase,which someauthorsbelieve tobea characteristic imaging feature in theconventionalPEComa family.Due to the rarityof thedisease, thedistinctimagingfindingsareyettobeestablished.
4. HornickJL,FletcherCD.SclerosingPEComa:clinicopathologicanalysisofadistinctivevariantwithapredilection for theretroperitoneum.AmJSurgPathol.2008;32:493-501.cross ref