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Catherine M. Stefanato, MD, FRCPath Consultant in Dermatopathology
St John’s Institute of Dermatology London, UK
NEGATIVEIMMUNOSTAINS
• MNF116:nega8ve• Cytokera8n7:nega8ve• Cytokera8n20:nega8ve• S100:nega8ve• Mel5:nega8ve
Mel5
POSITIVEIMMUNOSTAINS
• MelanA(cytoplasmic):posi8ve• MiTF1(nuclear): posi8ve• SOX10(nuclear): posi8ve
Pseudomelanocy8cnests:Whatarethey?
• Aggregatesofcellsandcellfragmentsthatincludekera8nocytes,macrophages,lymphocytes
• Transferofmelanosomesormelanocy8cepitopestonon-melanocy8ccellsasconsequenceoflichenoid8ssuereac8on
• IntheseUngoflichenoidinflamma8onpseudomelanocy8cnestsmaymimicanatypicalmelanocy8cprolifera8on
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AE1/AE3 MelanA
MiTF SOX10
Dx:Lichenplanuspigmentosus/erythemadyschromicumperstans
CLINICOPATHOLOGICALCORRELATION Pseudomelanocy8cnests:Howtoavoidthepi^all?
• MelanAcanbedetectedinthecytoplasmofnon-melanocy8ccells(melanocy8cdebrisengulfedbymacrophagesintheseUngoflichenoidinflamma8on)
• MiTFandSOX10arenuclearstainsBUTnottotallymelanocy8cspecific(SOX10:Schwanncellsandmyoepithelialcells.MiTFmacrophagesandmastcells)
• S100nega8vity:mostspecificmarkerbutcomplexinterpreta8onduetoLangerhanscellsandmacrophages
Direct Immunofluorescence
• IgM:granulardeposi1onalongtheBMZ&• colloidbodies• IgG:lineardeposi1onalongtheBMZ• IgA:colloidbodies• Fibrinogen:Lineardeposi1onalongtheBMZ• ThioflavinT:nega1ve
A. Len8gomalignaB. LichenplanuspigmentosusC. Melano8clupusD. Pigmentedac8nickeratosis
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ACQUIREDFACIALMELANOSES• Melasma• Lichenplanuspigmentosus
• Melano1c(Discoidlupuserythematosus
• Drug-inducedmelanosis
• Argyria• Macularamyloidosis• Fixeddrugerup1on
• Ochronosis• Acanthosisnigricans• PoikilodermaofCivaQe
• Riehl’smelanosis(pigmentedcontactderma11s)
• Hori’snevus(acquiredbilateralnevusofOtalikemacules)
Melano1cLupuserythematosus
• PigmentedmacularsubsetofDLE• MorecommoninIndian/Asianpopula8on• Hyperpigmenta8onarising‘denovo’withouterythema,indura8onorscaling
• Confusedwithlichenplanuspigmentosus• Immunofluorescencestudiesessen8alinthediagnosis
PatelAB,RKubba,AKubba:Clinicopathologicalcorrela8onofacquiredhyperpigmentarydisorders.IndianJDermatolVenereolLeprol2013;79:367
• DrGianlucaPetrillo• DrGerardoFerrara