The case is Courtesy of dr.R.Meškauskas. Unfortunatelly we have not CD123 for final confirmation (flow only). The case is the first one there.  
 
86 yrs old female with clinical diagnosis "B cell lymphoma" was biopsied (skin nodule from back).  
HISTORY: The nodule in the back was noticed in 2009 July. The non-itching eruption progressed and covered back skin, thorax and shoulders.  
CLINICALLY: 2-7 cm bluish nodules in the back skin.  
Additional threpine biopsy was taken.  
FLOW CYTOMETRY: CD123+, CD45+dim, CD33+dim, CD56+, CD4+dim, CD43+, HLA-DR+, CD13-, CD34-, CD117-, cMPO-, cCD3-, cCD79a- (interpretation: blastic tumor, most probable blastoid dendritic cell tumor).  
During IH stainning ADDITIONAL skin biopsy was taken from femoral skin with clinical diagnosis "dysplastic nevus".  
 
HISTO:  
SKIN 1 (back): blastoid "leukaemic" infiltrate with IH: LCA+; CD4+; Bcl2+; CD20/Cd79a/Pax5/CD3/CD5/CD2(-), CD30/CD10/CD5/CD23/CD21(-), Bcl6/CyclinD1/Ig Kappa/Ig Lambda(-), CD68/MPO/CD34/Tdt/CD56/S100/Cd56/Cd117(-).  
SKIN 2 MELANO (femur): 1) Identical "blastoid" infiltrate: LCA+, CD4+, Bcl2+ (Ki67+ 40%): 2) MelanA+ pagetoid spread of Melanoma in situ within mixt dysplastic nevus.  
BM: erythroid hyperplasia, architectural distortion with interstitial infiltrate of NASDE(-) "blastoid cells" 10% with immunophenotype: Bcl2+; CD34/CD117/TdT(-), CD4(-)(? technical reasons?).  
 
DIAGNOSIS: 1. Blastoid dendritic cell ("hematodermic") tumor: multifocal spread in skin (back, femur) and bone marrow. 2. Melanoma in situ (femoral skin) in mixt dysplastic nevus.  
QUEST: Interstitial vs nodular infiltrates in DC2 tumors in the skin.  
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