Table 1 Pathologic Features of EBVMCU

Shallow, sharply circumscribed ulcers

Immunoblasts often with HRS features:

 strong positivity for CD10, CD30, MUM1

 uniform positivity for PAX5 and OCT-2

 variable expression of CD20, CD45, CD15, CD79a, BCL-6, BOB.1

Localized to mucosa of oropharynx and gastrointestinal tract or to skin

Infiltrating lymphocytes:

 CD4 and CD8 positivity

Polymorphous infiltrate of lymphocytes and immunoblasts

Clonality

Variable admixture of scattered plasma cells, eosinophils, and histiocytes

Immunoblasts with HRS features:

 monoclonal immunoglobulin rearrangement

Medium sized lymphocytes with angulated nuclei

Infiltrating T-lymphocytes:

 frequent monoclonal or restricted TCR pattern

Pleomorphic immunoblasts with frequent Hodgkin and Reed-Sternberg (HRS) morphology

Association with EBV

Plasmacytoid apoptotic cells

Immunoblasts and HRS cells:

 uniformly EBER1-positive

Variable angioinvasion

Infiltrating T-lymphocytes:

 frequently EBER1-positive

Variable tissue necrosis

Plasmacytoid apoptotic cells:

 uniformly EBER1-postive