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Case 41 - Discussion

Hematopathology Case

 

 

IMMUNOHISTOCHEMISTRY STAINS

   

CD3

CD5

CD20

CD79a

LCA

PAX5

CK AE1/3

CD23

Pancytokeratin cocktail

CK 8/18

CD34

Vimentin

 

 

The tumor cells show strong positivity for vimentin and focal positivity for CK 8/18, and focal weak positivity for CD45 and CD79a. They are negative for S100, synaptophysin, chromogranin, AE1/AE3 (pan CK), pancytokeratin cocktail, CD20, CD3, CD5, CD10, BCL6, CD23, PAX5, CD43, TdT, and CD34. Tumor cells are also negative for EBER-ISH and HHV8.

 

FLOW CYTOMETRY INTERPRETATION

INTERPRETATION:  An aberrant population of cells is detected, expressing dim CD45, CD138 and CD8 with surface kappa light chain restriction. The tumor cells are negative for CD3, CD4, CD5, and CD19.

 

 Total events           A Bright CD45 positive 
 analyzed = 49240 	events = 1167 (22% of total
  CD45+                          100%
  CD19+/CD5-           		  <2%
  CD5+/CD19-                      15%
  CD5+/CD19+                      <2%
  Total CD3+                      10%
  CD3+/CD4+          		   4%
  Total CD8+			  70%
  CD3+/CD8+        		   6%
  Total CD138+			  45%
  sIg Kappa+			  41%
  sIg Lambda+			  <2%
            	Gated on the CD19+ events
  CD19+/sIg Kappa+             CD19<2%
  CD19+/sIg Lambda             CD19<2%

 

MOLECULAR STUDY

Molecular tests for IGH Gene Rearrangement were performed on the specimen from GE junction.

The test result is reported as: Positive for Monoclonal IGH Rearrangement.

 

CASE INTERPRETATION AND DIAGNOSIS

  • Diagnosis: Plasmablastic Lymphoma

  • Clinical serologic studies showed no monoclonal immunoglobulin. The major differential diagnosis includes plasmacytoma and a poorly differentiated carcinoma. The patient had extensive involvement of lymph nodes, GI tract (GE junction and stomach) and bone marrow, however no monoclonal immunoglobulin was detected in the serum, which is unusual for a plasma cell neoplasm with systemic involvement. In addition, the tumor cells showed surface light-chain restriction, which is also not common for a plasma cell neoplasm. This case may resemble a poorly differentiated carcinoma due to its location at GE junction, cytology, expression of CK8/18, and lack of lymphoid markers. Overall, we favor a diagnosis of plasmablastic lymphoma. Plasmablastic lymphoma typically occurs in oral cavity of HIV patients, and 1/3 of cases may arise at other locations, including GI tract. Although majority of oral cases are positive for EBV, a substantial proportion of extra-oral cases have no association with EBV infection.