All posts by peferguson

Organ Systems, Lymph Node, WHO Classification

T-Cell/Histiocyte-Rich Large B-Cell Lymphoma

T-Cell/Histiocyte-Rich Large B-Cell Lymphoma (TCHRLBCL) is characterized by spleen and bone marrow involvement.  The morphology is of scattered large B-cells with a predominant background composed of T-cell and Histiocytes.  The immunophenotype is variable, and an important differential diagnosis is with Hodgkin lymphoma.

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Organ Systems, Lymph Node, WHO Classification

Primary Cutaneous DLBCL, Leg Type

Primary Cutaneous DLBCL, Leg Type is an uncommon cutaneous lymphoma (<5% of cutaneous lymphomas), but and important entity to differentiate due to its aggressive course.  Unlike other cutaneous B-cell lymphomas, which are generally indolent and treated locally, primary cutaneous DLBCL, leg type behaves in a similar fashion to the systemic DLBCL (intermediate grade lymphoma) and is treated as such.

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Organ Systems, Bone Marrow, Lymph Node, WHO Classification

Intravascular Large B-Cell Lymphoma

The B-cell population is predominately confined to the lumen of blood vessels.  The IHC immunophenotype may be similar to other DLBCLs and may have either a germinal center or non-germinal center immunophenotype.  There are several important characteristics.
Immunophenotypic Expression Characteristics
Marker
Comment
Negative (pan T-cell marker)
Positive
Co-expression may be seen on ~38% of the lymphoma cells.
Co-expression may be seen on ~13% of the lymphoma cells.
Variable.  Usually positive in CD10 negative cases.
References
Parker, A., et. al.  “Best Practice in Lymphoma Diagnosis and Reporting.”  British Committee for Standards in Haematology, Royal College of Pathologists.  April, 2010.
 
Hematopathology. [edited by] Jaffe, ES. 1st. ed. Elsevier, Inc. © 2011.
Organ Systems, Bone Marrow, Lymph Node, WHO Classification

Primary Effusion Lymphoma (PEL)

Primary Effusion Lymphoma (PEL) is a rare form of DLBCL associated with HIV infection.
Immunophenotypic Expression Pattern
Marker
Comment
Negative
Variable (often negative)
Positive
Positive
Positive
EBV (EBER)
Positive (majority of cases)
HHV-8
Positive
References
Parker, A., et. al.  “Best Practice in Lymphoma Diagnosis and Reporting.”  British Committee for Standards in Haematology, Royal College of Pathologists.  April, 2010.
Organ Systems, Bone Marrow, Lymph Node, WHO Classification

Chronic Lymphoproliferative Disorders of NK Cells

This is considered a provisional entity by the WHO classification in 2008.   In many ways this entity is similar clinically to T-LGL leukemia, but there are no rearrangements of immunoglobulin or T-cell receptors since the cells are NK cells.
Characteristic Immunophenotypic Profile
Marker
Comment
Surface CD3 negative.  Cytoplasmic CD3ε is often positive.
Usually weak expression
TIA-1
Positive
Positive
+/- May show diminished of loss of expression.
+/- May show diminished of loss of expression.
CD57
+/- May show diminished of loss of expression.
May show aberrant uniform expression.
References
Hematopathology. [edited by] Jaffe, ES. 1st. ed. Elsevier, Inc. © 2011.
Organ Systems, Lymph Node, WHO Classification

Anaplastic Large Cell Lymphoma, ALK-

Immunophenotypic Expression Pattern
Marker
Comment
Negative, by definition.
Positive, should be strong and of equal intensity.
+/- more often positive than CD5
+/- more often positive than CD5
Usually Positive
-/+
+/-
Negative (rare +)
Negative
Often Positive
EBV (EBER)
Negative.  If positive, it should raise concern of a classical Hodgkin lymphoma.
Often Positive
Perforin
Often Positive
TIA-1
Often Positive
Negative
Negative.  If positive, then this should raise the possibility of classical Hodgkin lymphoma.
References
Parker, A., et. al.  “Best Practice in Lymphoma Diagnosis and Reporting.”  British Committee for Standards in Haematology, Royal College of Pathologists.  April, 2010.
 
Hematopathology. [edited by] Jaffe, ES. 1st. ed. Elsevier, Inc. © 2011.  pp. 312-19.
Organ Systems, Lymph Node, WHO Classification

Anaplastic Large Cell Lymphoma, ALK+

Immunophenotypic Expression Pattern
Marker
Comment
Variably Positive (up to a 1/3rd may be Negative)
Positive in >50% of cases.
Positive by definition.  Nuclear and cytoplasmic expression is c/w t(2;5).  ALK may show nuclear, membraneous, or cytoplasmic localization dependent upon what type of translocation is involved.
Positive
Positive (70%)
Negative in >75% of cases (rare +)
Positive (70%)
Negative (rare +)
+/- (70%)
Negative (rare +)
Negative
Positive (majority)
EBV (EBER)
Negative
Perforin
Usually Positive
Usually Positive
TIA-1
Positive
Negative
Negative
References
Parker, A., et. al.  “Best Practice in Lymphoma Diagnosis and Reporting.”  British Committee for Standards in Haematology, Royal College of Pathologists.  April, 2010.
 
Hematopathology. [edited by] Jaffe, ES. 1st. ed. Elsevier, Inc. © 2011.  pp. 312-19.