Interfollicular Infiltrates of Follicular Lymphomas
CD10 expression in various grades and interfollicular infiltrates of follicular lymphoma (FL) has not been well documented. Immunohistochemical staining for CD10 (clone 56C6) was performed on paraffin-embedded tissue from 26 cases of classic FL. Negative or weak expression of CD10 was more frequent in grade III (5/6 [83%]) than in grade I FLs (3/15 [20%]). CD10+ interfollicular infiltrates were present in 16 cases. Six (38%) of 16 cases showed that CD10 expression was strong or moderate in follicular areas but weak or negative in interfollicular infiltrates. Our results suggest that CD10 expression is frequently weak to negative in grade III and in interfollicular infiltrates of FLs. Therefore, lack of CD10 expression on small specimens, such as from needle core biopsy or fine-needle aspiration, does not preclude the possibility of a diagnosis of FL. Furthermore, lack of CD10 expression in diffuse large B-cell lymphoma does not exclude the possibility that the neoplastic lymphocytes are of follicle center cell origin.
Follicular lymphoma (FL) is one of the most common types of lymphomas in adults. The Revised European-American classification and the World Health Organization classification of malignant lymphomas are based on further understanding of B-lymphocyte biology, careful morphologic evaluation, and application of immunophenotypic and genetic techniques. As such, FL has been defined by a follicular (nodular) pattern of lymphocytic infiltrate composed of neoplastic lymphocytes of follicle center cell origin, with and without diffuse areas. In addition to a B-cell phenotype (CD19+, CD20+), one of the immunophenotypic characteristics of FL is CD10 expression in the neoplastic cells.
CD10 is a 90- to 110-kd monomeric integral membrane glycoprotein that is expressed in a variety of neoplastic and nonneoplastic cell types. Its expression has been recognized as a characteristic marker for follicle center cells and FL, although other lymphoproliferative disorders, such as acute lymphoblastic lymphoma/leukemia and Burkitt lymphoma, may show CD10 expression.
Previous studies of CD10 expression in FL have been done by frozen section tissue and fresh tissue suspensions using frozen tissue immunohistochemical analysis and flow cytometric (FC) analysis, respectively. These methods do not permit detailed morphologic evaluation. Not surprisingly, the results of these studies show a wide variation (29% to 100%) of CD10 expression in FL. In addition, these studies do not provide information on the intensity of CD10 expression.
A monoclonal antibody to CD10 antigen (clone 56C6) has become available for detailed morphologic evaluation of CD10 expression in FL on paraffin sections. Preliminary studies have revealed that CD10 expression, as determined by this antibody, is a sensitive marker for FL. However, the spectrum of CD10 expression in various grades and in interfollicular infiltrates of FLs has not been well documented in those studies.
The main goal of the present study was to perform systematic morphologic evaluation of CD10 expression in various grades and in interfollicular infiltrates of FLs. The expression of CD10 by immunohistochemical analysis using paraffin sections was compared with that by FC analysis when FC analysis study results were available. We also evaluated bcl-2 expression by immunohistochemical analysis and correlated it with CD10 expression.
CD10 expression in various grades and interfollicular infiltrates of follicular lymphoma (FL) has not been well documented. Immunohistochemical staining for CD10 (clone 56C6) was performed on paraffin-embedded tissue from 26 cases of classic FL. Negative or weak expression of CD10 was more frequent in grade III (5/6 [83%]) than in grade I FLs (3/15 [20%]). CD10+ interfollicular infiltrates were present in 16 cases. Six (38%) of 16 cases showed that CD10 expression was strong or moderate in follicular areas but weak or negative in interfollicular infiltrates. Our results suggest that CD10 expression is frequently weak to negative in grade III and in interfollicular infiltrates of FLs. Therefore, lack of CD10 expression on small specimens, such as from needle core biopsy or fine-needle aspiration, does not preclude the possibility of a diagnosis of FL. Furthermore, lack of CD10 expression in diffuse large B-cell lymphoma does not exclude the possibility that the neoplastic lymphocytes are of follicle center cell origin.
Follicular lymphoma (FL) is one of the most common types of lymphomas in adults. The Revised European-American classification and the World Health Organization classification of malignant lymphomas are based on further understanding of B-lymphocyte biology, careful morphologic evaluation, and application of immunophenotypic and genetic techniques. As such, FL has been defined by a follicular (nodular) pattern of lymphocytic infiltrate composed of neoplastic lymphocytes of follicle center cell origin, with and without diffuse areas. In addition to a B-cell phenotype (CD19+, CD20+), one of the immunophenotypic characteristics of FL is CD10 expression in the neoplastic cells.
CD10 is a 90- to 110-kd monomeric integral membrane glycoprotein that is expressed in a variety of neoplastic and nonneoplastic cell types. Its expression has been recognized as a characteristic marker for follicle center cells and FL, although other lymphoproliferative disorders, such as acute lymphoblastic lymphoma/leukemia and Burkitt lymphoma, may show CD10 expression.
Previous studies of CD10 expression in FL have been done by frozen section tissue and fresh tissue suspensions using frozen tissue immunohistochemical analysis and flow cytometric (FC) analysis, respectively. These methods do not permit detailed morphologic evaluation. Not surprisingly, the results of these studies show a wide variation (29% to 100%) of CD10 expression in FL. In addition, these studies do not provide information on the intensity of CD10 expression.
A monoclonal antibody to CD10 antigen (clone 56C6) has become available for detailed morphologic evaluation of CD10 expression in FL on paraffin sections. Preliminary studies have revealed that CD10 expression, as determined by this antibody, is a sensitive marker for FL. However, the spectrum of CD10 expression in various grades and in interfollicular infiltrates of FLs has not been well documented in those studies.
The main goal of the present study was to perform systematic morphologic evaluation of CD10 expression in various grades and in interfollicular infiltrates of FLs. The expression of CD10 by immunohistochemical analysis using paraffin sections was compared with that by FC analysis when FC analysis study results were available. We also evaluated bcl-2 expression by immunohistochemical analysis and correlated it with CD10 expression.
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