[Immunohistochemical patterns of follicular dendritic cell meshwork and Ki-67 in small B-cell lymphomas].
OBJECTIVE
To identify the immunohistochemical patterns of follicular dendritic cell (FDC) meshwork and Ki-67 labeling index in small B-cell lymphomas (SBLs) and their significance in differential diagnosis.


METHODS
Sixty-eight cases of SBLs were included collected from November 2008 to June 2012. The patterns of FDCs and Ki-67 expression were studied on paraffin sections by CD21, CD23 and Ki-67 immunohistochemistry. The characteristic staining patterns of FDCs and Ki-67 expression among different SBLs were analyzed statistically.


RESULTS
The age of SBL patients ranged from 28 to 85 years with a mean of 55.2 years. The male to female ratio was 1.2:1. Fifty-five cases involved only lymph nodes (80.9%), and the remaining cases involved multiple extra-nodal sites. Histological classification of the cases was made according to the 2008 WHO lymphoma classification criteria: 22 were low-grade follicular lymphomas (FLs, including grade 1 and grade 2), 19 marginal zone lymphomas (MZLs), 17 mantle cell lymphomas (MCLs), and 10 chronic lymphocytic leukemia/small lymphocytic lymphomas (CLL/SLLs). FDC meshwork limited to the central part of neoplastic follicles was characteristic for FL (90.9%, 20/22). The germinal center FDC meshwork was destroyed primarily at periphery in MZL (14/19). The absence or scattered FDC clusters were typical of SLL/ CLL. Irregular FDC was seen in 7/17 of MCL, while 7/17 MCL displayed FDC pattern similar to that of CLL/SLLs. The pattern of FDCs was a significantly diagnostic feature in distinguishing the four types of SBLs (P < 0.01). Ki-67 was also a statistically significant parameter (P < 0.05) with decreasing labeling index as the following: MCL, FL, SLL and MZL. Ki-67 showed scattered pattern in germinal centers with loss of polarity in FLs. MZL presented uniformly scattered positive pattern in interfollicullar areas. Ki-67 staining was uniform in MCL, but its labeling index varied from 5% to 90%. The Ki-67 index was higher in the morphological "proliferation centers" of all CLL/SLLs.


CONCLUSIONS
Immunohistochemical staining patterns of FDC meshworks and Ki-67 labeling index offer a significant discriminatory power in the differential diagnoses among SBLs.
Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education); Department of Pathology, Peking University Cancer Hospital & Institute, Beijing 100142, China.
Yun-fei
YF
Shi
Xiang-hong
XH
Li
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018951:Antigens, CD20 / Q000378:metabolism; D020566:Dendritic Cells, Follicular / Q000473:pathology*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D019394:Ki-67 Antigen / Q000378:metabolism*; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000378:metabolism / Q000473:pathology; D016393:Lymphoma, B-Cell / Q000145:classification / Q000378:metabolism* / Q000473:pathology*; D018442:Lymphoma, B-Cell, Marginal Zone / Q000378:metabolism / Q000473:pathology; D008224:Lymphoma, Follicular / Q000378:metabolism / Q000473:pathology; D020522:Lymphoma, Mantle-Cell / Q000378:metabolism / Q000473:pathology; D008228:Lymphoma, Non-Hodgkin / Q000378:metabolism / Q000473:pathology; D008297:Male; D008875:Middle Aged; D017464:Receptors, Complement 3d / Q000378:metabolism; D017455:Receptors, IgE / Q000378:metabolism; D012189:Retrospective Studies
D018951:Antigens, CD20; D019394:Ki-67 Antigen; D017464:Receptors, Complement 3d; D017455:Receptors, IgE