CD21

CD21 is the C3d complement receptor. Antibodies are effective on paraffin-embedded tissue¹.

Immunohistochemical expression

• Follicular dendritic cells (FDC)

• B lymphocytes ( in cryostat sections only)

Diagnostic utility

Demonstration of the follicular dendritic cell meshwork of follicles in:

• HIV lymphadenopathy in which the follicles may be large and geographical, occupying much of the lymph node (progressive generalised lymphadenopathy stage I) or atrophic (PGL stage II)

  Follicle centre cell lymphomas.

• The nodules of nodular lymphocyte predominant Hodgkin's disease show a similar meshwork, but its outline is often more complex than that of the follicles of FCC lymphoma and may even be cerebreform.

• Residual germinal centres colonised by low-grade MALT lymphomas

• Interspersed FDC in mantle cell lymphoma / multiple lymphomatous polyposis of the colon

• T cell lymphoma of angioimmunoblastic type, in which the FDC meshwork is around hyperplastic venules.

• Castleman's disease (angiofollicular hyperplasia)

• FDC tumours

• Differentiation of Quilty lesions from acute cellular rejection after cardiac transplantation. Quilty lesions consist of an aggregate of CD20+ B-cells, with a rim of CD3+ T-cells. Most Quilty lesions, particularly those over 0.3 mm in size, have a network of CD21+ follicular dendritic cells. Foci of acute cellular rejection lack this structures and are usually devoid of CD21+ follicular dendritic cells².

References

¹ Leong A S-Y, Cooper K and Leong FJ W-M. Manual of diagnostic antibodies for immunohistology. 2nd edition, 2003

² Sattar HA, Husain AN, Kim AY, et al. The presence of a CD21+ follicular dendritic cell network distinguishes invasive Quilty lesions from cardiac acute cellular rejection. Am J Surg Pathol 2006; 30:1008-13

This page last revised 19.9.2006.

©SMUHT/PW Bishop