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

References

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

©SMUHT/PW Bishop