Angioimmunoblastic T-Cell Lymphoma

Lessons From the Friday Unknowns

Histologic sections show a moderately enlarged lymph node with an atypical proliferation of small lymphoid cells with pale cytoplasm, eosinophils, histiocytes, and increased high endothelial venules. Small foci of dermatopathic change are also present.

Most of the lymphoid cells are T-cells, positive for CD2, CD3, CD4, CD5 and CD7 (dim), and negative for CD8. The atypical T-cells appear to be positive for ICOS, but are negative for BCL-6, CXCL-13 and PD-1. The antibody specific for CD20 highlights residual lymphoid follicles and scattered B cells throughout the atypical infiltrate. The antibody specific for CD21 highlights follicular…