Table 5.
Reactive conditions showing an abnormal* pattern of PD-1 expression
| N | Age (years) | PD-1 | Comment | |
|---|---|---|---|---|
| Atypical paracortical hyperplasia |
6 | 34.1 (13 – 73) |
83% (5/6) |
All cases showed a paracortical expansion with variable numbers of atypical cells, but minimal histologic suggestion of IM-like changes |
| Progressive transformation of germinal centers |
35 | 36.5 (11 – 69) |
100% (35/35) |
All cases show increased numbers of PD-1-positive cells in affected nodules, as well as increased numbers of extrafollicular PD-1- positive cells in between affected nodules |
| EBV Lymphadenitis |
10 | 16.4 (2 – 37) |
80% (8/10) |
Diffuse PD-1-positive cells within the paracortex is seen in all positive cases; 5 of 8 cases showed weak staining intensity |
| HIV lymphadenitis |
2 | 47.5 (38 – 57) |
100% (2/2) |
Paracortical hyperplasia with increased PD-1- positive; one case contained granulomas and one case also showed CMV infection |
| Rosai-Dorfman Disease | 3 | 44.6 (39 – 54) |
67% (2/3) |
Both positive cases showed diffuse PD-1-positive T-cells. PD-1 does not label characteristic histiocytes exhibiting emperipolesis |
Abbreviations: IM: infectious mononucleosis; EBV – Epstein Barr Virus; HIV – Human immunodeficiency virus; CMV – cytomegalovirus; N – number of cases studied.
*
An abnormal PD-1 staining pattern refers to the presence of PD-1-positive cells in extrafollicular (interfollicular) areas.