A combination of abnormal immunoarchitecture and reproducible clonal bands identifies the biologic nature of cutaneous B-cell infiltrates

In the multiparametric evaluation of cutaneous B-cell infiltrates (CBIs), immunoarchitectural features have been underused, and B-cell clonality alone has limited clinical usefulness. Our aim was to assess the usefulness of immunoarchitectural abnormalities (IAs) and clonality in the diagnosis-of CBIs. On 39 CBIS, immunohistochemistry was performed using anti- CD45, anti-CD45RO, anti-CD3, anti-CD20, anti-CD21, and anti-CD35, and polymerase chain reaction was used to detect immunoglobulin heavy chain rearrangement. There were 33 cutaneous lymphoid hyperplasias (CLHs) and 6 cutaneous B-cell lymphomas. IAs were present in 9 lesions and clonal bands in 14 lesions. In 6 cutaneous B-cell lymphomas, IAs were associated with pure and reproducible clonal bands. IAs in 3 CLH lesions with a superficial infiltrate were not associated with clonal bands. Clonal bands in 8 CLH lesions without IAs were not reproducible from deeper sections; furthermore, in 5 of 8 cases, these were present against a background smear. A combination of IAs and clonality is a useful adjunct in the diagnosis of CBIs.