Expression of cutaneous lymphocyte-associated antigen and TIA-1 by lymphocytes in pityriasis lichenoides et varioliformis acuta and lymphomatoid papulosis: immunohistochemical study.

BACKGROUND

Pityriasis lichenoides et varioliformis acuta (PLEVA) and lymphomatoid papulosis (LyP) are benign self-healing cutaneous eruptions that may be clinically and histologically similar. The purposes of this study were to evaluate immunohistological characteristics of PLEVA and LyP and to investigate whether Epstein-Barr virus (EBV) may be present in PLEVA and LyP.

METHODS

We performed an immunohistochemical staining in 12 cases of PLEVA and 8 cases of LyP using nine antibodies for CD3, CD4, CD8, CD30, CD45RO, CD56, CD79, cutaneous lymphocyte-associated antigen (CLA), and TIA-1. In situ hybridization was performed using fluorescein-conjugated oligonucleotide probes for EBV early regions (EBER).

RESULTS

In PLEVA, immunohistochemical studies revealed that infiltrated lymphocytes consisted of mainly CD3-positive (5+), CD8-positive (4+ to 5+), CLA-positive (4+ to 5+) T cells and partly CD79 positive (+ to 2+) B cells. CD4-positive T cells were less than 25%. In LyP, immunohistochemical studies revealed that infiltrated lymphocytes consisted of partly CD3-positive (5+), CD8-positive (2+ to 3+), CLA-positive (3+ to 4+) T cells and partly CD79-positive (2+ to 3+) B cells. CD4-positive T cells were less than 10%. CD8 and CLA were more strongly expressed in PLEVA than in LyP. CD30 was strongly expressed in LyP but not expressed in PLEVA. CD79 was more expressed in LyP than in PLEVA. TIA-1 was not expressed in any cases. In situ hybridization using antisense EBER probe showed negative reaction in all cases.

CONCLUSIONS

Immunohistochemical stains for CD8, CD30, CD79 and CLA may be valuable tools in the differential diagnosis between PLEVA and LyP. TIA-1 was negative in LyP, which means cytotoxic cells may not be implicated in the pathogenesis of LyP. It was a contradictory result to the previous results. The absence of EBV in PLEVA and LyP suggests that this virus may not be operative in the pathogenesis of these diseases. These results suggest that LyP and PLEVA are separate disorders, thus accounting for their variable prognosis.