Large plaque parapsoriasis: clinical and genotypic correlations

Abstract

Twelve patients with large plaque parapsoriasis (LPP) were investigated for the presence of predominant T-cell clones, analyzing the T-cell receptor (TCR) gamma-chain gene. The diagnostic and prognostic significance of TCR gene rearrangement status was assessed by a correlation with the long-term clinical follow-up. Six out of 12 patients showed a clonal T-cell population. Clinically, among the patients with clonal disease one developed clearcut mycosis fungoides (MF) after a follow-up of 8 years, in the other 5 patients no such diagnosis could be made after follow-up of 2-21 years (median: 9 years). In patients with polyclonal infiltrates the lesions remained virtually unchanged. These findings indicate that in LPP TCR gene rearrangement status has no prognostic significance and does not allow distinction of LPP and early MF. Both conditions show a clonal T-cell infiltrate with similar frequency, are very similar in clinical and histologic presentation and according to recent studies share the same low risk to develop overt MF. Therefore both terms refer to the identical clinical situation. This should be designated as early MF and efforts should concentrate on identifying those patients that are at risk to develop aggressive disease.

Practical Aspects Regarding the Histopathological Diagnosis of Early Mycosis Fungoides

“…But parapsoriasis is defined by some authors as a reactive inflammatory disease different from mycosis fungoides, whereas others understand parapsoriasis as an initial phase of mycosis fungoides. Transition between the histological picture of both diseases has been clearly described in the literature [30][31][32][33]. This is in accordance with the theory which suggests an existence of a biologic grey zone between nonneoplastic inflammatory dermatoses and MF [34].…”

Defining early mycosis fungoides

“…DNA cytophotometry, 33-37 nuclear morphometry, 38-41 immunohistochemistry, 42-57 chromosomal studies, [58][59][60] and, more recently, molecular genetic analysis of T-cell clonality 8,[55][56][57][61][62][63][64][65][66][67][68][69][70][71][72][73][74][75][76][77][78] have generated a significant amount of data that suggest their utility not only in the early diagnosis of MF but also potentially in the clinical management of MF patients. How these data may be integrated with light microscopy to aid in the definitive diagnosis of CTCL has not been standardized.…”

Human Herpesvirus 8 Infection in Patients With Cutaneous Lymphoproliferative Diseases

“…A 9-year follow-up study did not confirm that parapsoriasis leads to MF, even in the presence of occasional T-cell clonality. 45 With regard to our patients with LPP, in 2 cases we detected blood and tissue T-cell-prevalent clones, with different TCR rearrangements of V␥ 9 or V␥ l-8 , highlighting the existence of an immune stimulation.…”