Pityriasis lichenoides: A clonal T-cell lymphoproliferative disorder

Pityriasis lichenoides chronica: stratification by molecular and phenotypic profile

“…Second, lymphoid atypia including cells with a cerebriform appearance, is frequent. Lymphoid atypia was demonstrated with regularity in this series and has been described in other articles [9,11,12,19]. The extent of lymphoid atypia could be correlated with the molecular findings.…”

“…There was a dominance of CD8 lymphocytes in more than 50% of cases. It has been previously hypothesized that the CD8 lymphocytes are reactive and may define the counterregulatory cell population directed against an aberrant clonally restricted CD4 population [9,25]. The Foxp3 cells are pathogenetically unrelated to CD8 but may play an important role in controlling disease progression.…”

“…Despite earlier convictions that PL is a benign inflammatory dermatosis, a position still held by many practicing dermatologists, an emerging body of literature suggests that PL may represent a form of cutaneous T-cell lymphoid dyscrasia (CTLD) [6][7][8][9][10][11][12][13][14]. To further define and validate the claim of PL as a form of CTLD, we stratified all prospectively encountered cases of PL in our practices according to their phenotypic and molecular profile.…”

Polymerase chain reaction-based clonality testing in tissue samples with reactive lymphoproliferations: usefulness and pitfalls. A report of the BIOMED-2 Concerted Action BMH4-CT98-3936

“…In biological terms, histologically reactive lesions represent a broad spectrum of lesions ranging from heterogeneous, polyclonal lymphocytes, via true reactive lymphoproliferations, to proliferations containing (oligo)clonally activated lymphoid cell populations or even a monoclonal component. [5][6][7][8][9][10][11] Reactive lymphoproliferations in lymph nodes or other tissues arising upon infection with micro-organisms (e.g. Epstein-Barr virus (EBV), cytomegalovirus, human immunodeficiency virus infections, toxoplasmosis, tuberculosis, cat scratch disease) or being associated with particular inflammatory processes (e.g.…”

PUVA-Therapie einer schwer verlaufenden Pityriasis lichenoides et varioliformis acuta

“…Es wird eine medikamenten-oder infektallergische Reaktion vermutet, die zu einer oberflächlich-nekrotisierenden Vaskulitis führen kann [5,10]. Sowohl die PLEVA als auch die PLC wurden daher frü-her als benigne Erkrankungen angesehen, die spontan,bei der PLEVA oft unter varioliformer Narbenbildung, abheilen, aber auch mehrfach rezidivieren können.In den letzten Jahren wurde mehrfach eine Assoziation mit kutanen T-Zell-Lymphomen diskutiert [3,6,8,11].Weinberg et alkonnten bei 57% aller untersuchten Patienten mit PLEVA ein monoklonales Rearrangement des T-Zell-Rezeptors, wie dies für kutane T-Zell-Lymphome typisch ist, finden; bei der PLC war dies lediglich bei 8% der Patienten der Fall [11]. Fortson et al beschrieben 2 Kinder, bei denen wenige Jahre nach einer PLEVA eine Parapsoriasis en plaques histologisch gesichert werden konnte [3].…”