Differentiation and clonality of lesional lymphocytes in small plaque parapsoriasis

T-Cell Clonality in Pityriasis Lichenoides et Varioliformis Acuta

“…7 Still another explanation for our findings is that the dominant T-cell clone in PLEVA represents a clonal immunologic response to an unknown antigen or infectious agent. 2,9,[23][24][25] We favor the hypothesis that PLEVA is part of the clonal T-cell cutaneous lymphoproliferative spectrum, such as small plaques parapsoriasis, 26 as previously suggested. 6 The rare occurrence of lymphoma during the course of PLEVA and, in most cases, a spontaneous remission after several months, suggests that a vigorous host immune reaction controls and eventually eliminates the T-cell clone.…”

Atypical Large Plaque Parapsoriasis in a Young Adult

“…LPP, SPP, pityriasis lichenoides, and lymphomatoid papulosis, all have shown to be monoclonal disorders in many cases. [4] The classification and nomenclature of parapsoriasis is plagued with controversy. A historical reason of such controversies is the fact that the word 'plaque' in French means 'patch' without thickening or induration, but in English 'plaque' refers to a circumscribed thickened or indurated area, causing confusion.…”

Parakeratosis variegata: A Possible Role of Environmental Hazards?

“…The gene rearrangement detection technique may be very useful in monitoring the long-lasting cases of PV, in which there are no objective proofs of malignancy. However, this technique has also limitations, since monoclonal T-cell receptor γ-chain rearrangements were demonstrated in cases of parapsoriasis with histopathologically nonspecific T-cell infiltrates and no other signs of malignancy [8]. On the other hand, cases of PV with pronounced epidermotropic lymphocytic infiltrates and extensive cutaneous involvement showed no signs of monoclonal rearrangement and malignancy [19, 23].…”

“…In all variants of parapsoriasis, despite different clinical manifestations and course of the disease, the pathological process is virtually the same, with more or less pronounced epidermotropic lymphocytic infiltrates. The finding of monoclonality in some cases of small-plaque parapsoriasis [8], pityriasis lichenoides et varioliformis acuta (PLEVA) [9]and pityriasis lichenoides chronica [10]as well as the development of CTCL in long-lasting cases of PV strongly argue for a close link between all forms of parapsoriasis and their relationship with CTCL/mycosis fungoides [6, 11, 12, 13]. The natural history of PV and the frequency of development of overt malignancy are practically unknown.…”