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[Ultrastructure of parapsoriasis lesions. Parapsoriasis en plaques and parakeratosis variegata as prelymphoma; differences from pityriasis lichenoides].

The morphological alterations of involved skin in three different types of parapsoriasis were investigated in 9 patients by electron microscopy. Pityriasis lichenoides chronica (PLC) is characterized by a lymphohistiocytic dermal infiltrate and by epidermotropic histiocytic cells, which penetrate up to the horny layer. In parapsoriasis en plaques (PeP) and in parakeratosis variegata (PV) the dermal infiltrate is mainly composed of lymphocytoid cells, some of which, particularly in PV, reveal the features of Sézary-Cells (11% and 30% respectively). The epidermis is predominantly invaded by partly atypical lymphoid cells. In some instances membrane contacts between Langerhans cells, keratinocytes and atypical lymphoid cells can be observed. The increased number of epidermotropic cells and the increase of atypical lymphoid cells in the dermal infiltrate are the main ultrastructural features of the malignant transformation of PV. Finally, an important difference between PLC and the other two types of parapsoriasis is the fact that in PLC epidermotropic cells are mostly of histiocytic origin, whereas in PeP and PV they are mainly lymphocytes. The electron microscopic findings support the opinion that PLC should not be considered as a type of parapsoriasis and that PeP and PV probably correspond to prelymphoma.

Chronic Disease↗

Clonal T cell receptor gamma-chain gene rearrangement by PCR-based GeneScan analysis in the skin and blood of patients with parapsoriasis and early-stage mycosis fungoides.

Cutaneous T cell lymphoma (CTCL) and reactive T cell skin diseases represent opposite ends of a spectrum of diseases ranging from overtly malignant to persistently benign. Within this spectrum, the parapsoriasis group is not clearly defined regarding malignant potential. In contrast to consistent findings in advanced-stage CTCL, clonality analysis of parapsoriasis has produced conflicting results in previous studies. As T cell receptor gamma-chain polymerase chain reaction GeneScan analysis (TCR-gamma-PCR-GSA) stands out by its sensitivity, its accuracy in size determination of PCR products, its capacity to identify false positives by repeated analysis and its easy applicability, this approach was used to analyse the clonality status of 41 patients with borderline T cell lymphoproliferative skin diseases, including parapsoriasis (n=27) and early-stage mycosis fungoides (MF) (n=14). A monoclonal T cell infiltrate was demonstrated by repeated TCR-gamma-PCR-GSA in lesional skin specimens in 19.2% of parapsoriasis patients and in 66.6% of early-stage MF cases (p=0.013). In peripheral blood, a monoclonal T cell population was found in a similar percentage of parapsoriasis and of early-stage MF patients (26.7% versus 12.5%; p=0.611). A detailed analysis of parapsoriasis subentities, namely small and large plaque parapsoriasis, and parapsoriasis lichenoides, revealed monoclonality in 2(6)/2(5), 3(14)/2(8) and 0(6)/0/(3) of the skin and peripheral blood specimens, respectively. The high detection rate of false positive cases by repeated analysis (20-37.5%) provides a corrected perspective for the high rates of dominant T cell clones found by others in the peripheral blood of such patients. From the results obtained, three major conclusions can be drawn: firstly, CTCL is clearly associated with detection of monoclonality, even in its early stages; secondly, monoclonality is not a prerequisite for potential CTCL precursor entities; and thirdly, recirculating malignant T cells identical to the skin clone are not readily detected in parapsoriasis or early-stage MF, but may rather indicate disease progression.

Adult↗

A retrospective study of the probability of the evolution of parapsoriasis en plaques into mycosis fungoides.

Parapsoriasis en plaque has been suggested to be an early manifestation of mycosis fungoides (cutaneous T-cell lymphoma). We explored the disease course of patients with small plaque or large plaque parapsoriasis in a 26-year retrospective cohort analysis of 105 parapsoriasis patients, who were clinically and histopathologically followed up in Helsinki and Tampere University Hospitals. Eventual later cancers of these patients were verified from the Finnish Cancer Registry. In the small plaque parapsoriasis group, 7 patients (10%) and in the large plaque parapsoriasis group 12 patients (35%), developed histologically confirmed mycosis fungoides during a median of 10 and 6 years, respectively. No significant differences were found regarding the risk of developing mycosis fungoides or the tendency to remission in patients treated with or without phototherapy. Our results show that not only large plaque parapsoriasis, but also small plaque parapsoriasis, as currently defined in textbooks, can progress to mycosis fungoides. The benefits of phototherapy are equivocal in parapsoriasis treatment as far as progression to cancer is concerned.

Adult↗

[The difference forms of "parapsoriasis en plaques". A report of 90 cases (author's transl)].

The term parapsoriasis was used by Brocq (1902) to group a number of conditions previously described under different names. This group has since then been modified, the same conditions being described under separate names and these have led to a great confusion especially between countries. In this study of 90 cases, three types of parapsoriasis en plaques are distinguished. The "parapsoriasis digitiforme" (40 cases) or benign type, or xanthoerythrodermia perstans, or chronic superficial dermatitis is characterized by small, oval or finger-like, yellow or pink patches. The histology is frequently not characteristic, but in a few cases, there is an exocytosis localized "en flammèches" in the epidermis. The condition is usually permanent but none of these cases has progressed to mycosis fongoides. The parapsoriasis "en grandes plaques simples" (25 cases) is characterized by few pink patches (3 to 5), larger than in benign type. In our cases the transformation to poikiloderma atrophicans vasculare is not observed. One of these cases progressed to mycosis fongoides. The "parapsoriasis en grandes plaques poïkilodermiques" (25 cas), or poikiloderma atrophicans vasculare, prereticulotic poikiloderma, atrophic parapsoriasis, parapsoriasis lichenoides, is characterized by large patches, in limited number, showing a reticulated pigmentation and slight atrophy with telangiectasia. Five cases changed into mycosis fongoides and 4 cases showed some symptoms of malignancy; The histologic features are the same in the two last types: sometimes they are non-specific, in numerous cases the picture is characteristic with micro-abscesses or "flammèches"; in some cases there is a dense infiltrate with a clearly defined lower limit: this histologic appearance can be seen in cases without transformation into mycosis fongoides.

Adult↗

Parapsoriasis en plaques: its potential for progression to malignant lymphoma.

BACKGROUND: Parapsoriasis en plaques (large-plaque type) is a premalignant condition capable of developing into cutaneous T-cell lymphoma (CTCL). However, it is not known whether the early stage of CTCL can be distinguished from parapsoriasis en plaques. OBJECTIVE: Our purpose was to determine whether parapsoriasis en plaques can develop into CTCL. METHODS: The clinical appearance, histopathologic features, immunophenotype, DNA rearrangements, and clinical course were analyzed in 20 cases. RESULTS: T-cell receptor beta-chain gene rearrangement was detected in four of the 20 cases. No clinical, histopathologic, or immunohistochemical differences were found between patients with and without gene rearrangement. CONCLUSION: The early stage of CTCL cannot be differentiated from parapsoriasis en plaques by clinical features, histopathologic characteristics, or immunophenotype. Patients with parapsoriasis en plaques exhibit heterogeneous findings, which may include monoclonal proliferation. Patients with long-standing parapsoriasis-like lesions resistant to conventional treatment require careful monitoring for the possible development of cutaneous lymphoma.

Adult↗

[Phototherapy of parapsoriasis].

The effectiveness of photo(chemo)therapy was tested on 69 patients with different forms of parapsoriasis (parapsoriasis guttata, n = 14; pityriasis lichenoides et varioliformis acuta, n = 6; and parapsoriasis en plaques, n = 49). The forms of parapsoriasis differed in their response to phototherapy and in their relapse rates. Whereas parapsoriasis guttata can be regarded as a definite indication for UVA therapy, much higher UVA doses are required for pityriasis lichenoides et varioliformis and the probability of relapses is higher. It was not possible to interrupt the relapsing course of parapsoriasis en plaqes in the majority of patients. Relapses occurred within 7 months in 63.2% of the cases. A healing effect that lasted for more than one year was achieved only in 18 patients.

Adolescent↗

Parapsoriasis and related conditions.

Classification of parapsoriases is revised into a simple practical table. Pityriasis lichenoides (guttate parapsoriasis) is not a type of parapsoriasis. The clinical features of small patch and large plaque parapsoriasis are described in detail. Six clinical varieties of large plaque parapsoriasis and three clinical varieties of exfoliative dermatitis including Sézary syndrome have been clearly recognized as distinctive categories. Histopathology is useful for the diagnosis of parapsoriasis and mycosis fungoides. Sézary cell count is not significant for the diagnosis of Sézary syndrome.

Dermatitis, Exfoliative↗

Differentiation and clonality of lesional lymphocytes in small plaque parapsoriasis.

BACKGROUND: Small plaque parapsoriasis is an idiopathic chronic dermatosis characterized by patches on the trunk and extremities that are often smaller than 5 cm in diameter and that sometimes have a digitate contour. These latter cases are often referred to as digitate dermatosis. Histopathologic examination reveals a mild superficial perivascular lymphocytic infiltrate associated with mild spongiosis and parakeratosis. To characterize this disease more completely, we analyzed the differentiation and clonality of lesional lymphocytes using immunohistologic and molecular biologic methods. OBSERVATIONS: We studied five cases using a frozen-section immunoperoxidase technique. In each case, there was a predominantly CD4+ T-cell infiltrate admixed with CD8+ T cells, Langerhans cells/indeterminate cells, and macrophages. In three cases, the clonality of lesional T cells was studied by denaturing gradient gel electrophoresis of polymerase chain reaction-amplified T-cell receptor-gamma gene rearrangements. Two cases showed a dominant clonal pattern, while one case exhibited a polyclonal pattern. Clinical follow-up disclosed persistent disease in one of the two clonal cases, while lesions in the other clonal case and the polyclonal case gradually resolved. CONCLUSIONS: Our findings indicate that small plaque parapsoriasis is a clinically indolent, histopathologically nonspecific, predominantly CD4+ T-cell-mediated disease that, at least in some cases, contains a dominant T-cell clone. These features put small plaque parapsoriasis into a category with certain other members of the parapsoriasis group, namely, pityriasis lichenoides and lymphomatoid papulosis, which have been shown to be clonal T-cell disorders despite their clinically benign course. It remains to be determined if the dominant T-cell clones identified in some cases of small plaque parapsoriasis can ever be the direct precursors of overt cutaneous T-cell lymphomas.

Adult↗

Identification of T cell in parapsoriasis infiltrates. Use of an anti-human T-cell serum and the immunoperoxidase technique.

"Parapsoriasis" is a term used to include a heterogeneous group of conditions, one variant of which, at least, eventuates in mycosis fungoides in a substantial percentage of cases. The T-cell origin of mycosis fungoides is well established. The lack of similar information on lymphoid cell types in parapsoriasis prompted an immunoperoxidase study using a specific antihuman T-cell serum in a group of seven patients with parapsoriasis. Our findings demonstrated a preponderantly T-cell infiltrate in the categories of parapsoriasis examined.

Adult↗