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.

HCR, a candidate gene for psoriasis, is expressed differently in psoriasis and other hyperproliferative skin disorders and is downregulated by interferon-gamma in keratinocytes.

We have previously shown that HCR is a good candidate gene for psoriasis based on its location in the PSORS1 locus, predicted secondary structure change of the associated allele, and expression pattern. To understand better the function of HCR, we studied how HCR expression is altered in hyperproliferative skin diseases other than psoriasis and in cancers. We examined also its regulation by different cytokines, growth factors, and antipsoriatic agents using quantitative RT-PCR (TaqMan) analysis and its location by immunostaining of keratinocyte cultures.

Matrix metalloproteinase-19 is expressed by keratinocytes in psoriasis.

Keratinocyte hyperproliferation, inflammatory infiltrates, neoangiogenesis and alterations in cytokine levels are hallmarks of psoriatic skin. Matrix metalloproteinases (MMPs) have been associated with the remodeling of the extracellular matrix during inflammation, neovascularization, and malignant transformation. We have previously shown that particularly MMP-12 is abundantly expressed by macrophages and MMP-9 in macrophages and neutrophils of psoriatic lesions.