PARAPSORIASIS-EN-PLAQUES - ITS POTENTIAL FOR PROGRESSION TO MALIGNANT-LYMPHOMA

Background: Parapsoriasis en plaques (large-plaque type) is a premalig nant condition capable of developing into cutaneous T-cell lymphoma (C TCL). However, it is not known whether the early stage of CTCL can be distinguished from parapsoriasis en plaques. Objective. Our purpose wa s to determine whether parapsoriasis en plaques can develop into CTCL. Methods: The clinical appearance, histopathologic features, immunophe notype, DNA rearrangements, and clinical course were analyzed in 20 ca ses. Results. T-cell receptor beta-chain gene rearrangement was detect ed in four of the 20 cases. No clinical, histopathologic, or immunohis tochemical differences were found between patients with and without ge ne rearrangement. Conclusion: The early stage of CTCL cannot be differ entiated from parapsoriasis en plaques by clinical features, histopath ologic characteristics, or immunophenotype. Patients with parapsoriasi s en plaques exhibit heterogeneous findings, which may include monoclo nal proliferation. Patients with long-standing parapsoriasis-like lesi ons resistant to conventional treatment require careful monitoring for the possible development of cutaneous lymphoma.