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Mutator phenotypes with microsatellite instability (MSI) correlated with defects in the mismatch repair system are characteristic for a subset of solid neoplasms, but are rare in non-Hodgkin lymphomas. In mismatch repair-deficient mice, however, mutator-type non-Hodgkin lymphomas are the most frequent tumors. To determine the role of MSI in mycosis fungoides, we compared the states of the eight dinucleotide microsatellite loci DXS418, DXS453, DXS556, DXS1060, D1S201, D6S260, D9S162, and D10S215 in tumor cells of 12 well-characterized patients at early- and advanced-stage diseases to matched healthy tissue. We did not find any MSI, although all but one patient had progressed to advanced-stage disease within the timeframe of the study. Concordantly, the expression of mismatch repair genes was normal. These results suggest that progressive accumulation of mutations as detected by MS analysis does not play a major role in the pathogenesis or in the progression of mycosis fungoides.Journal of Investigative Dermatology (2007) 127, 1752–1761; doi:10.1038/sj.jid.5700793; published online 29 March 2007 [ABSTRACT FROM AUTHOR]

Lymphomatoid papulosis (LyP), primary cutaneous anaplastic large T-cell lymphoma (cALCL), and cutaneous infiltrates of systemic anaplastic large cell lymphoma (sALCL) are CD30-positive lymphoproliferative disorders of the skin that overlap clinically, histopathologically, immunophenotypically, and genetically but differ considerably in their prognosis. In particular, lesions of LyP regress spontaneously, whereas those of cALCL and sALCL persist and may progress and spread to extracutaneous sites. In contrast to patients with cALCL, LyP patients do not benefit from an aggressive radio- and/or chemotherapeutic approach. We generated a novel tumor necrosis factor receptor (TNFR)-associated factor 1 (TRAF1) antibody that recognizes a formalin-resistant epitope (Ber-TRAF1A) and investigated the expression of TRAF1, an intracellular component of TNFR signaling, in LyP and ALCL. We could show a strong TRAF1 expression in the tumor cells of most LyP cases (42/49, 84%). In contrast, tumor cells of primary and secondary cALCL revealed TRAF1 expression in only a few cases (3/41, 7%) as shown for sALCL without skin manifestation. The data indicate that TRAF1 expression reliably distinguishes LyP from primary or secondary cALCL. This might be of crucial diagnostic importance and has a strong impact on the treatment decision for patients with cALCL and LyP.Journal of Investigative Dermatology (2007) 127, 1898–1904; doi:10.1038/sj.jid.5700800; published online 29 March 2007 [ABSTRACT FROM AUTHOR]

Detection of a clonal T cell receptor (TCR) gene rearrangement is used in the diagnosis of primary cutaneous T cell lymphomas (CTCL) whereas chromosomal aberrations serve as a diagnostic tool for leukaemias and nodal lymphomas. To what extent both approaches specify the same cell population remains unknown. We investigated the coincidence of TCR clonality with complex clonal chromosomal aberrations, indicating qualitative alteration of the affected cells, in 17 CTCL patients. Out of 41 skin, blood, and lymph node samples studied, 34 gave results in chromosome and TCR analyses. With 88%, most specimens revealed corresponding results by both techniques (27 of 34 clonal, three of 34 non-clonal). In two patients, analysis of micro-dissected cells demonstrated that neoplastic T cells bear both a dominant TCR rearrangement and a complex chromosomal aberration. The cutaneous clone was found in blood samples of 11 of 12 patients (including early stages), and investigation of follow-up skin and blood samples indicated persistence of the T cell clone in 11 of 14 cases. In conclusion, we show that dominant TCR clones and chromosomal clones converge in all stages of CTCL. These clones disseminate into blood and skin at early disease stages and persist despite therapy. The coexistence of a dominant TCR clone and a clonal chromosomal aberration can thus be used as a hallmark of malignancy. [ABSTRACT FROM AUTHOR]