Reactivity with TdT in Merkel cell carcinoma: a potential diagnostic pitfall
Am J Clin Pathol. 2008 Jun
Buresh CJ, Oliai BR, Miller RT.
Immunohistochemistry Division, ProPath Laboratory, Dallas, TX 75247, USA.
Merkel cell carcinoma (MCC) is a high-grade neuroendocrine carcinoma of skin characterized by cells with a "blastic" appearance, scant cytoplasm, and fine, evenly distributed chromatin. Terminal deoxynucleotidyl transferase (TdT) is a DNA polymerase present in thymic T cells, lymphoblastic lymphoma/leukemia, and some cases of acute myeloid leukemia. After observing TdT immunoreactivity in a case of MCC, we analyzed 26 tumors by immunohistochemical analysis to determine their spectrum of reactivity with TdT and identified TdT in 19 (73%) of 26 MCCs. Staining intensity was variable but was often moderate to strong and present in a significant percentage of cells. Because MCC has cytomorphologic features similar to those of lymphoblastic lymphoma and may manifest as metastatic disease, reactivity with TdT in MCC could represent a diagnostic pitfall in the differential diagnosis with lymphoblastic lymphoma, particularly because the latter may lack CD45 and/or CD20, yet both neoplasms may express PAX-5, a B-cell-associated marker.
MetaPress American Journal of Clinical Pathology
Tuesday, December 30, 2008
Merkel cell carcinoma: molecular pathogenesis, clinical features and therapy.
Merkel cell carcinoma: molecular pathogenesis, clinical features and therapy.
J Dtsch Dermatol Ges. 2008 Sep
Becker JC, Kauczok CS, Ugurel S, Eib S, Bröcker EB, Houben R.
Department of Dermatology, Venereology and Allergy, University of Würzburg, Germany. becker_jc@klinik.uni-wuerzburg.de
Merkel cell carcinoma (MCC) is a highly aggressive neuroendocrine carcinoma of the skin. The incidence of this rare tumor is increasing rapidly; the American Cancer Society estimates for 2008 almost 1500 new cases in the U.S. Thus, the incidence of MCC will exceed the incidence of cutaneous T-cell lymphoma. Moreover, the mortality rate of MCC with 33% is considerably higher than that of cutaneous melanoma. These clinical observations are especially disturbing as we are only recently beginning to understand the pathogenesis of MCC. For the same reason, the therapeutic approach is often unclear; reliable data are only available for the therapy of locoregional disease.
Wiley InterScience
J Dtsch Dermatol Ges. 2008 Sep
Becker JC, Kauczok CS, Ugurel S, Eib S, Bröcker EB, Houben R.
Department of Dermatology, Venereology and Allergy, University of Würzburg, Germany. becker_jc@klinik.uni-wuerzburg.de
Merkel cell carcinoma (MCC) is a highly aggressive neuroendocrine carcinoma of the skin. The incidence of this rare tumor is increasing rapidly; the American Cancer Society estimates for 2008 almost 1500 new cases in the U.S. Thus, the incidence of MCC will exceed the incidence of cutaneous T-cell lymphoma. Moreover, the mortality rate of MCC with 33% is considerably higher than that of cutaneous melanoma. These clinical observations are especially disturbing as we are only recently beginning to understand the pathogenesis of MCC. For the same reason, the therapeutic approach is often unclear; reliable data are only available for the therapy of locoregional disease.
Wiley InterScience
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