Pseudoepitheliomatous hyperplasia in cutaneous T-cell lymphoma. A clinical, histopathological and immunohistochemical study with particular interest in epithelial growth factor expression

Pseudoepitheliomatous hyperplasia has occasionally been reported in cutaneo us T-cell lymphoma (CTCL). This association raises the question of the rela tionship between epidermal hyperplasia and the lymphomatous infiltrate. Bec ause epidermal growth factor (EGF) and transforming growth factor-alpha (TG F-alpha) have been demonstrated to be involved in epidermal proliferation t hrough binding to EGF receptor (EGFr), we tested the hypothesis that these cytokines could be secreted by lymphomatous cells, and induce the overlying pseudoepitheliomatous hyperplasia. The purposes of this study were: (i) to describe the clinical and immunohistological features of pseudoepithelioma tous hyperplasia; (ii) to determine its frequency in a large series of CTCL s; and (iii) to evaluate the expression of EGF, TGF-alpha and EGFr in CTCL with or without pseudoepitheliomatous hyperplasia. Eleven cases of CTCL wit h pseudoepitheliomatous hyperplasia were collected from a series of 353 cas es of cutaneous lymphoma registered from 1990 to 1996. They consisted of ei ght of 28 (28.5%) CD30+ large T-cell lymphomas and three of 148 (2%) cases of mycosis fungoides. Epidermal expression of EGF, EGFr and TGF-alpha was s tronger in CTCL than in control normal human skin, Lymphomatous T cells exp ressed EGF and TGF-alpha whereas no expression of these cytokines could be detected in cutaneous and nodal B-cell lymphomas, nor in a normal lymph nod e. In addition, epidermal expression of EGFr was stronger in CTCL with pseu doepitheliomatous hyperplasia than in control cases of CTCL without pseudoe pitheliomatous hyperplasia, suggesting that these cytokines, in association with other factors, are probably involved in the epidermal hyperplasia obs erved in some cases of CTCL.