There are a variety of routine and immunohistochemical stains used to diagnose mammary and extramammary Paget's disease (MPD and EMPD). Most of the stains commonly used, however, show a positive reaction in the Paget's cells in all cases. We wanted to assess which immunohistochemical stain is the best for the diagnosis of MPD and EMPD, as well as the best stain for identifying small foci of tumors in evaluating tumor margins. We evaluated nine cases of MPD and nine cases of EMPD, which were randomly chosen, with a battery of immunohistochemical stains. These stains included cytokeratin 7, cytokeratin 20, carcinoembryonic antigen, Ber-EP4, and CAM 5.2. Cytokeratin 7 was the only immunohistochemical stain that stained all of the cases diffusely, and, in all of the cases, the staining of the Paget's cell was intense and specific within the epidermis. We concluded that cytokeratin 7 is the immunohistochemical stain of choice in the diagnosis of Paget's disease. Because cytokeratin 7 seems to identify single cells, it might also be valuable in evaluating surgical margins for small foci in a tumor such as EMPD, which might have a multifocal origin.

Expression of the p38 MAPK, NF-kappaB and cyclin D1 in extramammary Paget's disease.J Dermatol Sci. 2007 Mar;45(3):187-92. Epub 2007 Jan 5.

BACKGROUND: The p38 mitogen-activated protein kinase (MAPK)/nuclear factor kappaB (NF-kappaB)/cyclin D1 signaling pathway has recently been shown to play an important part in the pathogenesis of many human tumors. However, the role of this signal transduction pathway in extramammary Paget's disease (EMPD) remains unknown. OBJECTIVE: This study was designed to investigate the expression of phosphorylated p38 MAP kinasealpha (p-p38 MAPKalpha), phosphorylated NF-kappa B p65 (p-NF-kappaB p65) and cyclin D1 proteins in EMPD and to evaluate the relationship among them. METHODS: Thirty-five tissue samples from 30 primary EMPD cases were analyzed by immunohistochemical staining in formalin-fixed, paraffin-embedded tissue sections for p-p38 MAPKalpha, p-NF-kappaB p65 and cyclin D1. RESULTS: Among the 35 specimens of EMPD, p-p38 MAPKalpha, p-NF-kappaB p65 and cyclin D1 were expressed in 30, 28 and 27, respectively. Moreover, in five metastatic lymph node specimens, all were positive for p-p38 MAPKalpha and p-NF-kappaB p65, four were positive for cyclin D1. There were significant correlations between expression of p-p38 MAPKalpha, p-NF-kappaB p65, and cyclin D1 in EMPD. CONCLUSION: This study provides evidence that p-p38 MAPKalpha, p-NF-kappaB p65, and cyclin D1 was overexpressed in EMPD, suggesting that the p38 MAPK/NF-kappaB/cyclin D1 signaling pathway might participate in the oncogenesis of EMPD.