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HER2 oncogene amplification in extramammary Paget's disease
M Tanskanen1, T Jahkola, S Asko-Seljavaara
1Department of Pathology, Helsinki University and Helsinki University Central Hospital, Finland. maarit.tanskanen@helsinki.fi
Aims:
To study HER2 oncogene amplification and over-expression in skin samples of 23 patients with extramammary Paget's disease (EMP). EMP is a rare intra-epidermal adenocarcinoma, which has been reported to over-express the HER2 oncoprotein.
Methods And Results:
HER2 gene amplification, detected by chromogenic in-situ hybridization, was found in 43% (10/23) of the lesions. HER2 protein over-expression (3+ immunostaining intensity) was found in 12 tumours (52%), including all 10 tumours with gene amplification. Two tumours showed low-level (2+) HER2 immunostaining. Mammary Paget's lesions, which were used as controls, showed HER2 amplification and over-expression in all 10 cases studied.
Conclusions:
These results indicate that HER-2 protein over-expression in EMP is common and due exclusively to gene amplification. They open up the possibility of HER2-targetted immunotherapy for patients with HER2+ disease.
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