Author: Assoc Prof Patrick Emanuel, Dermatopathologist, Auckland, New Zealand, 2013.
Eccrinecarcinoma is a rare tumour that typically presents as a slow growing plaques or nodules on the scalp but can arise at other sites.
Histology of eccrinecarcinoma
Sections of eccrinecarcinoma show a tumour composed of basaloid cells infiltrating the dermis (figure 1). The tumour forms tubules and glands (figures 2-4) which infiltrate a sclerotic dermis. Eccrine differentiation is readily seen at high power (best seen in figures 2 and 3). Clear cell change may be seen (figure 4).
Immunohistochemical studies can be used to demonstrate glandular differentiation (CEA) in eccrinecarcinoma, but are not needed if the morphology is classic. Some cases resemble breast cancer. Focal p63 and CK5/6 positivity is thought to favour a primaryeccrinecarcinoma.
Differential diagnosis of eccrinecarcinoma
Metastatic breast cancer – Clinical correlation may be needed to distinguish primaryeccrinecarcinoma from metastatic breast carcinoma. Immunohistochemical studies (see above) can be helpful
Microcystic adnexal carcinoma (MAC) – Some authors consider eccrinecarcinoma to be a form of MAC. MAC generally demonstrates some squamous differentiation and keratinizing cystic changes superficially.
Pathology of the Skin (Fourth edition, 2012). McKee PH, J. Calonje JE, Granter SR