Squamous islands in eccrine neoplasms.

The presence of squamous cells in eccrine neoplasms is not well recognized, but is usually considered to denote malignant transformation. The small nests composed of squamoid cells (squamous islands), however, were found in 46% of the eccrine neoplasms we studied. They were divided into three types according to their location, histological structure, and degree of cellular atypia. These types possibly represented intermingling of epidermis or hair follicle, squamous syringo-metaplasia, and malignant transformation. We would like to stress that squamous islands are seen not only in malignant eccrine neoplasms, but also in benign ones, and that their presence should not be interpreted as evidence of malignancy.