Monoclonal islet antibody HISL-19 as a tool in the diagnosis of neuroendocrine carcinomas of the skin.

The monoclonal islet cell antibody HISL-19 generated after immunization of BALB/c mice with human pancreatic islet cell preparations, demonstrated specific immunoreactivity for neuroendocrine (Merkel) cells of the skin as shown by successive and simultaneous localization of neuron-specific enolase and the antigen detected by mab HISL-19 in the same cells of the bovine epidermis. Following these observations, we tested nine neuroendocrine carcinomas of the skin that were believed to be of Merkel cell origin for their immunoreactivity with mab HISL-19 using an indirect immunoperoxidase technique on formalin-fixed and paraplast-embedded tissues. In contrast to malignant lymphomas, poorly differentiated squamous cell carcinomas, and malignant melanomas, all nine neuroendocrine carcinomas reacted strongly with mab HISL-19, indicating its potential as a useful immunohistochemical probe for the distinction of neuroendocrine carcinomas of the skin from other cutaneous neoplasms with similar histological appearance.