Two cases of multiple self-healing epithelioma (Ferguson Smith) are reported. Examination of tumor nuclei with the electron microscope revealed intranuclear particles seemingly identical to those which have been described in solitary keratoacanthoma. However, this particle has now been shown by us and others to occur in entirely different cells and circumstances, and therefore cannot be considered justification to support (1) the possible identity of the lesions of multiple self healing epithelioma and those of solitary keratoacanthoma or (2) the possible viral etiology of keratoacanthoma. Our attempts to culture a virus from lesions of these two patients failed. The nature of the particle and the etiology of the disease remain uncertain.