IEC is a type of squamous cell skin cancer but one that is confined only to the upper layer of skin (epidermis) – and is therefore fairly easys to treat. The abnormal squamous cells of an IEC are located throughout the epidermis. The IEC starts life as a Solar Keratosis – when the abnormal squamous cells involve only the lower part (base) of the epidermis.
With time, an IEC may develop into an Invasive Squamous Cell Carcinoma (SCC) – when these cancerous squamous cells haveespread down into the dermis.
So an IEC is intermediate between the ubiquitous Solar Keratosis, and an invasive Squamous Cell Carcinoma. An IEC is a “proper” skin cancer whereas the solar keratosis is, in effect, a “pre-cancer.”
All three of these lesions share the characteristic of sun damaged epithelial cells (keratinocytes) of the Epidermis (upper layer of the skin) caused by sun damage.