Bowen's disease Squamous cell carcinoma in situ. Bowen's disease may occur on mucosal surfaces such as the glans penis. Full thickness dysplasia of the keratinocytes with numerous large atypical cells with bizarre mitoses. These cell grow in groups and strands into the dermis. Characterized by malignant squamous cells that arise from the epidermis.
Moles are the most common tumors.
Junctional nevi are usually flat and deeply pigmented. Intradermal nevi can be nonpigmented with a dome shaped appearance. By definition, congenital nevi are present at birth. They usually remain throughout life. Most congenital nevi are small but a small percentage are very large and are referred to as giant congenital nevi.