Seborrheic Keratosis

**Semantic type:** Neoplastic Process

**Definition:** A common benign neoplasm usually affecting older individuals. The lesions usually arise in the trunk, head and neck, but they can occur on any skin surface other than the palms, soles, and mucosal surfaces. They appear as flat-based papules or plaques. Histologically, there is intraepidermal proliferation of basaloid keratinocytes, acanthosis, hyperkeratosis, and cysts formation.

**Synonyms:** - Basal Cell Papilloma - Keratosis Seborrheica