<unk>  is one of the most common skin cancers. It is commonly known as rodent ulcer. In 1827, Jacob Arthur, reported the "rodent ulcer". In 1900, Edmund Krompecher, identified the histological features as an epithelial<unk> . The annual incidence of<unk>  in the United States is approximately 2.8 million which increases with increasing age. Men and white skinned people are affected relatively more, especially in states closer to the equator.There is no well established classification for<unk> , however there are few clinical variants which are  nodular, cystic, sclerodermiform, infiltrated, micronodular, superficial, and pigment<unk>  and fibroepithelioma of Pinkus.Although the exact causes were unknown, the following are some of the factors that have been associated with the development of<unk> :  radiation exposure, gene mutations, xeroderma pigmentosa, epidermodysplastic verruciformis, nevoid<unk>  syndrome, bazex syndrome, rombo syndrome etc. Environmental and genetic risk factors that may predispose to<unk>  include radiation exposure, physical characteristics, gender, albinism, xeroderma pigmentosum, epidermodysplastic verruciformis, nevoid<unk>  syndrome, bazex syndrome, rombo syndrome etc. Its morphology is characterized by pearly pink nodules with telangiectasias, rolled borders, and central crusting with or without an ulcerating lesion. The most common cause for the development of the<unk>  involves radiation exposure and mutations that involve many genes including sonic hedgehog gene, PTCH1 gene, and other gain-of-function mutations which further depend on the subtypes such as nodular, superficial, Infundibulocystic, fibroepithelial, morpheaform, infiltrative, micronodular, and basosquamous<unk> s. The U.S. Preventive Services Task Force has found no evidence to recommend for or against screening. It is a slow-growing locally invasive lesion with an unlikely risk of metastasis. Most patients are often asymptomatic. The major complication is its recurrence and involvement of surrounding structures. With appropriate treatment, the prognosis is usually excellent. The history and symptoms of<unk>  include skin growths on sun-exposed skin, mainly in the form of patches that are shiny, pearly bumps, raised edges with central ulceration. They are fragile and may bleed easily. Skin examination usually show papules, plaques, central ulceration with rolled borders, telangiectasias. Skin biopsy is the diagnostic study of choice for<unk> . After the suspicious lesion is evaluated, the medical therapy is divided based on low-risk and high-risk<unk>  patients. Medical therapy consists of topical and systemic therapy. Among topical therapy imiquimod, photodynamic therapy, 5-fluorouracil are included. Systemic therapy consists of sonic hedgehog pathway inhibitors like vismodegib, sonidegib. Types of surgery for<unk>  involve electrodesiccation and curettage, surgical excision, mohs micrographic surgery, and cryosurgery. The primary prevention of<unk>  involves avoidance and protection from the sun like using sunscreen lotions, protective clothing, avoid tanning beds etc. A skin biopsy and chemotherapeutic agents such as 5-Fluorouracil or Imiquimod may prevent the further development of<unk> .
Basal cell carcinoma
Trichoepithelioma
Actinic keratosis
Lymphoepithelioma
Angiokeratoma
Medulloepithelioma
Merkel cell cancer
Pyogenic granuloma