Neoplasms of the Skin

Cutaneous squamous cell carcinoma (cSCC) is caused by malignant proliferation of atypical keratinocytes. This condition is the 2nd most common skin malignancy and usually affects sun-exposed areas of fair-skinned patients. The cancer presents as a firm, erythematous, keratotic plaque or papule. Histopathologic examination should be done for all suspected cases, as many lesions, such as actinic keratosis, mimic the appearance of SCC. Surgical excision is the mainstay of treatment. Overall prognosis is excellent for completely excised lesions, but certain high-risk features may predispose to metastatic disease and poor outcomes.

Melanoma is a malignant tumor arising from melanocytes, the melanin-producing cells of the epidermis. These tumors are most common in fair-skinned individuals with a history of excessive sun exposure and sunburns. Melanomas usually present as pigmented skin lesions, but they can occur on mucosal surfaces, such as in the eyes, anal canal, and genital regions. Common findings may include Asymmetry of the lesion, irregular Border, varying Color, > 6 mm Diameter, and Evolving features (ABCDE). Definitive diagnosis is established with biopsy. Treatment relies primarily on surgical excision. The prognosis is very good for early-stage lesions but quite dismal for metastatic disease. Of all the skin malignancies, melanoma generally carries the worst prognosis.

Nevi (singular nevus), also known as “moles,” are benign neoplasms of the skin. Nevus is a non-specific medical term because it encompasses both congenital and acquired lesions, hyper- and hypopigmented lesions, and raised or flat lesions. Additionally, nevi can be found within different depths of the layers of the skin and originate from various types of cells (e.g., melanocytic, connective tissue, vascular). Nevi also have a wide variety of characteristic forms, which must be well understood in order to differentiate nevi from malignant melanoma. In this concept page, we will cover the basic classifications and most common types of nevi as well as the clinical criteria used to assess them.