nonmelanoma

Nonmelanoma refers to skin cancers that are not melanoma. In common medical usage, it primarily denotes nonmelanoma skin cancers (NMSC), especially basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). These cancers arise from epidermal keratinocytes or related structures and are the most frequently diagnosed skin cancers worldwide.

BCC is usually slow-growing and unlikely to metastasize, while SCC is more prone to invasion and, in some cases, metastasis. The risk of aggressive behavior is increased in high-risk locations, large or neglected lesions, chronic wounds, immunosuppressed individuals, and certain genetic conditions.

Risk factors include chronic ultraviolet exposure from sun or tanning beds, fair skin, older age, male sex, immunosuppression, arsenic exposure, prior radiotherapy, and certain genetic syndromes. Clinically, BCC often presents as a pearly, translucent papule with telangiectasia; SCC tends to be a scaly, crusted, or ulcerated lesion. Diagnosis is established by biopsy with histopathology; imaging is reserved for advanced cases or suspected metastasis.

Treatment depends on tumor type, size, location, and patient factors. Options include surgical excision with appropriate margins, Mohs micrographic surgery for facial or other high-risk lesions, curettage with electrodessication, cryotherapy, and radiotherapy. Superficial or selected cases may use topical therapies such as 5-fluorouracil or imiquimod; advanced basal cell carcinoma may be treated with hedgehog pathway inhibitors.

Prognosis is generally favorable with early detection and treatment. BCC has a very low metastatic potential, whereas SCC carries a higher risk of recurrence and regional spread. Regular skin examinations and sun protection help reduce the risk of new lesions and improve outcomes. Nonmelanoma must be distinguished from melanoma due to distinct biology and management.