Spinocellular carcinoma

Most spinocellular carcinoma (SCC) cases occur among elderly patients after sun exposure. In younger patients, it can appear on any skin or mucous surface, especially among those with light skin that easily get sunburnt. The most common tumors are in areas exposed to the sun, such as the scalp, face and especially the lower lip, ear, tongue and the back of the hand. Repeated trauma associated with certain occupations can lead to the appearance of spinocellular carcinoma in other areas. Primary cutaneous spinocellular carcinoma is a malignant neoplasm of keratinous epidermal cells. Unlike basal cell carcinoma, which has a very low metastatic potential, SCC can metastasize and grow rapidly. The clinical symptoms of SCC vary widely. Commonly, SCC appears as an ulcerated nodule or as a superficial erosion on the skin or lower lip but may also present as a papule or warty plaque. Unlike basal cell carcinoma, telangiectasias are rare. The margins of this tumor may be weakly delimited and adhesion to the underlying structures may occur. SCC can appear anywhere on the body, but frequently occurs on the skin damaged by the sun (forehead, face, ear, scalp, neck and back of the hand). A related neoplasm, keratoacanthoma, typically appears as a dome-shaped papule with a central keratotic crater, rapidly spreading and regressing without therapy, usually. This lesion can be difficult to differentiate from SCC. SCC has several premalignant forms (actinic keratosis, actinic cheilitis) and in situ forms (eg, Bowen’s disease) that are limited to the epidermis. Keratosis and actinic cheilitis are hyperkeratotic papules and plaques that appear in areas exposed to the sun. While the potential for malignant degeneration is low for any individual lesion, the risk for SCC increases the larger the number of lesions is. Bowen’s disease presents as an erythematous-crustal plaque that can turn into invasive SCC in about 20% of cases. There is controversy regarding the association of Bowen’s disease with internal malignancies; however, recent data suggest that there is no significant relationship when other predisposing factors (eg, arsenic) are absent. Treatment of premalignant and in situ lesions reduces the subsequent risk of invasive disease.

The evolution of skin carcinomas

Most squamous cell carcinomas are only locally aggressive, but they can be cured by various methods. SCC in immunocompromised patients (including those infected with HIV) is usually more aggressive. Tumors with deep invasion, poor differentiation, perineural invasion and acantolytic features may recur or metastasize more frequently. Narrow safety margins during carcinoma excision are another risk factor for recurrences. The context in which SCC occurs also influences the risk of metastasis, for example: tumors on skin exposed to sunlight have a metastasis rate of less than 0.5%, while tumors developed on skin not exposed to the sun have a risk of metastasis of 2-3%. The risk also increases in tumors arising from the development of Bowen’s disease, tumors of the lip, vulvar, perineal and penile region and in Marjolin ulcers, radiated scars or burns. Spinocellular carcinomas less than 2 mm thick metastasize very rarely, those between 2-5 mm have an intermediate risk of metastasis (approximately 5%), and those over 5 mm have a 20% risk of metastasis. Tumors larger than 2 cm in diameter reappear and metastasize more frequently than small lesions.