What Are the Two Most Common Skin Cancers?
According to the American Cancer Society, skin cancer is the most common cancer in the United States.1 While melanoma is the deadliest form of skin cancer, basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) are much more common.
BCCs account for approximately 80% of all skin cancers.2 These epithelial tumors develop from basal cells, located in the lower layer of the epidermis. BCCs are slow-growing and rarely metastasize. They are seen most frequently, but not exclusively, in fair-skinned individuals with a history of actinic exposure.
The most common sites of BCC are sun-exposed areas such as the face, ears, and chest. The majority of BCCs—70%—occur on the face, particularly on the nose.2 Another 25% of BCCs occur on the trunk or the extremities, and the remaining 5% on the penis, vulva, or perianal skin, suggesting that there is more to the development of BCC than simply actinic exposure, although actinic exposure is carcinogenic and can lead to mutations directly related to the development of BCCs.
Clinical appearance. BCCs can have various presentations, with the most common being a pearly papule with telangiectases in the lesion and a rolled edge. These tumors often bleed. Many patients present with a chief complaint of a nonhealing pimple.
The pathology of these classically appearing BCCs are reported as "nodular" BCCs on histologic analysis. Infiltrative BCCs often appear clinically the same as nodular BCCs; however, infiltrative BCCs are difficult to read at the margins because they do not have distinct borders under the microscope.
This makes treatment more challenging. Micronodular BCCs have a more distinct border both to the naked eye and under the microscope, and appear as classically described but tend not to ulcerate.
Three forms of BCC can have a more variable clinical appearance that makes diagnosis difficult: morpheaform BCC, pigmented BCC, and superficial BCC.
Morpheaform BCC appears yellowish and waxy with a tinge of pink, and is often more sclerotic, lacking any ulcercation. These lesions often feel firm on palpation. This finding illustrates the point that a skin examination is often tactile as well as visual.
Pigmented BCC resembles a traditional BCC but has specks of pigment in it, giving it an almost peppered appearance.
Superficial BCC can be much more subtle and appear as an erythematous patch or plaque with or without scale. Superficial BCC occurs most commonly on the upper trunk and shoulders. These lesions are easily misdiagnosed or overlooked as being an eczema patch or psoriasis patch.
A superficial BCC should be considered in the differential diagnosis if a patient presents with red, flaky patches, particularly if that patient has a history of significant sun exposure. Any person with a history of significant sun exposure should be a candidate for a complete skin examination with a dermatology professional.
Diagnosis. The diagnosis of a BCC is made by biopsy. A shave, tangential, or saucerization biopsy is adequate to make the diagnosis and treatment plan. A punch biopsy can be performed if a melanoma is in the differential diagnosis.
Treatment. BCCs typically are treated surgically. Surgical options include excision with appropriate margins, electrodesiccation and curettage (ED&C), and Mohs micrographic surgery. ED&C, the most commonly performed treatment, is done only after the lesion has been debulked during biopsy.