A Closer Look at Two Common Types of Skin Cancer
The start of the "sun-worshipping season" is a good time to review the basics of basal cell and squamous cell carcinomas.
A Closer Look at Two Common Forms of Skin Cancer
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.