CASE #2: Basal cell carcinoma
Basal cell carcinoma (BCC) is a tumor developing from the basal layer of the epidermis. It is the most common type of skin cancer, with a higher of incidence in men than women.8 In the United States, the incidence rates have been estimated between 146 and 317 per 100,000,9 and the rates appear to be increasing. The median age at diagnosis is 68 years with incidence rates increasing with age.10
UV light exposure correlates directly with the incidence of BCC.11 Interestingly, intermittent recreational sun exposure—more so than cumulative UV radiation—seems to be more important in the pathogenesis of this tumor. Sun exposure early in life also appears to have a greater influence on the development of skin cancer. Patients with fair skin are at a higher risk for UV damage and thus for developing BCCs.
The development of BCCs is thought to be attributable to inactivating mutations in the PTCH gene, a tumor-suppressor gene important in controlling proliferation and differentiation of cells.12 Gorlin syndrome, an autosomal dominated inherited disorder with mutations in the PTCH gene, is characterized by the development of BCCs early in life. UV radiation also leads to mutations in p53, likely further contributing to the development of BCCs.
BCCs can present with varying clinical morphologies. The classic presentation is a pink, pearly nodule with telangiectasia, rolled borders, and central ulcer. However, BCCs may also present as erythematous plaques, subcutaneous nodules, and poorly healing ulcers. One variant, pigmented BCCs, may have flecks of pigment or be completely pigmented, making differentiation from a nodular melanoma difficult.
The prognosis of BCC is generally excellent. Metastases and death from this tumor are exceedingly rare, although the destructive growth of the tumor can lead to significant morbidity if not diagnosed and treated correctly.
Treatment revolves around excision or destruction of the tumor. Standard surgical excision is effective for most primary BCCs. Mohs micrographic surgery allows for histologic confirmation of tumor removal with low recurrence rates and is the preferred surgical modality for certain subtypes of BCC and tumors in high-risk locations. For selected smaller lesions, tumor destruction by curettage and electrodessication can be done quickly and yield high cure rates. Topical therapies can also be utilized for superficial BCCs. All patients, especially those with a history of skin cancer, should undergo a thorough skin screening and be counseled on sun protection.
This patient underwent excision of the BCC without complication. On follow-up over the next two years, no subsequent skin cancers developed.
Dr. Chan is a resident in the department of dermatology, Baylor College of Medicine, in Houston. He has no relationships to disclose relating to the content of this article.
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All electronic documents accessed May 15, 2010.