A 66-year-old farmer presents with new growths on his scalp (Figure 171-1). The patient admits to lots of sun exposure and has already had one squamous cell carcinoma (SCC) excised from the scalp 5 years ago. On close inspection there are many suspicious areas for SCC (Figure 171-1). Figure 171-2 demonstrates a shave biopsy of a SCC on a scalp using a dermablade. The pathology demonstrated that 2 of 3 biopsy sites were positive for SCC (E and G were SCC and F was read as actinic keratoses). The patient was referred for Mohs surgery. The Mohs surgeon recommended field treatment with 5-fluoruracil for 4 weeks before surgery to minimize the amount of cutting that would be needed to clear the SCC from this diffusely sun-damaged scalp.
Multiple squamous cell carcinomas on the scalp of a farmer with a lot of sun exposure. The pathology demonstrated that 2 of 3 biopsy sites were positive for squamous cell carcinoma (E and G were squamous cell carcinomas and F was read as actinic keratosis). (Courtesy of Richard P. Usatine, MD.)
Shave biopsy of a squamous cell carcinoma on the scalp. (Courtesy of Richard P. Usatine, MD.)
Cutaneous SCC is the second most common cancer in humans and arises most often as a result of cumulative sun damage. Although the mortality is declining, incidence is increasing in all populations making this cancer a common and significant burden on patients.
- Mortality from SCC has been observed as 0.29 per 100,000 population.1
- Metastasis from SCC occurs in 2% to 9.9% of cases.2
- The incidence is increasing in all age groups and populations at a rate of 3% to 10%.2
- In the United States, approximately 2500 people die from SCC every year.3
- SCC is the second most common skin cancer and accounts for up to 25% of nonmelanoma skin cancers.4
- More than 250,000 new cases of invasive SCC are diagnosed annually in the United States.4
SCC is a malignant tumor of keratinocytes. Most SCCs arise from precursor lesions called actinic keratoses. SCCs usually spread by local extension but are capable of regional lymph node metastasis and distant metastasis. Human papillomavirus (HPV)-related lesions may be found on the penis, labia, and perianal mucosa, or in the periungual region or elsewhere associated with immunosuppression.5
SCCs that metastasize most often start on mucosal surfaces and sites of chronic inflammation.
- Long-term cumulative UV exposure is the greatest risk factor.
- Childhood sunburns.
- Occupational exposure.
- Other UV exposure including PUVA therapy and tanning beds.
- HPV exposure.
- Exposure to ionizing radiation.
- Arsenic exposure.
- Fair skin.
- Age older than 60 years.
- Male gender.
- Living at lower latitude and higher altitude....