Dermoscopy revealed a keratotic, 2.5-cm scaly plaque with linearly arranged dotted vessels, ulceration, and shiny white lines. A shave biopsy was consistent with a squamous cell carcinoma in situ (SCC in situ)—a pre-invasive keratinocyte carcinoma.
SCC in situ, also known as Bowen’s disease, is a very common skin cancer that can be easily treated. Lesions may manifest anywhere on the skin but are most often found on sun-damaged areas. Actinic keratoses are a pre-malignant precursor of SCC in situ; both are characterized by a sandpapery rough surface on a pink or brown background. Histologically, SCC in situ has atypia of keratinocytes over the full thickness of the epidermis, while actinic keratoses have limited atypia of the upper epidermis only. With this in mind, suspect SCC in situ (over actinic keratosis) when a lesion is thicker than 1 mm, larger in diameter than 5 mm, or painful.1
Treatment options include surgical and nonsurgical modalities. Excision and electrodessication and curettage (EDC) are both effective surgical procedures, with cure rates greater than 90%.2 Nonsurgical options include cryotherapy, 5-fluorouracil (5FU), imiquimod, and photodynamic therapy. Treatment with 5FU or imiquimod involves the application of cream to the lesion for 4 to 6 weeks. Marked inflammation during treatment is to be expected.
In the case described here, the patient underwent EDC in the office and was counseled to continue with complete skin exams twice a year for the next 2 years.
Photos and text for Photo Rounds Friday courtesy of Jonathan Karnes, MD (copyright retained). Dr. Karnes is the medical director of MDFMR Dermatology Services, Augusta, ME.