immunosuppression had an increased risk for developing SCC-SK particularly when inhibition was transplant associated. The SCC-SK arises most commonly on the head and neck of elderly immunosuppressed men. Roh determined that the second most common diagnoses mistaken for SK was verruca plana (VP) at 15.4%.12 VP are benign epithelial proliferation that presents as slightly elevated, flat-topped papules with minimal scale. Kim designed a diagnostic algorithm to distinguish VP and VP-like SKs based on clinical and dermoscope criteria.26 The algorithm proposed by Kim suggests evaluation of the skin for Koebner’s phenomenon (diagnostic of VP), then dermatoscopy (distinguishing VP from VP-like SK). If a diagnosis is not made, the next step is evaluation of the distribution of each lesion (distinguishing VP from VP-like SK). If a diagnosis is not made after these three steps, then a biopsy is recommended. Treatment Dermatologists reportedly manage 85% of all episodes of SKs and they managed 89% using low intensity procedures.27 Dermatologists had the highest diagnostic accuracy for SKs and were more likely than general or plastic surgeons to perform acceptable management procedures. The therapeutic armamentarium for the treatment of SKs is primarily procedural. Effective low intensity procedures include curettage, electrodessication, cryosurgery, chemical, and laser destruction. Unfortunately, recurrence, scarring, and pigmentation changes are common problems with these techniques particularly in the skin of color population. Topical treatment with cryosurgery, tazarotene 0.1% cream, calcipotriene 0.005% ointment, and imiquimod, have been studied with only cryosurgery demonstrating complete resolution of SKs and twice daily tazarotene 0.1% cream resulting in improvement in 7 of 15 patients.28 Gurel compared the efficiency of Er:YAG lasers with cryotherapy in the treatment of SK and reported complete healing in 100% of the lesions treated with Er:YAG lasers compared to 68% for the cryotherapy group.29 In the Er:YAG laser-treated group, hyperpigmentation was significantly lower but more erythema developed than in the cryotherapy group. FGFR3 mutations have been implicated in the development of SKs. Dobesilate interferes with the FGF signals and a 5% potassium dobesilate cream daily for 6 months was applied to 2 SKs on the face. Dobesilate achieved complete clearance of the SK lesions with good cosmetic results, and the authors suggested that this compound is a safe and efficient candidate in the treatment of SK.30 Additional new compounds being studied for the treatment of SK include aqueous BL-5010 (trichloroacetic acid and formic acid) applied to at least one SK on the face, scalp, trunk, or extremities and A-101 (hydrogen peroxide formulation) 40% Topical Solution applied to four target SKs on the face, trunk, and extremities.31,32 A phase 1/2 trial of BL-5010 enrolling 60 subjects reported that 90% of subjects had complete remission and 7% partial remission of SKs at trial completion.31 Adverse events included irritation, itching, and burning at the application site, bleeding, and scale crust formation. Two phase 3 trials of A-101 enrolling 937 subjects reported that 51.3% of lesions treated with A-101 were clear or near clear at trial completion versus 7.3% of lesions in the placebo group.32 65.3% of lesions on the face treated with A-101 were clear or near clear versus 10.5% of lesions in the placebo group. 13.5% and 23.0% of patients in the two trials treated with A-101 achieved clearance of at least three of the four target SK lesions as compared to no placebo subjects. The compound was well tolerated with hypopigmentation, hyperpigmentation, and scarring graded as mild.
The SKs is a commonly occurring often asymptomatic lesion that is diagnosed and treated by dermatologists. Gaps exist in medical knowledge concerning this benign lesion. The etiology and pathogenesis of the SK is being elucidated with several oncogenic mutations identified. Lesions are diagnosed clinically and the differential diagnosis included both benign and malignant lesions. Melanoma is the most concerning mimicker of the SK. SKs impact the QOL of patients in a variety of ways and financial concerns often impact the ability to have these lesions treated. Treatment of SKs is primarily procedural with new treatments being developed.
Dr. Susan Taylor is an advisory board member and investigator for Aclaris Therapeutics, Inc.