Photodynamic therapy for Bowen's disease (squamous cell carcinoma in situ) of the digit

Surgical excision is the preferred method of eradicating Bowen's disease (BD). However, when BD occurs on the digit, surgical intervention can sometimes lead to scar contracture and loss of function of the digit.

To evaluate the effectiveness of photodynamic therapy (PDT) in eradicating BD of the digit while preserving the full function of the digit.

Four patients of chronic arsenism with biopsy-proven BD on the digit were treated with PDT by using a newly designed light-emitting diode (LED) array with a peak wavelength of 630 nm (630 +/- 40 nm; 40 mW/cm2 at skin surface). After partial removal of the thickened horny layer and 16 hours of occlusion with a 2% aminolevulinic acid (ALA) solution, each lesion was irradiated with 240 J/cm2 in two fractions with a 90-minute interval.

All patients experienced a significant burning, tingling sensation that was tolerable during the procedure except one who needed local anesthesia. All treated digits healed without scarring in 2 weeks. Posttreatment biopsy in one patient showed normal epidermis and a slight fibrosis in the papillary dermis. Three patients remained free of recurrence (75%) at 15-17 months (average 16 months) after one treatment. One patient's BD recurred at 8 months, but was successfully treated without recurrence after 20 months.

Our preliminary study suggests that PDT using 2% 5-ALA solution and an LED array is an effective, noninvasive method to treat digital BD with the benefit of scar-free contracture and loss of digital function. Among the various factors that would affect the results of PDT, we feel that partial removal of the thickened horny layer is the most important step to achieve sufficient therapeutic effect in digital BDs.