Sir,

Bowen’s disease (BD) is a squamous cell carcinoma (SCC) in situ with a 3–5% risk of progression to invasive SCC [1]. Several treatment modalities are described, including topical chemotherapies, surgical excision, photodynamic therapy (PDT), and destructive therapies. The choice depends on several factors, such as location, size, and scarring ransom [2]. PDT is a non-invasive, highly effective, and aesthetic therapeutic modality for BD [2,3]. It is indicated in non-surgical candidates, patients who have failed and/or cannot tolerate conventional therapies and in cases of extensive (> 3 cm²), multiple or localized lesions on sites with defective healing or on functional locations, such as digital and penile lesions [2,3]. Adaptation to the absorption spectrum of protoporphyrin IX (PpIX) allows the use of IPL as a light source for PDT, with the advantages of high efficacy, minimal discomfort, rapid treatment, and short recovery times [4]. Studies have shown PDT to be as effective or more effective than conventional therapies such as 5-fluorouracil (5-FU) and cryotherapy in treating BD [3]. Clinical complete clearance rates of 88–100% have been reported at three months after one cycle of MAL-PDT [1] and 71% at twenty-four months [5]. However, one study showed that the probability of treatment failure at five years was more than two times higher than after surgical excision, whereas there was no statistically significant difference between 5-FU and PDT [6]. The pretreatment of lesions with ablative lasers, including Er: YAG, resulted in an improvement in both clinical response rate and recurrence rate [3,5], with a five-year clearance rate of 85% vs. 45% with PDT alone [5]. In addition, the therapeutic effect of PDT may also be enhanced by sequential use with topical imiquimod [5]. In any case, regular long-term follow-up of the lesions is necessary to monitor recurrences, which are often small and easy to treat if detected early [3].

Herein, we report the case of an 82-year-old male who consulted for histologically confirmed Bowen’s disease evolving for one year. An examination revealed an erythematous plaque with a verrucous and crusty surface of about 8 cm in the hypogastric region (Fig. 1a) with glomerular vascularization and peripheral, brown, structureless areas on dermoscopy (Fig. 1b). The patient received a combined treatment initially with two sessions of PDT two weeks apart with pretreatment by fractionated Er: YAG laser (energy: 160 J/cm2; ablation depth: 256 mm; density: 30%), followed by the application of methyl aminolevulinate (MAL) and then after 2h of incubation, irradiation by IPL (fluence: 9 J/cm2, double pulse mode, pulse duration: 2.5 ms with a handpiece with a wavelength of 555 nm). He was then put on topical imiquimod five days a week for only one month and then stopped following the appearance of an irritation. At a control three months later, we noted the persistence of some erythematous papules with the same dermoscopic characteristics on a dyschromic scar, hence the realization of two other additional sessions at a fifteen-day interval. The patient was seen again one month later with the total disappearance of the active clinical (Fig. 2a) and dermoscopic lesions (Fig. 2b).

	Figure 1: (a) Erythematous plaque with a crusty surface measuring approx. 6 cm in length in the hypogastric region. (b) Dermoscopy: patchy glomerular vascularization, yellowish crusts, and peripheral, brown, structureless areas.
	Figure 2: Total disappearance of the active (a) clinical and (b) dermoscopic lesions after four sessions of Er: YAG laser-PDT activated by IPL.

REFERENCES

1.Morton CA, Birnie AJ, Eedy DJ. British Association of Dermatologists’guidelines for the management of squamous cell carcinoma in situ (Bowen’s disease). Br J Dermatol. 2014;170:245-60.

2.Palaniappan V, Karthikeyan K. Bowen’s disease. Indian Dermatol Online J. 2022;13:177-89.

3.O’Connell KA, Okhovat JP, Zeitouni NC. Photodynamic therapy for Bowen’s disease (squamous cell carcinoma in situ) current review and update. Photodiag Photodyn Ther. 2018;24:109-14.

4.Piccolo D, Kostaki D. Photodynamic therapy activated by Intense Pulsed Light in the treatment of nonmelanoma skin cancer. Biomedicines. 2018;6:18.

5.Morton CA, Szeimies RM, Basset-Seguin N, Calzavara-Pinton P, Gilaberte Y, Haedersdal M, et al. European Dermatology Forum guidelines on topical photodynamic therapy 2019 Part 1:Treatment delivery and established indications:Actinic keratoses, Bowen’s disease, and basal cell carcinomas. JEADV. 2019;33:2225-8.

6.Jansen MH, Appelen D, Nelemans PJ, Winnepenninckx VJ, Kelleners-Smeets NWJ, Mosterd K. Bowen’s disease:Long-term results of treatment with 5-fluorouracil cream, photodynamic therapy or surgical excision. Acta Derm Venereol. 2018;98:114-5.