Owing to relatively high recurrence rates and the metastatic potential of squamous cell carcinoma (SCC), there is currently insufficient evidence to support the routine use of topical photodynamic therapy (PDT) for SCC1. Now the advent of second-generation photosensitizers such as chlorine, which are more effective, penetrable and less phototoxic to the skin than their forerunners, makes this treatment a feasible alternative to surgery2.

A 79-year-old woman presented with a 2-year history of recurrent ulcerated lesion on the scalp vertex. There was no history of skin disease or trauma on the affected area. Clinical examination revealed a walnut-sized central crusted ulcer surrounded by erythematous, elevated indurative border (Fig. 1A). The histological features showed invasion of the dermis by irregular masses of epidermal cells that were predominantly mature squamous cells showing relatively slight atypicality. The depth of microscopic invasion was 3 mm. There was no presence of perivascular or perineural invasions (Fig. 2). A diagnosis of well-differentiated SCC was made on the basis of these clinical and histological findings. Because of her age and refusal of surgery, we decided to treat her with chlorine PDT. At first, we considered topical PDT with chlorine. But as the optimal topical agent could not penetrate to the needed full depth, we planned instead systemic chlorine PDT. Pretreatment evaluation included a history and physical examination, routine laboratory evaluation and photographic documentation. She has no photosensitivity and there were no signs to imply any other systemic diseases including internal malignancy. No further systemic workup was performed as is usual with cutaneous SCC. The patient was admitted to the hospital and the photosensitizer Radachlorin® (RADA-PHARMA, Moscow, Russia) was injected intravenously for 30 minutes at a dose 0.9 mg/kg. Laser irradiation was carried out for 2 hours after the injection. As a light source we used a fiber coupled diode laser 'LAHTA-MILON®' (Milon Laser, St. Petersburg, Russia). The lesion was photo-activated by 2.5 W, 662 nm in light doses of 250 J/cm². The patient reported a mild burning sensation during the whole illumination time, but did not ask to interrupt the procedure. Erythema and slight edema were observed immediately after illumination. No serious adverse event occurred. For a day after irradiation the patient stayed in a black-out ward without TV. Follow-up visits for wound dressing were scheduled every 3 to 7 days for the next 3 months. During follow-up, we used only systemic antibiotics and antihistamines as needed. Complete clinical resolution of the lesion was achieved by 3 months, and histologically confirmed with biopsy (Figure is not included). Currently, 24 months after PDT, the patient remains disease free with only cicatricial change of skin and no clinical signs of recurrence or metastasis (Fig. 1B). No photosensitivity reaction was reported.

The first photosensitizer, Photofrin has several disadvantages, particularly prolonged patient photosensitivity3. Systemic PDT with porfimer sodium for invasive SCC responds less well, with recurrence rate of up to 50% within 6 months4. Radachlorin®, an aqueous solution of three chlorines, including sodium salt of chlorine e6 (80%), sodium salt of purpurin 5 (15%), and sodium salt of chlorine p6 (5%), has a strong absorption peak at 662 nm, giving better depth penetration of light in tissue than the earlier photosensitizers such as porfimer sodium or 5-amino-levulinic acid5. Most importantly, it has a lower propensity to cause prolonged photosensitivity compared with the first-generation photosensitizers5,6. Intracellular fluorescence of this agent decreased slowly after 4 hours and the main part (98%) excreted from the organism in the first 24 hours5.

Although there are several studies of treatment of SCC of head and neck with chlorine PDT in otorhinolaryngological field7, there has not been any case in Korean dermatologic literature. This case showed that systemic PDT with chlorine could be an appropriate clinical selection in the treatment of elderly cutaneous SCC patients unable to receive surgery.