Chief: Adj A/Prof Chong Wei Sheng
The Photodermatology Unit attends to patients with photodermatoses or "sun allergy". Patients are evaluated based on their medical history, physical examination, phototesting and laboratory investigations. Dermatological conditions treated with various phototherapy or "light therapy" modalities include psoriasis, mycosis fungoides, vitiligo, atopic dermatitis, pityriasis lichenoides, eczema of the hands and feet, morphoea, uraemic pruritus, acne and skin cancer.
The Phototherapy division of the Photodermatology Unit provides the following phototherapeutic modalities :
• Narrowband UVB phototherapy
• UVA/Narrowband UVB combined phototherapy
• Systemic PUVA photochemotherapy
• Bath PUVA photochemotherapy
• Soak PUVA photochemotherapy
• Paint PUVA phototherapy
• UVA1 phototherapy
• Excimer lamp targeted phototherapy
• MultiClear targeted phototherapy
• Levia targeted phototherapy
• Photodynamic therapy
• Omnilux Blue phototherapy
The Photodiagnostic division of the Photodermatology Unit provides the following diagnostic methods:
• Photoprovocation testing
• Photopatch testing
• Systemic Drug Photochallenge
In phototherapy and photochemotherapy, both UVA and UVB may be used in combination with oral medications such as Acitretin (a retinoid or Vitamin A medication) and Methotrexate. Combination treatments increase the effectiveness in clearing psoriasis. ReNBUVB refers to the combined use of Acitretin and narrowband UVB phototherapy. Similarly, RePUVA is the combination therapy of Acitretin and PUVA photochemotherapy. These 2 combination modalities are very effective for the treatment of generalised and severe plaque psoriasis. They are generally recommended for those who fail to respond to NBUVB and PUVA alone. Acitretin enhances the therapeutic effects of NBUVB and PUVA and reduces the number of phototherapy treatment sessions and the cumulative UV doses.
Photodynamic therapy (PDT) involves the use of a photosensitiser and an activating light source in the treatment of skin diseases such as skin cancer. It was only with the development of topical PDT that its use in dermatology dramatically increased. In topical PDT, ALA (aminolaevulinic acid) or methylALA is applied onto the target skin lesion. This is taken up by the abnormal cells and converted to protoporphyrin IX via the haem biosynthesis pathway present within the cells. Protoporphyrin IX is a potent photosensitiser. It is activated by irradiation with an appropriate light source such as red light, resulting in generation of reactive oxygen species and damage to the target tissue. This treatment has been shown to be effective in skin diseases such as actinic keratosis, Bowen disease, superficial and nodular basal cell carcinoma. It has also been used in other dermatological diseases such as mycosis fungoides, viral wart, extramammary Paget disease, acne and keloid.
At NSC, we utilise the methylALA-Aktilite PDT system. This system is used commonly in Europe and Australia and we are the first institution in Asia to offer this treatment. It is a safe procedure with the main side effects of pain during the irradiation and possible redness and crusting, lasting up to a week after treatment. The procedure is simple. Topical methylALA or Metvix cream is applied to the lesion and left under occlusion for 3 hours. This is followed by irradiation with the Aktilite lamp (red light source) for about 8 min. Usually, 2 treatments a week apart are needed to treat actinic keratosis, Bowens disease and basal cell carcinoma. The advantage of this treatment is that it is a simple, non-invasive treatment with excellent cosmetic outcome and offers a good alternative treatment to traditional surgery. While it does not replace surgery in the treatment of Bowen disease and basal cell carcinoma, it offers an alternative to patients who are unsuitable or not keen on surgery and is a good option for treatment of lesions on difficult sites such as the face and ear or when a good cosmetic outcome is of great concern.
Excimer Lamp Targeted Phototherapy
From 1 September 2009, the National Skin Centre became the first healthcare institution in Singapore to offer the state-of-the art VTRAC excimer lamp phototherapy service to patients.
The excimer lamp source emits UVB light at a wavelength of 308 nm. This has been proven to be effective for a number of skin conditions, in particular psoriasis and vitiligo. It has been shown to clear psoriasis plaques faster with fewer treatments as compared to using NBUVB, and it is effective for vitiligo with repigmentation noted within weeks of treatment. The excimer lamp, which allows for targeted treatment of affected areas, complements the existing wide range of phototherapy devices already available at NSC. These devices include the NBUVB and UVA full-body cabins, MultiClear system and the localised hand and feet PUVA systems.
Levia Targeted Phototherapy
This simple-to-use targeted phototherapy system emits NBUVB wavelength to treat many skin diseases, similar to the Excimer Lamp Phototherapy System. However, it is a much smaller machine, extremely portable , and the handpiece is light-weight and shaped like a hair dryer, thus providing better ergonomics to the user. Also, it has the LiteBrush attachment specifically used to treat scalp psoriasis and eczema besides having the LiteSpot attachment (used for treating non-scalp lesions). This attachment consists of multiple bristles that come into direct contact with the scalp skin to allow direct UV irradiation onto the skin, unlike the usual targeted phototherapy systems which do not bear bristles on their probes. This light-weight system can be used both at the doctor's clinic and at home. Patients who require targeted phototherapy and find it inconvenient to come to NSC for phototherapy can treat themselves using this system at the comfort of their own home., providing more satisfaction, convenience and autonomy to these patients who would feel more in charge of their own skin conditions. This service will commence in January 2016.
Omnilux Blue Phototherapy
This system emits blue light at a wavelength of 415 nm, targeting the bacteria in the hair follicles called Propionibacterium acnes and killing them, thereby resulting in improvement of acne lesions. This system is used in the treatment of mild to moderate acne. Each treatment session lasts 20 min and the patient needs to come twice per week for the blue light therapy. It will benefit many patients with acne vulgaris where oral treatment is contraindicated or intolerant, or when one is not keen on oral therapy. This service will commence in the first quarter of 2016.