PD13 Refractory inflammatory dermatoses: 17 years’ British grenz ray experience

Abstract Grenz ray therapy is a type of ultrasoft X-ray therapy used since 1923. In our centre, treatment is usually weekly, with dose per treatment varying according to indication and other factors (such as hair thickness if treating the scalp). Treatment courses are usually fractionated over six to eight treatments. Six cones of different diameter from 1 cm to 9 cm are used to deliver grenz rays. After a satisfactory response to a test treatment dose (one small area treated initially), therapy is guided by centre experience, with monthly onsite medical physics safety checks. Dosing examples include 4–6 Gy for hand or foot eczema or psoriasis, 3–6 Gy for scalp psoriasis, 3–7 Gy for nail dystrophy and 3–6 Gy for palmoplantar pustulosis. Lower doses are used when treatment includes mucosal sites, such as just 0.5 Gy to treat the vulva or for pruritus ani. Some conditions such as disseminated superficial actinic porokeratosis (DSAP) are more often associated with erythema from treatment than other conditions, so often modest doses (e.g. 3 Gy) are needed at each treatment. We characterized our real-world experience of treating mainly inflammatory dermatoses with grenz ray therapy over the past 17 years. This was by review of a treatment database and patients’ notes. Some patients were treated at more than one site and had more than one course of treatment. Scalp psoriasis, the single most frequent indication (107 patients), cleared in 23, markedly improved in 46, slightly improved in 32 and did not change in six. Hand or foot eczema and psoriasis (sometimes mixed) was treated in 26 patients, ear psoriasis in 31, nail psoriasis in 31, acrodermatitis of Hallopeau in five; Darier disease in five and DSAP in three. Our experience supports the use of grenz ray therapy for some otherwise recalcitrant dermatoses such as scalp psoriasis. However, it is also used for some other disorders that can be difficult to treat, including other localized forms of psoriasis, acrodermatitis of Hallopeau, Darier disease and DSAP. In an era of advanced immunomodulation, recalcitrant dermatoses may benefit from alternative, cheap, patient-friendly, skin-directed (not systemic) treatments.