A 30-year-old woman developed chronic radiodermatitis and five squamous cell carcinomas within 7 years following a 16-year period of repeated grenz irradiations given to her psoriasis. The estimated cumulative dose of grenz radiation was approximately 3,000 rads (r) to each treated area.This case, illustrating a rather underestimated carcinogenic potential of grenz rays, is interpreted in light of the available literaure on the subject. The technical bases of grenz ray therapy are also briefly reviewed.KEY WORDS: grenz rays, skin cancer, squamous cell carcinoma, radiation dermatitis
INTRODUCTIONGrenz rays have been widely and successfully used for the past 60 years to treat many inflammatory skin diseases, including psoriasis vulgaris [ 1,2]. The major controversy surrounding the use of grenz rays relates not to the therapeutic efficacy of this modality but to its safety. It was long believed that this form of therapy was free of the hazards of hard X-radiation, especially of its carcinogenic effects. Considering the effects on human skin, acute and chronic radiodermatitis related to grenz rays were recognized soon after their discovery [3-51. However, there are only a few reports in the medical literature of well-documented cases of skin neoplasms arising as a consequence of this softest variant of X-rays [5-9,ll-141. In the present paper, we describe yet another patient who, after 16 years of repeated grenz irradiations for psoriasis, developed multiple squamous cell carcinomas of the skin.
REPORT OF A CASEA 30-year-old white woman had psoriasis vulgaris since the age of 7 years. Most of the plaques were located on the extremities, especially around the knees and elbows, but single lesions continued to periodically appear on the trunk as well. Her scalp was never involved. Since the time of her original diagnosis of psoriasis until about 3 years prior to her first visit to our department in October 1983 (a time interval of 20 years), she had been treated by her dermatologist with grenz rays. Treatments were given periodically at times of exacerbation of her psoriasis. The grenz radiation was generated at 8 or 10 kV and 10 mA with a focus-to-skin distance of 20 cm. The half-value layer was 0.02-0.03 mm Al. The usual full dose of 200 r was given at 24-week intervals to any single location on the lower and upper extremities. The patient received three exposures per area in 1961, six in 1962, only one in 1963, and none further until 1970. Other treatment, at that time, consisted of various topical and injectable corticosteroids and of several courses of oral methotrexate. Between 1970 and 1974, she received more grenz radiation with an average total dose to a single area of 100 r a year. From the information provided by the treating physician, it can be assumed that the accumulated dose delivered to a single skin area during a period of 20 years reached at least 3,000 r, with slight variations between some areas depending on the degree of involvement. The patient had no recollection of being treated with medica...
