Erythema
Frequently asked questions
- What is erythema?
- How much radiation dose to the skin is necessary for the production of erythema?
- Will multiple interventional procedures increase the risk of erythema?
- How soon one can expect to see radiation-induced erythema in the clinical practice of radiological interventional procedures?
- Should all patients undergoing interventional procedure be expected to have skin injury and asked to report back for a check-up?
- What approach can help to diagnose radiation-induced erythema after a radiological procedure?
- How to treat erythema?
- Are some patients at greater risk for radiation injury than others?
1. What is erythema?
Erythema means ‘reddening’ of the skin due to inflammatory or immunologic processes. Irradiation leads to accumulation of lymphocytes in the layers of the skin caused by the effects of cell death. There can be many reasons for the occurrence of erythema: exposure to heat, insect bites, infections, allergy, non-ionizing radiation (sunlight, UV) and ionizing radiation (X-ray, nuclear radiation). Of these, erythema induced by ionizing radiation is the least seen in practice and thus many physicians and dermatologists lack experience in diagnosing radiation induced erythema, although it has been well known since the late 1890s, soon after the discovery of X rays and radioactivity.
2. How much radiation dose to the skin is necessary for the production of erythema?
Erythema may appear within a few hours after acute exposure to radiation with a skin dose of about 2 to 3 gray (Gy) for radiation energies encountered in X ray machines used for interventional procedures, whereas 6 to 8 Gy with 200 kV radiation used in radiation therapy are required for erythema to occur. Radiation of higher energies requires larger doses to produce the same degree of erythema since in these cases the maximum dose is received below the skin. Since erythema falls into the category of effects called deterministic effects that have a threshold, theskin dose of 2 Gy is considered the threshold dose. In actual practice the skin dose in interventional procedures varies over the body, and it is the dose to the area with highest skin dose (peak skin dose – PSD) that determines whether erythema is expected to occur.
3. Will multiple interventional procedures increase the risk of erythema?
The general answer to this question is ‘yes’, as higher doses imply a higher risk or erythema.
However, ‘splitting’ the delivery a particular amount of ionizing radiation over multiple sessions can reduce effects of erythema. Radiation effects tend to be cumulative, with the possibility of repair in-between two consecutive exposures. If there is a time gap between two interventional procedures, repair processes enable the skin to tolerate higher radiation; the repair processes depend upon the time gap and the number of times the radiological procedure is repeated. There is a lack of direct information on this in relation to dose effects from X rays of diagnostic range. Information on skin repair is primarily available in relation to high energy radiation as used in radiotherapy. For example, with three fractions administered at 200 kV, the erythema dose is 11 Gy instead of the 6 - 8 Gy from a single dose of 200 kV. With 10 fractions, a total dose of 16.5 Gy is necessary, and with 30 fractions, a total dose of 26 Gy is required to induce the same effect. Repair of injury between fractions is responsible for these differences in the erythema dose. A single dose to reach skin necrosis is usually considered to be 25 Gy given in single procedure. These figures may not be valid in the case of X rays of diagnostic range, but the principle remains valid.
4. How soon after a radiological interventional procedure can one expect to see radiation-induced erythema?
In a few cases where doses are very high, erythema can be observed a few hours after irradiation. This timing makes the recognition of the possible link between the irradiation and skin symptoms easier, but this situation is rare.
In most cases [Wagner 2007] the delay is typically about two to three weeks before symptoms emerge, and three to four weeks before is the symptoms are sufficiently irritating for the patient to see a doctor. Thus, if not informed in advance, physicians and patients do not usually associate the skin reaction with the radiological procedure. For further information on different stages of erythema, please click here
5. Should all patients undergoing interventional procedures be expected to have skin injuries and be asked to report back for a check-up?
No. A systematic ‘follow-up’ check-up of all patients undergoing an interventional radiology procedure is not necessary. However, it is of utmost importance that all patients undergoing such procedures be aware of the possibility of skin symptoms, so that they can report on time of any skin symptom occurring in the relevant areas. This will help to detect patients with higher radiosensitivity (ataxia telangiectasia). Moreover, the awareness about the possibility of erythema on the part of doctors performing radiological procedures and also among dermatologists is essential. An understanding of threshold dose and information about the dose delivered to the patient can be helpful in avoiding unnecessary follow-up or concern. The patient should be advised about the areas on the skin of the back (in cardiac interventions) where erythema might develop. The patient should be asked to examine himself or herself until about 2 to 3 weeks after the procedure for any skin changes in those areas. Some facilities place a follow-up call to the patient during this time to query about any skin irritation and this is found to be effective in ensuring that a patient who develops skin irritation does not seek medical help at a place where there may be a chance of missing the correct diagnosis.
6. What approach can help to diagnose radiation-induced erythema after a radiological procedure?
In clinical practice, the diagnosis of radiation induced erythema may be either extremely difficult (as has been the case in many patients in the past) or very easy, if the appropriate approach is followed.
The worst situation may occur when the patient has not been informed at all about the possible skin effects, and when no follow-up, whatever its type, has been planned. In such a situation, the patient leaves the facility with no knowledge about the potential skin effects. If an effect develops, the patient is not likely to associate it with the procedure, which was performed previously. If the patient seeks medical help for the erythema, the physician might not realize that the angiographic procedure could have caused the effect and will look for other diagnoses, all of which would be incorrect. Care will be uncertain. The literature reports on many cases for which weeks have been lost in trying to put a name on the strange and unusual skin lesions presented by the patient, with a succession of ineffective therapies. Everything should be done to avoid such situations. Last but not least, in those cases, the facility will have no feedback that this has occurred, leaving a false sense of security about the safety of future procedures.
On the other hand, the diagnosis becomes much easier if the patient has been informed about the possibility of skin symptoms (reddening, itchy lesion …) in the relevant area: in such a situation, he can report immediately to his interventionalist, who will easily identify the link with the radiological procedure. If the patient seeks the advice of a dermatologist or of any physician, he will be able to mention his recent radiological procedure as possibly responsible for such a skin lesion, and this will obviously help the physician to identify the direct link between the irradiation exposure and the skin erythema.
This being known, the main erythematous phases are rather typical, and there are very few other diseases able to mimic such lesions (essentially since they draw a precise outline of the exposed areas). Click For further information
7. How to treat erythema?
Local management of erythema remains a matter of discussion, controversies and studies.
The first (transient) early phase usually does not require any treatment, and frequently subsides before any therapy can be started.
The second erythema phase (if correctly recognized) usually triggers some prescriptions. One of the most popular therapies is aloe vera, given in lotion or ointment. Although it has not been proven very effective in radiotherapy induced erythema, and not superior to other ointments or creams through several trials, it remains largely prescribed.
Biafin cream is also largely prescribed, particularly by the radiotherapy community. However, here again, there is no randomized trial supporting its use, which is actually questioned by some authors.
Trolamin has been tested in several trials; there was no advantage for its use in a series of 547 patients irradiated for cancers of the head and neck [Elliott, JSO 2006]. One trial showed a superiority over Biafin, but another showed an inferiority over Calendula.
Calendula Officinalis is one of the rare treatments of early phase skin reactions for which a clear advantage (versus Trolamin) has been demonstrated in a randomized trial: 254 patients irradiated for a breast cancer were randomly assigned either to Calendula local therapy (126 Cases) or to Trolamin (128). The incidence of grade 2 radiodermatitis was less with Calendula (41 %) than with Trolamin (63 %) ( p<0.001) [Pommier, JCO 2004].
Local steroids (ointments) also remain largely prescribed [Bostrom, Radiother.Oncol. 2001], but a randomized trial [Schmuth, Br.J. Dermatol., 2002] has not shown any interest in using this therapy as a prevention of radiation-induced erythema in radiotherapy. They may however help reduce the inflammatory reaction.
Hyaluronic acid could be an interesting candidate for the treatment of early radiation-induced skin reactions; a double-blind, randomized trial [Liguori, Radiother.Oncol., 1997] has shown that the prophylactic use of a cream with hyaluronic acid was able to reduce the incidence of high-grade radiodermatitis compared to a placebo.
When the level of injury reaches moist desquamation, eosin and anti-pain therapies are usually necessary, combined with antibiotics and steroids in selected cases that require them.
Management of necrosis exceeds the frame of this document. It has to be known that the management of large radiation-induced necroses is usually difficult and should be discussed within experienced teams.
Large excisions are required of the necrotic tissue and of the surrounding tissue that is ‘doomed to die’. Such excisions are increasingly guided by complementary explorations such as MRI. Reconstruction may use autologous skin grafts, but may necessitate in some cases much more sophisticated approaches (such as the graft of artificial dermis in an intermediate phase, musculo-cutaneous rotational or ‘free’ flaps, epiploïc flaps etc. …).
8. Are some patients at greater risk for radiation injury than others?
Some rare health conditions render patients highly sensitive to radiation, e.g. patients with the homozygous form of the ataxia telangiectasia gene, or patients with Fanconi disease. Diseases such as collagen vascular diseases and diabetes mellitus are also suspected in rendering patients more susceptible to injury.
Diabetes compromises the vascular supply and this leads to a greater risk for long-term complications.
The reasons why some patients with collagen vascular disease are more sensitive to radiation are unknown. Moreover, having the disease does not systematically predispose patients to heightened sensitivity. Only a few patients with collagen vascular disease have been identified to have greater radiation sensitivity. Whether or not the skin type of an individual is correlated with sensitivity for radiation induced erythema is still a matter of discussion.
References
- Wagner, L.K., Radiation injury is a potentially serious complication to fluoroscopically-guided complex interventions, Biomed. Imaging Interv. J.3 2 (2007) e22.
- Elliott, E.A., Wright, J.R., Swann, R.S., Nguyen-Tân, F., Takita, C., Bucci, M.K., Garden, A.S., Kim, H., Hug, E.B., Ryu, J., Greenberg, M., Saxton, J.P., Ang, K., Berk, L., Phase III Trial of an Emulsion Containing Trolamine for the Prevention of Radiation Dermatitis in Patients With Advanced Squamous Cell Carcinoma of the Head and Neck: Results of Radiation Therapy Oncology Group Trial 99-13, JCO 24 13 (May 2006) 2092-2097.
- Pommier, P., Gomez, F., Sunyach, M.P., D'Hombres, A., Carrie, C., Montbarbon, X., Phase III Randomized Trial of Calendula Officinalis Compared With Trolamine for the Prevention of Acute Dermatitis During Irradiation for Breast Cancer, JCO 22 8 (Apr. 2004) 1447–1453.
- Boström, A., Lindman, H., Swartling, C., Berne, B., Bergh, J., Potent corticosteroid cream (mometasone furoate) significantly reduces acute radiation dermatitis: results from a double-blind, randomized study, Radiother. Oncol. 59 3 (Jun. 2001) 257-265.
- Schmuth, M., Wimmer, M.A., Hofer, S., Sztankay, A., Weinlich, G., Linder, D.M., Elias, P.M., Fritsch, P.O., Fritsch, E., Topical corticosteroid therapy for acute radiation dermatitis: a prospective, randomized, double-blind study, Br. J. Dermatol. 146 6 (Jun. 2002) 983-991.
- Liguori, V., Guillemin, C., Pesce, G.F., Mirimanoff, R.O., Bernier, J., Double-blind, randomized clinical study comparing hyaluronic acid cream to placebo in patients treated with radiotherapy, Radiother. Oncol. 42 2 (Feb. 1997) 155-161.