Frequency of sensitization to methyl aminolaevulinate after photodynamic therapy

Abstract

This study demonstrates a considerable risk of sensitization after Metvix-PDT. We suggest that the patients are interviewed to detect late or persistent local reactions after PDT. These reactions are often considered to be local infections but may represent allergic contact dermatitis, and therefore, patients should be offered patch testing with Metvix cream.

European guidelines for topical photodynamic therapy part 1: treatment delivery and current indications – actinic keratoses, Bowen’s disease, basal cell carcinoma

“…There is a risk of sensitization to MAL that might give an exaggerated response to patients receiving further PDT with the same drug formulation 100–103 …”

“…There is a risk of sensitization to MAL that might give an exaggerated response to patients receiving further PDT with the same drug formulation. [100][101][102][103] Two case reports of melanoma within the field of previous PDT and of SCC developing following PDT (supplemented by topical 5-fluorouracil) for penile intraepithelial neoplasia could represent evidence of progression, but the melanomas may well have arisen coincidentally, and the SCC development may be due to incomplete response of the PIN to two therapy modalities. [104][105][106]…”

Adverse effects of topical photodynamic therapy

“…Interestingly, there were no reactions to the placebo cream, suggesting that in these index cases, it was MAL itself, and not an excipient, as the allergen. Four of the seven patients (57%) were considered to have clinically relevant positive patch tests to Metvix (117). Thus, these more recent data do indicate that the risk of sensitization to Metvix PDT is significant and that patch testing should be considered.…”

Consensus recommendations for the treatment of basal cell carcinomas in Gorlin syndrome with topical methylaminolaevulinate‐photodynamic therapy

“…Although it was suggested that MAL‐PDT may be continued with the use of prophylactic oral antihistamines, experts recommended to stop the treatment if the sensitization test is positive. A controlled study including 20 patients with at least 5 prior exposures to MAL‐PDT showed that 7 patients (35%) were sensitized, and 4 of these patients had relevantly positive patch tests . In the control group, 1 of 60 patients (1.7%) became sensitized after a single exposure .…”

“…A controlled study including 20 patients with at least 5 prior exposures to MAL‐PDT showed that 7 patients (35%) were sensitized, and 4 of these patients had relevantly positive patch tests . In the control group, 1 of 60 patients (1.7%) became sensitized after a single exposure . In a case study of 9 patients who developed allergic dermatitis to MAL, the average risk of contact allergy was 1% after an average of 7 treatments, and there was no negative impact on treatment results .…”