Photopatch testing in Bogota (Colombia): 2011-2013

Shedding a light on the importance of photopatch testing: A 12-year experience in a dermatology unit

BACKGROUND

Photopatch testing has been standardized for diagnosing photoallergic contact dermatitis but is still infrequently used.

OBJECTIVES

To characterize photopatch test (PPT) results and their clinical relevance.

METHODS

We collected retrospective data from patients photopatch tested in our Dermatology Unit (2010-2021), using the European PPT 'baseline' series, other allergens, and patient's own products, when appropriate.

RESULTS

Out of 223 patients, 75 patients (33.6%) were reactive with 124 positive PPT reactions, considered relevant in 56/223 patients (25.1%) and in 72/124 reactions (58.1%). Most reactions were caused by topical drugs (n = 33; 45.8%), such as ketoprofen or promethazine, and 7 (9.8%) by systemic drugs, such as hydrochlorothiazide and fenofibrate. 'Classical' ultraviolet filters were responsible for six positive PPT reactions whereas there was only three relevant PPT to the 'newer' UV filters. Patients' sunscreens/cosmetics or plant extracts caused 10 positive PPT each. Additional patch test reactions were observed, mostly to Tinosorb® M.

CONCLUSION

Contrary to the trend in ACD, most positive PPT reactions were caused by topical drugs, outweighing ultraviolet filters and cosmetics. We stress the low reactivity to the 'newer' UV filters included in the PPT series. PPT was occasionally positive in systemic drug photosensitivity, but overall PPT reactivity was low.

Contribution of phototesting in the diagnosis of photodermatoses: Retrospective study of 100 cases

BACKGROUND

Photodermatoses are sun-related inflammatory skin diseases. They usually require phototesting in diagnosis. However, fewer and fewer medical centers in France are equipped with photobiological equipment.

OBJECTIVES

The main purpose was to evaluate the relevance of phototesting in photodermatosis diagnosis. The second goal was to study the proportions of the different kinds of photodermatosis found in this particular study.

METHODS

This study was descriptive, retrospective, and mono-centric. It was based on 100 consecutive patients, who have been phototested in a French University Hospital from 2014 to 2018. Phototesting included determination of the minimal erythematous dose (MED), UVA and UVB phototests, and photopatch testing.

RESULTS

The use of phototesting led to 60% of photodermatosis diagnosis and formally eliminated the latter in 13% of the cases. The diagnosis remained undetermined in 27% of the cases. Nineteen cases of polymorphous light eruption (PLE), 14 cases of photocontact dermatitis (PCD), 10 cases of solar urticaria, 8 cases of photo-aggravated atopic eczema, 5 cases of chronic actinic dermatitis, and 2 cases of systemic photosensitization were diagnosed. The allergens involved in PCD were topical non-steroidal anti-inflammatory drug (NSAID) in 9 cases, sunscreens in 3 cases, and fragrance in 2 cases. The average amount of time between the first symptoms and actual phototesting was about 7,5 years.

CONCLUSION

This study confirms phototesting is truly useful. PLE was the most common form of photodermatosis, followed by PCD and solar urticaria. As photodermatosis could imply severe diseases sometimes requiring hospitalization, it is critical to maintain this expertise.

Photopatch testing in a tropical country, Thailand: 20 years' experience

BACKGROUND

Photoallergic contact dermatitis is one of the important parts of photodermatoses. The investigation of choice is photopatch testing. However, reports with photopatch test results from Asian countries are scarce. The objective of this study was to determine the prevalence of positive photopatch test reactions and to ascertain the common photoallergens among Thai patients during 1998-2018.

METHODS

We retrospectively reviewed the records of 339 patients who were clinically suspected of having photoallergic contact dermatitis and had undergone photopatch testing.

RESULTS

A total of 44 photoallergic contact reactions in 38 patients (11.2%) were found. The positive photoallergic reactions were mainly found with organic ultraviolet filters and fragrances.

CONCLUSIONS

Organic ultraviolet filter chemicals especially benzophenone-3 and fragrances were found to have a high prevalence of photoallergic contact reactions. Monitoring of the photoallergens employed in photopatch tests should be conducted periodically to provide the best patient care.

Drug and chemical induced photosensitivity from a clinical perspective

Drug photosensitivity is a relatively common occurrence and a range of mechanisms may be involved. Some of these mechanisms will be discussed, including the most common, that of drug phototoxicity. Different types of photosensitivity are addressed with respect to clinical presentation, mechanisms and additionally the contribution to our understanding through clinically directed investigations and regulatory requirements. Repeated controlled therapeutic use of drug phototoxicity, with psoralen-UVA (PUVA) photochemotherapy and photodynamic therapy (PDT) will also be discussed. Finally, the potential for drug-induced photocarcinogenesis will also be covered.