White petrolatum (Ph. Eur.) is virtually non-sensitizing. Analysis of IVDK data on 80 000 patients tested between 1992 and 2004 and short discussion of identification and designation of allergens.
Sporadic cases of contact allergy to white petrolatum, which is used as a vehicle in patch test preparations, have been reported. The quantitative relevance of the phenomenon remains yet to be elucidated.


METHODS
Retrospective analysis of patch test data of the Information Network of Departments of Dermatology (IVDK, http://www.ivdk.org) between 1992 and 2004.


RESULTS
Analysis of 79 365 patients patch tested with pure petrolatum yielded 27 '+' (0.03%) and 2 '+++' (0.003%) reactions. The majority of non-negative reactions (0.3%) was interpreted as doubtful (235) or mild irritant (32). The negative reaction index (RI) (-0.8), and the high positivity ratio (PR) (93%) especially a lack of concordance with patch test preparations containing > or=99% petrolatum indicate that many of the 'positive' (+) reactions have to be considered as irritant. There were 2 '+++' reactions. In 1 case, an 'angry back reaction' was confirmed. The other case is probably a reading or documentation error, as the majority of patch test reactions to preparations containing petrolatum remained negative in this case also.


CONCLUSIONS
True allergic patch test reactions to white petrolatum are extremely rare and probably due to an individually increased susceptibility to allergens and/or irritants. This is in agreement with considering petrolatum as a non-sensitizer.
Schnuch
Axel
A
Zentrale des IVDK, Institut an der Universität Göttingen, Göttingen, Germany. aschnuch@med.uni-goettingen.de
Lessmann
Holger
H
Geier
Johannes
J
Uter
Wolfgang
W
D000485:Allergens; D003627:Data Interpretation, Statistical; D017449:Dermatitis, Allergic Contact / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology* / Q000276:immunology; D005189:False Positive Reactions; D005260:Female; D005858:Germany / Q000453:epidemiology; D006801:Humans; D008297:Male; D010328:Patch Tests; D010577:Petrolatum / Q000009:adverse effects*
D000485:Allergens; D010577:Petrolatum