Drug-induced exanthems: correlation of allergy testing with histologic diagnosis.
BACKGROUND
Skin biopsies are commonly performed to confirm drug-induced exanthem (DIE). However, the relevance of histologic examination in discriminating between DIE and non-DIE (NDIE) is controversial.


OBJECTIVE
A retrospective analysis was performed to evaluate the reliability of histologic diagnosis of DIE.


METHODS
In all, 91 patients with a skin biopsy specimen of an acute exanthem temporally related to a single identifiable drug underwent complete allergy testing. Their biopsy specimens were retrospectively re-evaluated by 2 dermatopathologists blinded to the original reports to test for discrimination between DIE versus NDIE.


RESULTS
In 35 patients, non-IgE-mediated drug allergy was confirmed by allergy testing, whereas in 56 patients drug hypersensitivity could be excluded. Sensitivity of pathology reports for diagnosis of DIE reached 62.9% with a positive predictive value of 40.7%. Specificity was 41.1% with a negative predictive value of 69.7%. No significant difference in tissue eosinophilia was detected between DIE and NDIE.


CONCLUSIONS
This was a retrospective study.


CONCLUSIONS
Dermatopathologic evaluation of skin biopsy specimens is of limited use in differentiating between DIE and NDIE. All efforts should be made to subject these patients to thorough allergy testing for definitely confirming or ruling out drug hypersensitivity.
Department of Dermatology and Allergy, University Hospital of Göttingen, Göttingen, Germany. Electronic address: cseitz@med.uni-goettingen.de.
Cornelia S
CS
Seitz
Dermatopathology Laboratory, Lübeck, Germany.
Christian
C
Rose
Department of Dermatology and Allergy, University Hospital of Würzburg, Würzburg, Germany.
Andreas
A
Kerstan
Department of Dermatology and Allergy, University Hospital of Würzburg, Würzburg, Germany.
Axel
A
Trautmann
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003875:Drug Eruptions / Q000473:pathology*; D005076:Exanthema / Q000139:chemically induced* / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012882:Skin Tests; D055815:Young Adult
DIE; LTT; NDIE; challenge testing; drug allergy; drug eruption; drug rash; drug reaction; drug-induced exanthem; eosinophils; exanthem; histopathology; lymphocyte transformation test; non-drug-induced exanthem; provocation testing; skin testing