Rash morphology and histology as prognostic indicators
Dr. Walsh was the lead investigator in a study that identified four distinct patterns of skin involvement in patients with DRESS. The most common type of rash in this single-center retrospective study of 27 consecutive patients was an urticated papular exanthem, present in 13 of the 27 patients. An erythema multiforme-like reaction was present in 8, exfoliative erythroderma in 3, and a morbilliform erythema in 3 others. The worst prognosis was in the subgroup with an erythema multiforme-like rash.
All 27 patients had hepatic involvement, which was severe in 9 cases. Six of the 9 with severe liver impairment had an erythema multiforme-like rash, compared with just 2 of the 18 with mild or moderate liver involvement; thus, an erythema multiforme-like skin eruption was associated with a fivefold increased likelihood of severe hepatic involvement.
“It is a clinical sign that we take seriously at presentation if atypical target lesions are present,” the dermatologist said.
Separately, Taiwanese investigators compared clinical and histopathologic features in a study of 32 patients with DRESS and 17 with maculopapular exanthem. Interface vacuolization, which was present in 29 of the 32 patients with DRESS, was far more prominent than in the comparator group. Moreover, severe dyskeratosis was significantly associated with more severe liver impairment in the DRESS group.
HLA testing
Testing for HLA haplotypes associated with severe drug reactions has a useful role as a screening tool prior to prescribing selected high-risk drugs, Dr. Walsh said. For example, it’s known that 6.8% of individuals of European ancestry carry HLA-A*32:01, an allele that was strongly associated with an increased rate of vancomycin-associated DRESS in a case-control study at Vanderbilt University, Nashville, Tenn. Indeed, 19 of 23 individuals with vancomycin-associated DRESS were HLA-A*32:01 positive, compared with none of 46 vancomycin-tolerant controls. Nineteen percent of HLA-A*32:01-positive patients developed DRESS during treatment with vancomycin, and the drug reaction occurred within 4 weeks.
The investigators noted that testing for HLA-A*32:01 is also useful in DRESS occurring in patients on vancomycin and multiple other drugs because the test’s high negative predictive value may safely allow continued therapy with this potent antibiotic for Gram-positive infections.
A DRESS prognostic scoring system
Japanese researchers have developed a scoring system for DRESS for use in monitoring severity of the drug reaction, predicting prognosis, and estimating the risk of developing cytomegalovirus disease and its potentially fatal complications. The scoring system incorporates patient factors, including age, duration of drug exposure after symptom onset; rash characteristics, such as percentage of body surface area involved and presence or absence of erythroderma; appetite loss; and laboratory values.
“It yields a prognostic score that can be used to determine treatment choices, such as immediate intervention with anti-CMV agents. It’s a very useful tool,” Dr. Walsh said.
She reported having no financial conflicts regarding her presentation.