Clinical Diagnosis More Accurate Than Skin Biopsy in Inherited EB Patients, Study Reports
A provisional diagnosis based on clinical information is more accurate than imaging of skin biopsies in newborns and infants with inherited epidermolysis bullosa (EB), according to a new study.
The research, “A retrospective cohort study evaluating the accuracy of clinical diagnosis compared to immunofluorescence and electron microscopy in children with inherited epidermolysis bullosa,” was published in the British Journal of Dermatology.
Although guidelines recommend skin biopsy as a first-line option to assess EB diagnosis, the accuracy and short turnaround time of genetic testing warrants consideration about how to address potential EB cases in infants. Particularly, skin biopsy offers a limited potential for milder (and most common) subtypes of EB — dominant dystrophic EB (DDEB) and EB simplex (EBS).
The team from Australia and the U.K. intended to compare the accuracy of clinical provisional diagnosis to that of the imaging approaches electron microscopy (EM) and immunofluorescence mapping (IPM) in EB cases confirmed through molecular diagnosis. Also, the investigators aimed to determine if specific clinical features were more common in distinct subtypes of genetic EB.
The 170 patients attended EB multidisciplinary clinics at the Sydney Children’s Hospital and The Royal Children’s Hospital Melbourne between 1986-2017. Clinical provisional diagnosis was obtained from clinical notes taken prior to diagnostic testing by any method.
Sixty-five patients underwent genetic testing, 40 of whom also had IFM and 36 had EM after skin biopsy. This group included 35 newborns (mean age 7.9 days) and 30 infants (mean age 2.9 years).
The results revealed a 75% accuracy with both IFM and EM, and an 81.5% accuracy with clinical provisional diagnosis. This higher accuracy with clinical provisional diagnosis was seen in both newborns and infants.
Small white spots known as milia were more frequent in patients with DDEB (17 in 20) or recessive DEB (RDEB, eight in 10). Mucosal involvement (nine cases, 90%), nail dystrophy (all 10 patients), and atrophic, or shrinking, scarring (nine patients) were more common in RDEB. Atrophic scarring also was common in DDEB, found in 15 patients (75%).
Generalized blisters were observed in all 10 RDEB patients, while acral blisters (on the body’s extremities) were found in 22 of 25 EBS cases. In turn, all eight patients with junctional EB (JEB) had granulation tissue, which refers to connective tissue formed during normal wound healing.
Twelve children (18.5 %) required more than one biopsy, which the team attributed to a past requirement in Australia for a diagnostic biopsy prior to having access to the National EB Dressing Scheme.
As for age groups, nail dystrophy was more frequent in infants (20 cases, 66.7%) than in newborns (nine cases, 25.7%). Similar differences were found in milia (50% vs. 11.4%) and atrophic scarring (43.3% vs. 2 5.7%). In contrast, mucosal lesions were more common in newborns (54.3%) than in infants (20.7%).
“In conclusion, rapid molecular diagnostic testing guided by clinical diagnosis can provide the precise diagnosis of EB in many cases, negating the need for routine skin biopsy,” the scientists wrote.
Cautioning that the sample size is small, the team suggested replacing skin biopsy with clinical diagnosis-guided genetic testing in countries where molecular diagnostic testing is available and when specific clinical features are observed.
However, skin biopsies remain important in cases with unclear or not-yet-established EB features, the investigators noted.