Background Evaluation of a potential immunobullous disorder typically requires two pieces of tissue obtained by skin biopsy: one placed in formalin for conventional microscopy and a second placed in a different transport medium suitable for direct immunofluorescence (DIF) testing. Clinical practice in this area is not standardized, with dermatologists either obtaining two biopsies or dividing (pre-bisecting) a single biopsy. Some DIF specimens are technically inadequate for interpretation of subepidermal imunobullous disorders because the basement membrane zone is not intact, but it is unknown whether pre-bisecting the tissue increases the risk of compromising the specimen. Objective To investigate whether technically inadequate DIF specimens are associated with pre-bisection.
Methods DIF specimens were consecutively sampled from a single referral center and identified as whole (non-bisected) biopsy specimens or pre-bisected biopsy specimens. The proportion of inadequate specimens was calculated for both groups.
Results A total of 3450 specimens were included. The percentage of inadequate specimens was 5.072% (153/3016) for whole (non-bisected) specimens and 5.299% for pre-bisected specimens. This difference was not significant (chi square, p = 0.84). The study was sufficiently powered to detect a relative risk of 1.685.
Conclusions Pre-bisection of a single skin biopsy does not significantly increase the risk of a technically inadequate specimen for direct immunofluorescence testing.
- bullous pemphigoid