Diagnostic value of immunohistochemistry on formalin-fixed, paraffin-embedded skin biopsy specimens for bullous pemphigoid.
BACKGROUND
Direct immunofluorescence microscopy (DIF) studies constitute the gold standard for diagnosis of bullous pemphigoid (BP) but depend on the availability of specialized laboratories and often on an additional skin biopsy specimen.


OBJECTIVE
To assess the value of immunohistochemical analyses (IHCA) in the diagnosis of BP using formalin-fixed, paraffin-embedded skin biopsy specimens as an alternative to DIF; and to study the correlation between the results of IHCA and the presence of histological subepidermal blister formation and of circulating autoantibodies by indirect immunofluorescence studies using split skin or by enzyme-linked immunosorbent assays.


METHODS
We included all patients newly diagnosed with BP evaluated between 2008 and 2010. There were 51 consecutive skin biopsy specimens obtained from 38 patients with BP with positive DIF.


RESULTS
By IHCA, deposits of immunoreactants were found in 45% of all tested cases. Deposits of C3d, IgG, IgM, IgE and IgA were found in 37%, 23%, 2%, 0% and 0% of cases, respectively. Deposits of C3d and/or IgG were found in 79% of the 24 cases with a blister and in 83% of the 12 cases with subepidermal blistering and positive immunoserological analyses, respectively.


CONCLUSIONS
In contrast to previous studies, our findings in an unselected patient cohort indicate that IHCA are not sufficiently sensitive to replace DIF studies for confirming the diagnosis of BP. IHCA sensitivity significantly increases in the presence of histological blistering and/or of circulating autoantibodies. IHCA represents a potential rescue diagnostic technique only if specialized laboratories and/or a second biopsy specimen for DIF are unavailable.
Department of Dermatology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.
S
S
Glauser
Department of Dermatology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.
M
M
Rutz
Department of Dermatology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.|Centro Studi GISED, Bergamo, Italy.
S
S
Cazzaniga
Department of Dermatology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.
I
I
Hegyi
Department of Dermatology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland. luca.borradori@insel.ch.
L
L
Borradori
Department of Dermatology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland. helmut.beltraminelli@insel.ch.
H
H
Beltraminelli
D000368:Aged; D000369:Aged, 80 and over; D001323:Autoantibodies / Q000378:metabolism; D005260:Female; D019085:Fluorescent Antibody Technique, Direct; D006801:Humans; D007136:Immunoglobulins / Q000378:metabolism; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D010391:Pemphigoid, Bullous / Q000175:diagnosis* / Q000276:immunology; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
D001323:Autoantibodies; D007136:Immunoglobulins