Background and design: The fibrillar immunofluorescent pattern of IgA deposition in dermatitis herpetiformis is considered by most authorities to be a variant of the granular IgA pattern. It has been hypothesized that the fibrillar vs the granular pattern is related to longitudinal vs transverse sectioning of affected dermal microfibril bundles. However, direct evidence for this possibility has yet to be presented. Confocal laser scanning microscopy and immunoelectron microscopy were performed to determine the anatomical distribution of fibrillar IgA deposits, using skin specimens from a patient with typical fibrillar IgA deposition.
Observations: Confocal laser scanning microscopy showed numerous fibrils stained with anti-IgA extending from the dermoepidermal junction to a depth of 50 to 110 microns in the dermis. They crossed each other at various angles to form a three-dimensional network. Immunoelectron microscopy demonstrated a diffuse dispersion of immune deposits on the surface of microfibrils of dermal microfibril bundles, with sporadic distribution of small aggregates, 0.1 to 0.3 micron in diameter.
Conclusions: To our knowledge, this is the first article to present evidence for the actual distribution of fibrillar IgA. Insofar as the present case is concerned, the distribution of fibrillar IgA is greatly at variance with that indicated in previous reports on granular IgA. However, studies on more cases should be conducted to determine whether this is a distinctive feature of the fibrillar type of IgA deposition.