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PATHOLOGY

In general, light microscopy has no role in the diagnosis of inherited EB, since it may be difficult to distinguish between even lower intraepidermal and subepidermal blister formation, let alone between intralamina lucida (i.e. JEB) and sublamina densa (i.e. dystrophic EB) types, without more sophisticated staining techniques being employed[35]. The only two diagnostic tests that are routinely employed are transmission electron microscopy (TEM) and a specialized form of immunohistochemistry (performed on non-formalin-fixed skin samples) termed immunofluorescence antigenic mapping. Discrepancies between these two techniques arise in only about 3% of all specimens, suggesting that either approach may serve as the gold standard for the diagnosis of inherited EB.

TEM distinguishes among the three major EB types by the identification of the ultrastructural level of cutaneous blister formation (see Figs 33.1 & 33.10). TEM can also be used to quantitatively and qualitatively assess …