Histopathologic and ultrastructural findings in certain genodermatoses

GENITOURINARY COMPLICATIONS OF INHERITED EPIDERMOLYSIS BULLOSA: EXPERIENCE OF THE NATIONAL EPIDERMYLOSIS BULLOSA REGISTRY AND REVIEW OF THE LITERATURE

PURPOSE

We determined the frequency with which 6 genitourinary tract complications (urethral meatal stenosis, urinary retention, bladder hypertrophy, hydronephrosis secondary to ureteral strictures, pyelonephritis and cystitis) occur in inherited epidermolysis bullosa (EB) in the American EB population.

MATERIALS AND METHODS

Up to 16 years of longitudinal followup was done in 3,280 consecutively enrolled patients in the National EB Registry, a National Institutes of Health funded epidemiological study covering the entire continental United States. Data were stratified by major EB type and subtype. Frequencies of occurrence were determined for each of 6 genitourinary tract variables and stratified into 10 mutually exclusive, major EB subtypes.

RESULTS

Urinary tract complications occurred in a minority of patients across all major EB subtypes with the highest frequency seen in Herlitz junctional EB (JEB-H). Urethral meatus stenosis was the most common complication, occurring in 11.6% and 8.0% of patients with JEB-H and Hallopeau-Siemens recessive dystrophic EB (RDEB), respectively. Urinary retention, hydronephrosis and bladder hypertrophy occurred in 9.3%, 7.0% and 4.6% of JEB-H cases, respectively. In contrast, pyelonephritis and cystitis were most often seen in the setting of generalized EB simplex (Koebner variant) and inversa RDEB.

CONCLUSIONS

The urinary tract may be involved in any subtype of inherited EB, although these complications usually arise in patients with the most severe subtypes of junctional and recessive dystrophic disease. Chronic surveillance for the presence of genitourinary tract disease activity is warranted, especially in patients with JEB and RDEB, given the potential for longterm kidney injury if untreated.

A comparative study of immunohistochemistry and electron microscopy used in the diagnosis of epidermolysis bullosa

Electron microscopic examination still is the gold standard for classifying epidermolysis bullosa, although it is relatively expensive, time consuming, and not readily available. Immunoreagents have been developed recently to map antigens in the basement membrane on routinely processed specimens. The current study was performed to examine the diagnostic usefulness of immunohistochemistry, as compared with electron microscopic examination, for analyzing routine formalin-fixed paraffin-embedded sections of epidermolysis bullosa. This study investigated 39 consecutively diagnosed cases of epidermolysis bullosa in which both electron microscopic examination and immunohistochemistry were used. In each case, three monoclonal antibodies were used to stain for laminin 1, collagen IV, and keratin. The immunohistochemical patterns were defined as follows: epidermolysis bullosa simplex (laminin, collagen IV, or both at the dermal floor of the blister and keratin at both the dermal floor and the epidermal roof), junctional epidermolysis bullosa (laminin, collagen IV, or both at the dermal floor of the blister and keratin only at the epidermal roof), and dystrophic epidermolysis bullosa (collagen IV, laminin, or both, and keratin all at the epidermal roof). Altogether, electron microscopic examination subclassified epidermolysis bullosa into its three major forms in 37 of the 39 cases (95%), and immunohistochemistry in 33 of the 39 cases (85%). All of the classifiable cases were concordant. Specifically, immunohistochemistry was diagnostic in 10 of 14 (71%) epidermolysis bullosa simplex cases, 14 of 14 (100%) junctional epidermolysis bullosa cases, and 9 of 11 (82%) dystrophic epidermolysis bullosa cases. The most frequent cause for inconclusive immunohistochemical results was failure in staining of the basement membrane with the antibodies to both laminin and collagen IV. In conclusion, the use of immunohistochemistry on routinely processed specimens may be useful for subclassifying epidermolysis bullosa into its major forms in the majority of the cases, although it still cannot fully replace electron microscopic examination or immunofluorescence mapping in the diagnosis of epidermolysis bullosa.

Epidermolysis bullosa: hereditary skin fragility diseases as paradigms in cell biology

Recent research into the molecular basis of epidermolysis bullosa has provided a unique insight into a variety of mechanisms in normal cell biology, such as cell-matrix interactions, and has uncovered an excellent model for studies on keratin intermediate filaments. The simplex forms of epidermolysis bullosa are caused by mutations in the genes for the basal epidermal keratins, K5 and K14. Most mutations affect highly conserved parts of the molecules, illustrating their importance in normal keratin filament assembly and integrity. Mutations in corresponding regions of the differentiation-associated keratins, K1 and K10 can also occur in epidermolytic ichthyosis. Both recessive and dominant forms of dystrophic epidermolysis bullosa result from mutations in an anchoring fibril collagen gene, COL7A1. Junctional epidermolysis bullosa is caused by mutations in the genes encoding different chains of the novel laminin isoform, nicein/kalinin, also known as laminin 5, which is associated with the anchoring filament-hemidesmosome complex of the basement membrane zone. These recent findings strengthen the evidence for the role of nicein/kalinin and type VII collagen in adherence and stabilization of the dermo-epidermal junction.

HLA and epidermolysis bullosa: evidence for independent assortment of Weber-Cockayne subtype of epidermolysis bullosa and HLA complex

The purpose of this study was to examine the genetic linkage (but not the association) between HLA complex and Weber-Cockayne Subtype of epidermolysis bullosa (EBS-WC). We HLA typed 44 members of three multi-generation families in which 24 members have the clinical evidence of EBS-WC. The patterns of inheritance of various HLA haplotypes and the disease were mathematically analyzed to estimate frequency of recombination (i.e. genetic distance) between HLA complex and the disease by calculating Lod Scores for each family separately as well as all for three families combined. Our results show that only one family had a positive Lod Score. The Lod Scores for the remaining two families as well as the combined Lod Score for all three families were negative. These data suggest that odds are against the genetic linkage between HLA complex and Weber-Cockayne Subtype of epidermolysis bullosa and in favor of independent assortment of the disease and HLA complex.

Immunoelectron microscopy and immunofluorescence antigenic mapping: diagnostic applications

In selected situations, direct and indirect IEM may provide important diagnostic information for the clinician, as pertains to the diagnosis and therefore prognosis in a given patient. As discussed, however, all of the more conventional approaches should be pursued before consideration is given to the performance of IEM, knowing its relative cost and technical difficulty. In contrast, we consider immunofluorescence antigenic mapping to be the diagnostic method of choice for the determination of the type of inherited EB present in affected individuals. When additional ultrastructural or morphometric data is required, then TEM can be performed as an adjunct study once it is determined by mapping technique that additional useful information may be derived.

Revised clinical and laboratory criteria for subtypes of inherited epidermolysis bullosa. A consensus report by the Subcommittee on Diagnosis and Classification of the National Epidermolysis Bullosa Registry

Inherited epidermolysis bullosa encompasses a number of diseases, with the common finding of blister formation after minor mechanical trauma to the skin. In some forms significant, if not eventually fatal, extracutaneous disease activity may occur. In recent years application of newer technologies has contributed substantially to an overall understanding of this collection of inherited diseases. Concurrently, many new phenotypes have been recognized, in part the result of ongoing prospective patient registries in the United States and abroad. Unfortunately, this has resulted in a massive literature that may appear to be confounded by seemingly excessive or arbitrary subdivision of epidermolysis bullosa variants. With these concerns in mind a subcommittee was established by the National Epidermolysis Bullosa Registry to summarize the current literature and to make recommendations as to the best clinical and laboratory criteria for the practical diagnosis and subclassification of patients with inherited epidermolysis bullosa.

Applicability of 19-DEJ-1 monoclonal antibody for the prenatal diagnosis or exclusion of junctional epidermolysis bullosa

Recently a monoclonal antibody (19-DEJ-1) was produced with binding specificity for the mid-lamina lucida of the skin dermo-epidermal junction, in very close association with overlying hemidesmosomes. Since skin cleavage occurs within the lamina lucida in the inherited blistering disorder, junctional epidermolysis bullosa (EB), and is associated with aberrations in the morphology and/or number of hemidesmosomes in such tissue, we have sought to determine whether this monoclonal antibody could be used for prenatal diagnosis. Fetoscopy-directed skin biopsies were obtained from two fetuses at risk for junctional EB and post-mortem samples from two other fetuses with the Herlitz type of junctional EB, the latter after prenatal diagnosis by electron microscopy and termination of each pregnancy. Specimens were examined in part by light and electron microscopy for evidence of skin cleavage or other alterations in morphology, and in part by indirect immunofluorescence for altered basement membrane antigenicity. Three of four fetuses were shown to have intra-lamina lucida blister formation indicative of, and hemidesmosome hypoplasia proving, junctional EB. Each was also shown to lack expression of GB3 and 19-DEJ-1 antigens, consistent with findings noted postnatally in junctional EB; diagnosis was confirmed in each at the time of therapeutic abortion. A fourth fetus had no abnormalities detected; lack of disease involvement was confirmed at the time of delivery, and subsequently over 8 months of careful serial evaluation. We conclude that 19-DEJ-1 monoclonal antibody is an accurate and sensitive immunohistochemical probe for junctional EB, and may be employed in the prenatal diagnostic evaluation of fetuses at risk for this disorder.

Epidermolysis bullosa simplex: identification of a kindred with autosomal recessive transmission of the Weber-Cockayne variety

With few exceptions, epidermolysis bullosa simplex (EBS) is transmitted as an autosomal dominant trait. All cases of autosomal recessive EBS reported to date have been associated with significant extracutaneous disease (including anemia, marked growth retardation, dentition abnormalities, and/or concurrent neuromuscular disease), early infant mortality, or often, rather extensive cutaneous involvement. In some, the cutaneous morphology has even suggested junctional or dystrophic disease. We cared for a kindred in which four individuals were affected with an autosomal recessive form of EBS with cutaneous findings most often suggestive of Weber-Cockayne disease. Except for scattered oral erosions in one patient, there was no evidence of associated extracutaneous disease. These findings demonstrate the increasing complexity of even the simplex forms of inherited epidermolysis bullosa. This obviously has implications for genetic counseling.