The Role of Collagen IV and Cytokeratin 5/6 Immunohistochemistry in Identifying Subtypes of Hereditary Epidermolysis Bullosa

Hereditary epidermolysis bullosa (EB) constitute a genodermatosis group with variable clinical severity. Biopsies diagnosed as EB in the last 4 years were retrieved from the database of the king Khalid University Hospital and military hospital lab at Saudi Arabia. The current study was performed to examine the diagnostic usefulness of immunohistochemistry, as compared with electron microscopic examination, for subclassification of HEB. Fourteen cases were studied. Collagen IV immunostain was located above the blister in all dystrophic EB cases, and below the blister in all cases of epidermolytic and junctional EB. Cytokeratin 5/6 was visible above the blister in all cases of dystrophic and junctional types EB. In 2 out of 4 cases of epidermolytic EB, cytokeratin 5/6 was seen only above the cleft, whereas 1 case revealed positivity above and below the blister. One epidermolytic EB case showed scattered fragments of keratinocytes inside the blister.

A comparative study between transmission electron microscopy and immunofluorescence mapping in the diagnosis of epidermolysis bullosa

The classification of epidermolysis bullosa (EB) into 3 main subtypes has been based on transmission electron microscopy (TEM) that is able to directly visualize and quantify specific ultrastructural features. Immunofluorescence antigenic mapping (IFM) is a technique that determines the precise level of skin cleavage by determining binding sites for a series of antibodies. To date, no study has compared the accuracy of these two techniques in diagnosing the major types of EB. A prospective cohort of 33 patients thought to have EB on clinical grounds had TEM, IFM, and genetic testing performed. The sensitivities and specificities of TEM and IFM were calculated compared with the genetic results. Of 33 cases, 30 had a positive EB diagnosis. TEM subclassified EB into its three major forms in 24/30 cases (80%) and IFM in 29/30 cases (97%). Overall, TEM sensitivities and specificities when compared with genetic results were 71% and 81%, respectively. IFM sensitivities and specificities when compared with genetic results were 97% and 100%, respectively. If a patient tested positive for EB by IFM, the likelihood ratio of having a particular type of EB was consistently greater than 20 against the reference standard (compared with a likelihood ratio less than 10 for TEM). Our results indicate that the diagnosis of EB is improved (sometimes substantially) by the use of IFM compared with TEM.

Autoantibodies in anti-p200 pemphigoid stain skin lacking laminin 5 and type VII collagen

We report the case of a patient with a widespread bullous skin disease and linear deposits of IgG and C3 at the dermal-epidermal junction using direct immunofluorescence microscopy. Indirect immunofluorescence analysis demonstrated circulating IgG autoantibodies that stained, like autoantibodies to laminin 5 and type VII collagen, the dermal side of 1 mol L-1 NaCl-split human skin. By immunoblotting dermal extracts, the patient's serum, like serum samples from two control patients, reacted with a 200-kDa protein. Using immunoelectron microscopy, the serum labelled a component of the lower lamina lucida, but not the lamina densa/sublamina densa region, distinguishing this from the type VII collagen localization pattern. By immunofluorescence microscopy on skin sections from patients lacking either laminin 5 (Herlitz's epidermolysis bullosa) or type VII collagen (recessive dystrophic epidermolysis bullosa of Hallopeau-Siemens), the patient's serum retained reactivity with these test substrates. The patient's disease responded rapidly to the use of topical corticosteroids and lesions healed without scarring or milia formation. Our results provide strong evidence for the hypothesis that the 200 kDa autoantigen is different from laminin 5 and type VII collagen. For this new disease, we propose the designation 'anti-p200 pemphigoid'.