Ultrastructural observations on uninvolved skin in dermatitis herpetiformis

SUMMARY Clinically normal skin from patients being treated for dermatitis herpetiformis was examined with the electron microscope. Cytoplasmic processes from the basal epidermal cells penetrated the dermis through discontinuities in the basal lamina which otherwise was normal in structure and thickness. The fibrous network of the dermis consisting of collagen, small reticular fibrils, anchoring fibrils and elastin, appeared normal. In patients receiving only dapsone, membrane‐bound‘vacuoles’were found just below the basal lamina. They contained a fibrillar material of low electron density and were often associated with cell processes or complete cells, the classification of which was difficult. It is suggested that these vacuoles may be implicated in the reaction between reticulin and immunological complexes. In two specimens, early blister formation was also seen in the dermal papillae. The basal lamina remained applied to the stratum basale and was only absent where basal cell processes projected into the blister space which contained fibrin deposits. Vesiculated structures observed in the region of the blisters are interpreted as abnormal sensory nerve endings. This evidence supports the view that disruption of the basal lamina and blister formation in dermatitis herpetiformis are secondary to an earlier reaction.