Epidermolysis bullosa simplex (Dowling-Meara). A clinicopathological review

The clinicopathological features of 22 cases of the Dowling-Meara form of epidermolysis bullosa simplex (DM-EBS) (11 males, 11 females; aged 5 days-46 years) were reviewed using data collected over a 10-year period. All cases presented clinically within the first 5 days of life. Early blisters were often large (up to 5 cm in diameter), and were mostly acral and particularly periungual. Some cases presented with more widespread erosive skin changes, and two neonates with extensive skin involvement died as a result of overwhelming sepsis. After the neonatal period a different pattern of blistering occurred with more proximal haemorrhagic, herpetiform clusters of blisters. Central healing with recurrent blistering at the margins of these areas was frequently noted. Other physical signs included varying degrees of intra-oral blistering, nail shedding, nail dystrophy, minor scarring, palmo-plantar keratoderma, a lack of seasonal variation and improvement during later childhood. The underlying pathological mechanism in DM-EBS is basal cell cytolysis, or rarely acantholysis, in association with tonofilament (TF) clumping. TF clumping was found in lesional, perilesional and some non-lesional skin, suggesting that the tonofilament abnormality may be of primary aetiological significance in DM-EBS. TF clumping may be due to specific keratin abnormalities because the altered TF were found in a distribution similar to the known distribution of the basal cell keratins, K5 and K14. The level of blistering was invariably very low within the epidermal basal layer and often less than 0.5 microns above the basement membrane. We conclude that DM-EBS is a distinct, and probably under-recognized genodermatosis which tends to have a good prognosis. However, the disease can occasionally be severe, especially during the neonatal period, when it may be confused with junctional or severe recessive dystrophic EB. Electron microscopy is the best means for demonstrating the characteristics cytoskeletal disorder and confirming the diagnosis.