Pathogenesis of telangiectasia in scleroderma
Scleroderma (progressive systemic sclerosis) is a systemic autoimmune disorder characterised by skin sclerosis, calcinosis and changes in microvasculature. The etiology of the disease is unknown but both genetic and environmental factors have been implicated. Telangiectasia (macroscopically visible dilated skin vessels) occurring primarily on the hands and face, are a prominent feature in scleroderma and are present in the majority of patients. Similarly, telangiectasia are found in patients with hereditary hemorrhagic telangiectasia (HHT), a mutational disorder of the germline genes endoglin and ALK-1, members of the TGFbeta receptor family, expressed on endothelial cells. Our study investigated the number, distribution and microscopic characteristics of telangiectasia in both limited (n = 29) and diffuse scleroderma (n = 9) and compared findings with 3 patients with HHT. In limited scleroderma, the mean number of telangiectasia (hand and face) was 36 (0-150) compared with 23 (0-135) in diffuse scieroderma. A significant correlation was observed between the number of telangiectasia on the face and on the hands (p = 0.014). The total number of telangiectasia correlated significantly with the disease duration (p = 0.009). The spatial distribution of the telangiectasia appeared to be random on both hands and foreface in contrast with the distribution of subcutaneous calcification of the hands which occurred predominantly on the distal and flexor surfaces of the first, second and fifth digits. Nailfold microscopic capillaroscopy was performed on 12 patients. No significant correlation was observed between capillary diameter or density and with total number of telangiectasia observed macroscopically. The distribution and microscopic appearance of telangiectasia in scleroderma appeared very similar to those observed in HHT. In view of these similarities we therefore conclude that telangiectactic development in scleroderma may be associated with disorders of the TGFb receptor family proteins found on the microvasculature.