Collagen specific amino acids in skin in localized scleroderma.

Hydroxyproline, hydroxylysine and proline were determined on skin from 18 patients with localized scleroderma (10 with localized morphoea plaque and 8 with generalized morphoea). Three skin biopsies (4mm punch) were obtained from each patient: One from the center of a sclerotic plaque, one from the perilesional area, and one (control) from unaffected skin of the same region. Clinically, the sclerosis was more pronounced (p less than 0.01) in localized morphoea plaque as compared to generalized morphoea. Patients with localized morphoea plaque had an increased concentration of hydroxylysine (p less than 0.01) and an increased ratio of hydroxylysine to hydroxyproline (p less than 0.01) in the plaques. Hydroxylysine concentration was not changed in patients with generalized morphoea. In the entire material, increased hydroxylysine concentration were related to shorter age of the plaques (p less than 0.05) and to advanced degree of sclerosis (p less than 0.05). The hydroxylysine and hydroxyproline content per mm2 skin surface, and the weight of the dried defatted biopsy cores were increased in sclerotic plaques (p less than 0.01) in localized as well as generalized morphoea. There were no changes in the hydroxyproline and proline concentrations in any of the groups. Specimens from perilesional area showed intermediate changes. The results were compared with selected cases of lichen sclerosis et atrophicus and atrophic skin diseases. The increase in hydroxylysine concentration and ratio to hydroxyproline indicate that patients with localized morphoea plaque contain an increased proportion of newly synthesized collagen in the fibrotic plaque.