Abstract
A man in his 20s had a ten-year history of swelling and hardening on the lateral sides of the PIP joint in the 2nd to 5th fingers on both hands. He had a habit of frequently folding his hands, and he used a personal computer for 8 hours a day for several years. No abnormal joint movement or abnormal findings on X-ray examination were observed. MRI revealed swelling and ligament thickening around the same area. Pathology demonstrated mild hyperkeratosis, -epidermal hyperplasia and increased collagen fibers throughout the dermis. Elastic fibers were segmented and decreased. Electron microscopy confirmed marginal irregularities and size disparities in collagen fibers, which were characteristic in our case. Therefore, we diagnosed this case as pachydermodactyly. Oral tranilast and steroid local injection were both ineffective. Our case was characterized by electron microscopic observation of thick collagenous fibers. We speculate that the persistence of extrinsic stimulus increased the collagen fiber diameter and density of the ligament. Similar changes were seen in collagen fibers of the dermis.Skin Research, 17: 163-167, 2018
