Skin biopsies will show marked thickening and uniformity of the collagen bundles of the skin. Sweat glands are seen entrapped in the sclerosing process. Signs of chronic inflammation can be seen through the deep layers of the skin. Excess fibrous tissue replaces hair follicles. In morphea profunda, inflammation extends into the subcutaneous tissues.
Muscle biopsies show abnormalities in the muscle cells.
Muscle fibers show evidence of inflammation and changes similar to juvenile rheumatoid arthritis. Microscopic analysis of the nail folds of the fingers is a non-invasive way to diagnose several connective tissue diseases, including scleroderma, and to differentiate between systemic and localized forms. Morphea and linear scleroderma do not show the typical nail fold pattern of the systemic form and this is true for all cells, not just those in a plaque. Another non-invasive test to determine the activity level of the disease in patients with linear scleroderma is thermography. An infrared camera detects changes in skin temperature.