Fibrosis is the development of thick fibrous tissues in any organ or tissue. If fibrosis occur in skin then it is dermal fibrosis. This causes thickening and tightening of skin. There are many conditions which can cause dermal fibrosis like sclreroderma, Amyloidosis, Polymyositis, Peyronie's disease, Carcinoid tumour, Morphoea, and Mixed connective tissue disease etc. If you are suspecting dermal fibrosis then visit a dermatologist.