May be caused by immunologic disorders, inflammatory processes, metabolic disorders, depositional disorders, and exposure to toxins.
Among immunologic or inflammatory disorders are: eosinophilic fasciitis, graft-vs.-host disease, lichen sclerosus et atrophicus, SLE, dermatomyositis size and scleroderma.
Associated metabolic conditions include porphyria cutanea tarda, myxedema, and phenylketonuria.
Deposition processes include amyloidosis sclerederma, nephrogenic systemic fibrosis and scleromyxedema.
Exposure to L. tryptophan and toxic oils may induce skin induration.