Systemic Sclerosis

An Update

Uwe-Frithjof Haustein, MD, PhD


Lab Med. 2011;42(9):562-572. 

In This Article

Environmental Factors

Environmental factors, including chemical compounds such as solvents or drugs (bleomycin is best known), can induce SSc-like diseases upon exposure[89,57] that can be distinguished from SSc by the following features:[89]

  • Type of skin manifestation, in particular acrosclerosis, circumscribed and generalized morphea, fibrotic nodules, joint contractures.

  • Visceral involvement due to toxic damage of the liver, kidney, nervous system, and muscles, as well as angiosarcoma of the liver.

  • Laboratory findings of partial thrombocytopenia, and absence of Auto-ab.

  • Cessation or reversibility of the disease process after early discontinuation of the exposure.

In contrast to these chemical substances, silica is able to induce a form of SSc-like disease indistinguishable from idiopathic SSc[90,91] as shown by clinical and laboratory data and similar pathophysiology. Therefore, silica should be accepted as an inducer of SSc. This is in agreement with Rodnan and colleagues[92] and Rustin and colleagues.[90] Our experimental data concerning the exposure of various cell-(co)cultures such as macrophages/monocytes, EC, and FBs to silica support the hypothesis that silica-mediated cell activation can play a role in the pathogenesis of SSc.[57] However, the long exposure times needed for the onset of silica-induced SSc and the fact that not all exposed persons develop silicosis and SSc suggest silica alone does not cause SSc. The development of SSc in a silica-exposed individual depends not only on the length and concentration of exposure but also on the individual genetic background of the host. Several cases have been published in which SSc, after long-term exposure with silica, was acknowledged as an occupational disease, mostly by an individual decision. In addition, exacerbation of SSc, or even the new onset of diffuse SSc cases, has been observed after X-ray treatment.[93]


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