An important differential diagnosis of NSF is systemic sclerosis (SSc). While both NSF and SSc at their late stage frequently result in widespread skin sclerosis, other characteristic features of SSc such as Raynaud phenomenon, sclerodactyly, digital pitting scars, and facial involvement (eg, masklike skin, telangiectasias, shrunken nose, radial furrowing around the mouth, and microcheilia) are absent in NSF. Besides their clinical similarities, both conditions are characterized by excessive collagen deposition and expression of transforming growth factor β (TGF-β). Some years ago, high proportions of expanded clonal T-cell populations were detected in the peripheral blood of patients with SSc, suggesting a pathogenetic role in the disease.5,6 Interestingly, one study showed that patients with SSc with circulating clonal T cells had a better chance of response to treatment with extracorporeal photopheresis,5 which has recently been reported to have mild beneficial effects in NSF as well.7 The purpose of this pilot study was to search for clonally expanded T-cell populations in the peripheral blood of patients with NSF. Moreover, we thought to determine whether the presence of clonal T cells is associated with a response to photopheresis.