Pseudoscleroderma as a paraneoplastic syndrome is a rare disease. We report here a patient with lung cancer (undifferentiated squamous cell carcinoma), who developed acrosclerosis. Using in situ hybridization, marked expression of alpha1(I)-collagen and connective tissue growth factor (CTGF) mRNA was found in fibroblasts scattered throughout the dermis. However, transforming growth factor (TGF)-beta1 expression was not detected. The pattern of CTGF gene expression and collagen synthesis was similar to that in systemic scleroderma. The absence of TGF-beta1 mRNA could indicate that tumour-derived factors induce the expression of CTGF.