Excessive collagen formation in fibrolamellar carcinoma of the liver: a morphological and biochemical study.

We have studied the excessive deposition of extracellular matrix in a patient with fibrolamellar carcinoma of the liver. The collagen matrix was predominantly composed of collagens I, III, and V. Since specific mRNAs for collagens I and III were detected by in situ hybridization, we also provide evidence that the fibroblastoid stromal cells were the major source of this collagen. Occasionally, also tumor cells could be shown to express collagen III-mRNA. Furthermore, some tumor cells showed positive signals for TGF-beta 1, while isolated stromal cells expressed interleukin-6. This cytokine expression may probably be related to the altered control of collagen gene expression.