Retention of intracellular fibronectin expression in primary and metastatic thyroid carcinoma: an immunohistochemical study

We previously showed that thyroid carcinoma distinctively expresses intrace llular fibronectin (FN) compared to other carcinomas. To determine the pers istency of such FN accumulation in metastasis, we immunohistochemically exa mined the accumulation of intracellular FN in 92 cases of different carcino mas originating from the thyroid gland, lung and kidney, 44 of which showed metastasis to other organs. In all of the cases, normal epithelial cells a djacent to carcinomas did not show intracellular FN. Almost all of the case s (31/32) of thyroid carcinoma with/without metastasis to the lung and/or k idney showed intracellular FN in both the primary and metastatic lesions. F ew cases (2/38) of lung carcinoma and none of the 22 cases of kidney carcin oma showed intracellular FN in the primary and metastatic lesions. In concl usion, the intracellular accumulation of FN acquired after carcinogenic tra nsformation is not a common phenomenon in carcinomas, but rather is distinc tive for thyroid carcinoma, even when it metastasizes to other organs. The immunohistochemical detection of intracellular FN may be useful for diagnos ing thyroid carcinoma, even in metastatic lesions. (C) 1998 Elsevier Scienc e Ireland Ltd. All rights reserved.