Antigen diffusion and uptake: a caveat in immunohistochemical interpretation.

Abstract

Thyroglobulin was demonstrated by monoclonal immunohistochemistry in the cytoplasm of renal cell carcinoma cells metastatic to the thyroid gland. This was attributed to release of thyroglobulin from injured native thyroid with diffusion and uptake by tumor cells. Previously reported cases of this process in tumors in thyroid, skeletal muscle, and lymphoid tissue are reviewed. Interpretation of the significance of demonstrated antigens in tumor cells, especially those that are constituents of invaded native tissues and only focally present, should be interpreted with caution and in conjunction with other histologic evidence.