P53 IN A THYROID FOLLICULAR CARCINOMA WITH FOCI OF POORLY DIFFERENTIATED AND ANAPLASTIC CARCINOMA

The clinical and pathologic features of a rare case of follicular carc inoma with small foci of poorly differentiated and anaplastic carcinom a are presented. Eight years after the removal of the primary neoplasm , the patient developed pulmonary and brain metastases that were predo minantly composed of the poorly differentiated and anaplastic componen ts. A comparative immunohistochemical and molecular analysis of p53 st atus in the follicular, poorly differentiated and anaplastic component s of the tumor was performed. p53 immunostaining was restricted to the poorly differentiated and anaplastic areas. Single strand conformatio n polymorphism analysis (SSCP-PCR) from DNA obtained by microdissectio n demonstrated the presence of a mutation (TAT --> TGT; Tyr --> Cys) i n codon 220, exon six of the p53 gene in the anaplastic component, tha t was absent in the well-differentiated follicular areas. The results of that study in this rare tumor support that p53 has a tumor progress ion role in thyroid tumorigenesis.