Background. The tall cell variant (TCV) is a clinically aggressive subtype of papillary thyroid cancer. The aim of this study was to discover the prevalence of mutant forms of p53 protein in this subtype and relate it to clinical outcome. Methods. Eighteen patients with TCV and a control group with common papillary cancers, matched for age and gender, were studied. The p53 mutations were identified by means of immunohistochemical staining. Data reviewed were overall survival, recurrence, TNM stage, and p53 positivity. Results. p53 mutations occurred in 11 (61%) patients with TCV compared with two (11%) in control group (p = 0.05). In the TCV group two patients died of the disease (11%) and eight (44%) had local recurrences or distant metastases compared with none in the control group. All deaths and 70% of the recurrences occurred in patients with stage III or IV disease. p53 positivity did not correlate with any reduction in survival (7% compared with 9%) but with increased rate of local (23% compared with 4%) and distant (23% compared with 13%) recurrences. Conclusions. TCV was associated with a significantly higher rate of p53 positivity than common papillary carcinoma. The stage of the disease seemed to be a better prognostic indicator than p53 positivity for overall survival.
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