It has also been observed that PSMA expression depends on histology; moderate to high grade expression of PSMA has been documented in classic papillary, follicular and papillary with follicular variant histologies, as well as in radioiodine – refractory subtypes (RAIR); and weak to null expression in anaplastic thyroid carcinoma (21). This evidence concerns the gene FOLH1 and thyroid gland undifferentiated (anaplastic) carcinoma.