POORLY DIFFERENTIATED OXYPHILIC (HURTHLE CELL) CARCINOMAS OF THE THYROID

A series of 60 cases of oxyphilic (Hurthle cell) carcinomas (HCC) of t he thyroid were reviewed to determine whether it is possible to correl ate morphologic and clinical features as a means of assessing prognosi s. Twenty cases showing predominant solid or trabecular patterns (as d escribed in poorly differentiated carcinomas with a follicular pattern ) were selected and the clinicopathological features were investigated . Based on cell size, two groups of solid or trabecular HCCs were iden tified: The first group (17 cases) was made up of typical large granul ar oxyphilic cells, and the second (three cases) had small oxyphilic c ells. All tumors were reactive for thyroglobulin and for a mitochondri al antigen, selectively marking oxyphilic, mitochondrial-rich cells. N uclear pleomorphism in individual cells was a common feature, but foci of anaplastic carcinoma were never found. Four cases overexpressed p5 3 protein and 10 expressed bcl-2 gene product. At follow-up, among the high-stage (pT3-pT4) tumors, seven patients had recurrences or metast ases, six of whom were alive with disease or died of disease. In the c ontrol group of HCC with predominant follicular patterns, only one of 40 cases had a fatal outcome. The difference was statistically signifi cant. Small-cell patterns and a p53 protein-positive/bcl-2 gene produc t negative phenotype were features of clinically aggressive HCC cases. We suggest that within the spectrum of oxyphilic (Hurthle cell) tumor s, poorly differentiated HCC showing solid or trabecular patterns are a distinct group, based on both morphological and clinical features.