Hashimoto’s thyroiditis and thyroid cancer: a case-control study of unselected patients with thyroid nodules submitted to cytological and hystological examination.

F. Boi;C. Satta;S. Casula;N. Arisci;C. Serafini;S. Scudu;F. Pani;M. L. Lai;S. Mariotti

2015-01-01

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Abstract

BACKGROUND: The association between thyroid autoimmunity or Hashimoto’s thyroiditis (HT) and thyroid cancer has been often suggested in many reviews but the relationship of this phenomenon is still debated. Aim of this study was to confirm this association in a retrospective series of patients who underwent fine needle aspiration cytology (FNAC). PATIENTS AND METHODS: The study group consisted in 152 patients with thyroid nodules associated to HT (HT+) diagnosed on the basis of ultrasound, serological (positive serum Tg-/TPO autoantibodies) and functional (increased serum TSH) criteria and 161 patients with thyroid nodules matched for age and gender and selected for the absence of any evidence of associated thyroid autoimmunity (HT-), representing the control group. Thyroid ultrasound and FNAC were performed in all cases. A subgroup of 111 patients underwent total thyroidectomy. RESULTS: HT+ patients had higher prevalence of suspicious/malignant cytology (Tir 4-5) (HT+ 44/152 = 28.9%; HT- 12/161 = 7.4%, p<0.0001) compared to HT- patients. A similar prevalence of indeterminate (Tir 3) cytology was found in HT+ (47/152 = 30.9%) and in HT- (45/161 = 28%). In the group submitted to thyroidectomy, malignant histology was found in 48/74 (64.9%) HT+ and in 16/37 (43.3%) HT- patients (p<0.05). The histotype distribution was 44 papillary (PTC), 2 follicular (FTC), 2 medullary (MTC) thyroid carcinomas in HT+ and 13 PTC, 2 FTC, 1 MTC in HT- patients, PTC being the only tumor significantly associated to HT. Taken together, a significantly higher number of histologically proven PTC was detected in HT+ (44/152 = 28.9%) vs HT- (13/161 = 8,1%, p<0.0001) patients originally submitted to FNA. Interestingly, the prevalence of multicentric PTC was significantly higher (14.4%) in HT+ than in HT- (5.6%) patients (p=0.0085). Finally, in the 70 surgical specimens with significantly diffuse or perinodular lymphocytic thyroid infiltration, a higher prevalence of PTC (46/70, 65.7%) was observed as compared to benign nodules (24/70, 34.3%; p<0.05). CONCLUSIONS: This study strongly confirms a significant association between HT and PTC based on both clinical and pathological results.